A3000 Service Manual

3000 Service Manual

3000 Service Manual

Copyright © Acorn Computers Limited 1989

Neither the whole nor any part of the information contained in, nor the product described in this Guide may be adapted or reproduced in any material form except with the prior written approval of Acorn Computers Limited.

The products described in this manual are subject to continuous development and improvement. All information of a technical nature and particulars of the products and their use (including the information and particulars in this

Manual) are given by Acorn Computers Limited in good faith. However, Acorn Computers Limited cannot accept any liability for any loss or damage arising from the use of any information or particulars in this manual, or any incorrect use of the products. All maintenance and service on the products must be carried out by Acorn Computers' authorised dealers or Approved Service Centres. Acorn Computers Limited can accept no liability whatsoever for any loss or damage caused by service, maintenance or repair by unauthorised personnel.

All correspondence should be addressed to:

Customer Service

Acorn Computers Limited

Fulbourn Road

Cherry Hinton

Cambridge CB1 4JN

Information can also be obtained from the Acorn Support Information Database (SID). This is an on-line viewdata system available to registered SID users. Initially, access SID on Cambridge (0223) 243642: this will allow you to inspect the system and use a response frame for registration.

ACORN and ECONET are trademarks of Acorn Computers Limited.

IBM is a trademark of International Business Machines Corporation.

Within this publication, the term 'BBC' is used as an abbreviation for 'British Broadcasting Corporation'.

2

Published September 1989

Published by Acorn Computers Technical Publications Department

Part number 0480,050 Issue 1

3000

Contents

System description

Introduction

General

The I/O system

The sound system

The keyboard and mouse

Floppy disc drive

Power supply

Links

Plugs

Sockets

Changes between Issue A and Issue 1 PCBs

A3000 expansion

Internal expansion

External expansion

Disassembly and reassembly

Fault diagnosis

Introduction

Checking a 'dead' computer

Functional tests

Main computer tests

Upgrade tests

Main PCB fault diagnosis & repair

Introduction

System failure

Video faults

Peripheral faults

Test ROMs

Parts lists

Appendix A: Serial port loopback plug

Appendix B: Earth continuity testing

Drawings

A3000 final assembly diagram

User Port / MIDI circuit diagram

Internal upgrade diagram

External podule fixing diagram

Main PCB circuit diagram

Main PCB top assembly diagram

Main PCB bottom assembly diagram

)

)

) bound separately

25

25

29

31

5

13

14

19

19

20

21

21

23

5

5

6

51

55

57

45

45

46

46

47

48

33

33

34

36

38

42

Service Manual

3

4

3000 Service Manual

3000

System description

Introduction

The A3000 computer is built around the ARM chip set, comprising the Acorn Risc Machine (ARM) itself, the

Memory Controller (MEMC), Video Controller (VIDC)

Service Manual

and Input Output Controller (IOC).

A block diagram of the A3000 is shown below:

General

The ARM IC is a pipelined, 32-bit reduced instruction set microprocessor which accepts instructions and manipulates data via a high speed 32-bit data bus and 26-bit address bus, giving a 64 Mbyte uniform address space. The ARM supports virtual memory systems using a simple but powerful instruction set with good high-level language compiler support.

MEMC acts as the interface between the ARM, the

Video and I/0 Controllers, Read-Only Memory (ROM) and Dynamic memory devices (DRAM), providing all the critical system timing signals including processor clocks.

1 or 2 Mbyte of DRAM is connected to MEMC which provides all signals and refresh operations. A Logical to Physical Translator maps the Physical Memory into a 32 Mbyte Logical address space (with three levels of protection) allowing Virtual Memory and Multi-

Tasking operations to be implemented. Fast page mode DRAM

System description

accesses are used to maximise memory bandwidth.

VIDC requests data from the RAM when required and buffers it in one of three FIFOs before using it. Data is requested in blocks of four 32-bit words, allowing efficient use of paged-mode DRAM without locking the system data bus for long periods.

MEMC supports Direct Memory Access (DMA) operations with a set of programmable DMA Address

Generators which provide a circular buffer for Video data, a linear buffer for Cursor data and a double buffer for Sound data.

The Input Output Controller (IOC) controls the I/O bus and expansion cards, and provides basic functions such as the keyboard interface, system timers, interrupt masks and control registers. It supports a number of different peripheral cycles, and all I/O accesses are memory mapped.

5

3000 Service Manual

VIDC takes video data from memory under DMA control, serialises it and passes it through a colour lookup palette, then converts it to analogue signals for driving the CRT guns. VIDC also controls all the display timing parameters and controls the position and pattern of the cursor sprite. In addition, it incorporates an exponential Digital to Analogue

Converter (DAC) and stereo image table for the generation of high quality sound from data in the

DRAM.

VIDC is a highly programmable device, offering a very wide choice of display formats. The colour look-up palette which drives the three on-chip DACs is 13 bits wide, offering a choice from 4096 colours or an external video source.

The cursor sprite is 32 pixels wide and any number of rasters high. Three simultaneous colours (again from a choice of 4096) are supported and any pixel can be defined as transparent, making possible cursors of many shapes. It can be positioned anywhere on the screen.

The sound system implemented on the device can support up to 8 channels, each with a separate stereo position.

The I/O system

The I/O system is controlled by the I/O Controller (IOC) and the Memory Controller (MEMC). The I/O Bus supports all the internal peripherals and the expansion cards. Details of the expansion bus can be found in the chapter entitled 'A3000 expansion'.

This section is intended to give the reader a general understanding of the A3000 I/O system and should not be used to program the I/O system directly. The implementation details are liable to change at any time and only the published software interfaces should be used to manipulate the I/O system. Future systems may have a different implementation of the I/O system, and in particular the addresses (and number) of expansion card locations may move. For this reason, and to ensure that any device may be plugged into any slot, all driver code for expansion cards must be relocatable. References to the direct expansion card addresses should never be used. It is up to the machine operating system, in conjunction with the expansion card ID, to determine the address at which an expansion card should be accessed. To this extent, some of the following sections are for background information only.

6 System description

3000 Service Manual

System architecture

The I/O system (which includes expansion card devices) consists of a 16-bit data bus (BD[0:15]) a buffered address bus (LA[2:21]) and various control and timing signals. The I/O data bus is independent of the main 32bit system data bus, being separated from it by bidirectional latches and buffers. In this way the I/0 data bus can run at much slower speeds than the main system bus to cater for slower peripheral devices. The latches between the two buses, and hence the I/O bus timing are controlled by IOC. IOC caters for 4 different cycle speeds (slow, medium, fast and synchronous).

A typical A3000 I/O system is shown in the diagram on the previous page. For clarity, the data and address buses are omitted from this diagram.

System memory map

The system memory map is defined by the MEMC, and is shown below. Note that all system components, including I/O devices, are memory mapped.

I/O space memory map

This IOC-controlled space has allocation for simple expansion cards and MEMC expansion cards.

Data bus mapping

The I/O data bus is 16 bits wide (8 bits wide for the internal expansion card interface). Bytewide accesses are used for 8-bit peripherals. The I/O data bus (BD[0:

15]) connects to the main system data bus (D[0:31]) via a set of bidirectional data latches.

System memory map

Read

ROM (high)

Write

Logical to Physical address translator

ROM (low)

Input/Output

Video

DMA address generators

Controller

Controllers

Physically mapped RAM

The mapping of the BD[0:15] bus onto the D[0:31] bus is as follows:

During a WRITE (ie ARM to peripheral) D[16:31] is mapped to BD[0:15].

During a READ (ie peripheral to ARM) BD[0:15] is mapped to D[0:15].

Byte accesses

To access bytewide expansion cards, byte instructions are used. A byte store instruction will place the written byte on all four bytes of the word, and will therefore correctly place the desired value on the lowest byte of the I/O bus. A byte or word load may be used to read a bytewide expansion card into the lowest byte of an ARM register.

Half-word accesses

To access a 16-bit wide expansion card, half-word instructions are used. When storing, the half-word is placed on the upper 16 bits, D[16:31]. To maintain upwards compatibility with future machines, half-word stores replicate the written data on the lower half-word,

D[0:15]. When reading, the upper 16 bits are undefined.

Expansion card identification

It is important that the system is able to identify what expansion cards (if any) are present, and where they are. This is done by reading the Podule (expansion card) Identification (PI) byte, or bytes, from the Podule

Identification Field.

Hex address

3FFFFFF

3800000

3600000

3400000

3000000

2000000

Logically mapped RAM

0000000

System description 7

3000 Service Manual

I/O address memory mapping

All I/O accesses are memory mapped. IOC is connected as detailed in this table:

ARM

IOC

CS

T[1]

T[0]

B(2]

B[1]

B[0]

LA[21]

LA[20]

LA[19]

LA[18]

LA[17]

LA[16]

Internal register memory map

Address

3200000H

3200004H

3200008H

320000CH

3200010H

3200014H

3200018H

320001CH

3200020H

3200024H

3200028H

320002CH

3200030H

3200034H

3200038H

320003CH

3200040H

3200044H

3200048H

320004CH

3200050H

3200054H

3200058H

320005CH

3200060H

3200064H

3200068H

320006CH

3200070H

3200074H

3200078H

320007CH

Read Write

Control Control

Serial Rx Data Serial Tx Data

-

-

-

-

IRQ status A -

IRQ request A IRQ clear

-

IRQ mask A

IRQ status B -

IRQ request B -

-

IRQ mask A

-

IRQ mask B

FIQ status

FIQ request -

-

-

IRQ mask B

-

FIQ mask

-

FIQ mask

T0 count Low T0 latch Low

-

T0 count High T0 latch High

T0 go command

T0 latch command

T1 count Low T1 latch Low

-

T1 count High T1 latch High

T1 go command

T1 latch command

T2 count Low T2 latch Low

T2 count High T2 latch High

-

T2 go command

T2 latch command

T3 count Low T3 latch Low

-

-

T3 count High 13 latch High

T3 go command

T3 latch command

8

Peripheral address

Cycle Base

Type Bk Address IC Use

Fast 1 &3310000 1772

Sync 2 &33A0000 6854

Sync 3 &3380000 6551

Floppy disc controller

Econet controller*

Serial line controller*

Med. 5 &32D0000 HD63463 Hard disc**

Med. 5 &32D0020 HD63463 Hard disc**

Med. 5 &32D0008 HD63463 Hard disc**

Med. 5 &32D0028 HD63463 Hard disc**

Fast 5 &3350010 HC374

Fast 5 &3350018 HC574

Fast 5 &3350040 HC574

6 -

Slow 4 &3244000 Podule

Med. 4 &32C4000 Podule

Fast 4 &3344000 Podule

Sync 4 &33C4000 Podule

Slow 4 &3240000 Podule

Med. 4 &32C0000 Podule

Fast 4 &3340000 Podule

Sync &33C0000 Podule

Slow 7 &3270000 Podule

Printer Data

Latch B

Latch A

Reserved

Internal expansion

Internal expansion

Internal expansion

Internal expansion

External expansion

External expansion

External expansion

External expansion

Extended ext expansion

*If fitted*

**not fitted

System description

3000

I/O programming details

External latch A

External Latch A is a write only latch used to control parts of the floppy disc sub-system:

Service Manual

External latch B

The External Latch B is a write only register shared between several users who must maintain a consistent

RAM copy. Updates must be made with IRQ disabled.

System description 9

3000

Interrupts

The I/O system generates two independent interrupt requests, IRQ and FIQ. Interrupt requests can be caused by events internal to IOC or by external events on the interrupt or control port input pins.

The interrupts are controlled by four types of register: status, mask, request and clear. The status registers reflect the current state of the various interrupt sources.

The mask registers determine which sources may generate an interrupt. The request registers are the logical AND of the status and mask registers and indicate which sources are generating interrupt requests to the processor. The clear register allows clearing of interrupt requests where appropriate. The mask registers are undefined after power up.

The IRO events are split into two sets of registers, A and B. There is no priority encoding of the sources.

Internal Interrupt Events:

• Timer interrupts TM[0:1]

• Power-on reset POR

• Keyboard Rx data available SRx

• Keyboard Tx data register empty STx

• Force interrupts 1.

External Interrupt Events

• IRQ active low inputs IL[0:7] wired as (0-7 respectively) PFIQ, SIRQ, SLC1,NOT USED,

DCIRQ, PIRQ, PBSY and RII.

• IRQ falling-edge input IF wired as PACK

• IRQ rising-edge input IR wired as VFLY

• FIQ active high inputs FH[0:1] wired as FFDQ and

FFIQ

• FIQ active low input FL wired as EFIQ

• Control port C[3:5].

IRO status

A

Service Manual

10 System description

3000

IRQ status B Interrupt status FIQ

Service Manual

System description 11

3000

Control port

The control register allows the external control pins C[0:

5] to be read and written and the status of the PACK and VFLY inputs to be inspected. The C[0:5] bits manipulate the C[0:5] I/0 port. When read, they reflect the current state of these pins. When written LOW the output pin is driven LOW. These outputs are opendrain, and if programmed HIGH the pin is undriven and may be treated as an input.

On reset all bits in the control register are set to 1.

Service Manual

12 System description

3000 Service Manual

The sound system

The sound system is based on the VIDC stereo sound hardware. External analogue anti-alias filters are used which are optimised for a 20 kHz sample rate. The high quality sound output is available at a 3.5mm stereo jack socket at the rear of the machine which will directly drive personal stereo headphones or alternatively an amplifier and speakers. Two internal speakers are fitted, to provide stereo audio.

VIDC sound system hardware

VIDC contains an independent sound channel consisting of the following components: A four-word FIFO buffers sixteen 8-bit sound samples with a DMA request issued whenever the last byte is consumed from the FIFO. The sample bytes are read out at a constant sample rate programmed into the 8-bit Audio Frequency Register.

This may be programmed to allow samples to be output synchronously at any integer value between 3 and 255 microsecond intervals.

The sample data bytes are treated as sine plus seven-bit logarithmic magnitude and after exponential digital to analogue conversion, de-glitching and sign-bit steering, are output as a current at one of the audio output pins to be integrated and filtered externally.

VIDC also contains a bank of eight stereo image position registers each of three bits. These eight registers are sequenced through at the sample rate with the first register synchronised to the first byte clocked out of the FIFO. Every sample time is divided into eight time slots and the three bit image value programmed for each register is used to pulse width modulate the output amplitude between the LEFT and RIGHT audio current outputs in multiples of time slot subdivisions. This allows the signal to be spatially positioned in one of seven stereo image positions.

MEMC sound system hardware

MEMC provides three internal DMA address registers to support Sound buffer output; these control the DMA operations performed following Sound DMA requests from VIDC. The registers allow the physical addresses for the START, PNTR (incremental) and

END buffer pointers to a block of data in the lowest half

Megabyte of physical RAM to be accessed. These operate as follows: programming a 19-bit address into the PNTR register sets the physical address from which sequential DMA reads will occur (in multiples of four words) and programming the END pointer sets the last physical address of the buffer. Whenever the

PNTR register increments up to this END value the address programmed into the START register is automatically written into the PNTR register for the

DMA to continue with a new sample buffer in memory. A Sound Buffer Interrupt (SIRQ) signal is generated when the reload operation occurs which is processed by IOC as a maskable interrupt (IRQ) source.

The Memory Controller also includes a sound channel enable/disable signal. Because this enable/disable control signal is not synchronised to the sound sampling requests will normally be disabled after the waveforms which are being synthesised have been programmed to decay to zero amplitude; the last value loaded into the Audio data latch in the VIDC will be output to each of the Stereo image positions at the current Audio Sample rate.

IOC sound system hardware

IOC provides a programmed output control signal which is used to turn the internal speaker on or off, as well as an interrupt enable/status/reset register interface for the Sound Start Buffer reload signal generated by MEMC.

The internal speakers may be muted by the control line

SMUTE which is driven from the IOC output C5. On reset this signal will be taken high and the internal speakers will be muted.

The stereo output to the headphone socket is not muted by SMUTE and will always reflect the current output of the DAC channels.

System description 13

3000 Service Manual

The keyboard and mouse

The Keyboard and mouse connection to the ARM is via a keyboard controller and a serial link to the IOC. The

ARM reads and writes to the KART registers in the IOC.

The protocol is essentially half duplex, so in normal operation the keyboard controller will not send a second byte until it has received an ACK. The only exception to this is during the reset protocol used to synchronise the handshaking, where each side is expecting specific responses from the other, and will not respond further until it has those.

In addition to this simple handshaking system, the keyboard controller will not send mouse data unless specifically allowed to, as indicated by Ack Mouse, which allows the transmission of one set of accumulated mouse coordinate changes, or the next move made by the mouse. While it is not allowed to send mouse changes the keyboard controller will buffer mouse changes.

A similar handshake exists on key changes, transmitted as key up and key down, and enabled by

Ack Scan. At the end of a keyboard packet (two bytes) the operating system will perform an Ack Scan as there is no protocol for re-enabling later. Mouse data may be requested later by means of Request Mouse

Position (ROMP).

Key codes

The keyboard controller identifies each key by its row and column address in the keyboard matrix. Row and column codes are appended to the key up or down prefix to form the complete key code.

For example, Q key down — the complete row code is

11000010 (C2 hex) and the column code is 11000111 (C7 hex).

Note: Eight keys have N key roll over. The operating system is responsible for implementing two-key rollover, therefore the keyboard controller transmits all key changes (when enabled). The keyboard controller does not operate any auto-repeat; only one down code is sent, at the start of the key down period.

Data protocol

Data transmissions from the keyboard are either one or two bytes in length. Each byte sent by the keyboard controller is individually acknowledged. The keyboard controller will not transmit a byte until the previous byte has been acknowledged, unless it is the HRST code indicating that a power on or user reset occurred or that a protocol error occurred; see below.

Reset protocol

The keyboard controller restarts when it receives a

HardReSeT (HRST) code from the ARM. To initiate a restart the keyboard controller sends a HRST code to the ARM, which will then send back HRST to command a restart.

The keyboard controller sends HRST to the ARM if :

• A power-on reset occurs

• A user reset occurs

• A protocol error is detected.

After sending HRST, the keyboard controller waits for a HRST code. Any non HRST code received causes the keyboard controller to resend HRST.

The pseudo program below illustrates the reset sequence or protocol:

START reset

ON error Send HRST code to ARM then wait for code from ARM.

IF code - HRST THEN restart ELSE error

ON restart clear mouse position counters set mouse mode to data only in response to an RMPS request.

stop key matrix scanning and set key flags to up send HRST code to ARM

Wait for next code

IF code - RAK1 THEN send RAK1 to ARM

Wait for next code

IF code - RAK2 THEN send RAK2 to ARM

ELSE error

ELSE error

Wait for next code

IF code SMAK THEN mouse mode to send if not zero and enable key scan

ELSE IF code - SACK THEN enable key scanning

ELSE IF code - MACK THEN set mouse mode to send when not zero

ELSE IF code NACK THEN do nothing ELSE error

END reset

Reset sequencing

Direction Code Expected reply

Action on Action on Action if wrong reply timeout

(Sender) (Sender) unexpected

(Receiver)

ARM -> kb Hard reset Hard reset Resend

Kb -> ARM Hard reset Reset Ack 1 Resend

Resend

Nothing

Hard reset

Hard reset

ARM -> Kb Reset Ack 1 Reset Ack 1 Hard reset Hard reset Hard reset

Kb -> ARM Reset Ack 1 Reset Ack 2 Nothing Nothing Hard reset

ARM -> Kb Reset Ack 2 Reset Ack 2 Hard reset Hard reset Hard reset

14 System description

3000 Service Manual

Note, the on/off state of the LEDs does not change across a reset event, hence the LED state is not defined at power on. The ARM is always responsible for selecting the LED status. After the reset sequence, key scanning will only be enabled if a scan enable acknowledged (SACK or SMAK) was received from the ARM.

Data transmission

When enabled for scanning, the keyboard controller informs the ARM of any new key down or new key up by sending a two byte code incorporating the key row and column addresses. The first byte gives the row and is acknowledged by a byte acknowledge (BACK) code from the ARM. If BACK was not the acknowledge code then the error process (ON error) is entered. If the BACK code was received the keyboard controller sends the column information and waits for an acknowledge. If either a NACK, SACK, MACK or SMAK acknowledge code is received, the keyboard controller continues by processing the ACK type and selecting the mouse and scan modes implied. If the character received as the second byte acknowledge was not one of

NACK/MACK/SACK/SMAK then the error process is entered.

Mouse data

Mouse data is sent by the keyboard controller if requested by a ROMP request from the ARM or if a

SMAK or MACK have enabled transmission of nonzero values. Two bytes are used for mouse position data.

Byte one encodes the accumulated movement along the

X axis while byte two gives Y axis movement.

Both X and Y counts must be transferred to temporary registers when data transmission is triggered, so that accumulation of further mouse movement can occur. The X and Y counters are cleared upon each transfer to the transmit holding registers. Therefore, the count values are relative to the last values sent. The ARM acknowledges the first byte (Xcount) with a BACK code and the second byte

(Ycount) with any of NACK/MACK/SACK/SMAK. A protocol failure causes the keyboard controller to enter the error process (ON error).

When transmission of non-zero mouse data is enabled, the keyboard controller gives key data transmission priority over mouse data except when the mouse counter over/underflows.

Acknowledge codes

There are seven acknowledge codes which may be sent by the ARM. RAK1 and RAK2 are used during the reset sequence. BACK is the acknowledge to the first byte of a two byte keyboard data set. The four remaining types, NACK/MACK/SACK and SMAK, acknowledge the final byte of a data set. NACK disables key scanning and therefore key up/down data transmission as well as setting the mouse mode to send data only on ROMP request. SACK enables key scanning and key data transmission but disables unsolicited mouse data. MACK disables key scanning and keydata transmission and enables the transmission of mouse count values it either X or Y counts are non-zero. SMAK enables key scanning and both key and mouse data transmission. It combines

Code values

Mnemonic

HRST msb

1111 lsb

1111

Comments

One byte command, keyboard reset

RAK1

RAK2

RQPD

PDAT

RQID

1111

1111

0100

1110

0010

1110

1101 xxxx xxxx

0000

One byte response in reset protocol

One byte response in reset protocol

One byte from ARM, encodes four bits of data

One byte from keyboard, echoes four data bits of RQPD

One byte ARM request for keyboard ID

KBID

KDDA

KUDA

RQMP

MDAT

10xx

1100

1101

0010

Oxxx xxxx xxxx xxxx

0010 xxxx

One byte from keyboard encoding keyboard ID

New key down data. Encoded Row (1st byte) and column (2nd byte) numbers

Encoded Row (1st byte) and column (2nd byte) numbers for a new key up

One byte ARM request for mouse data

Encoded mouse count, X (byte1) then Y (byte2). Only from ARM to

BACK

NACK

SACK

0011

0011

0011

1111

0000

0001 keyboard

Ack for first keyboard data byte pair

Last data byte ack, selects scan/mouse mode

Last data byte ack

MACK

SMAK

0011

0011

0010

0011

Last data byte ack

Last data byte ack

LEDS

0000 Oxxx

Bit flag to turn LED(s) on/off

PRST

0010 0001

From ARM, one byte command, does nothing x is a data bit in the Code; e.g. xxxx is a four bit data field

System description 1 5

3000 Service Manual

the enable function of SACK and MACK.

While key scanning is suspended (after NACK or MACK) any

new

key depression is ignored and will not result in a key down transmission unless the key remains down after scanning resumes following a SACK or SMAK.

Similarly a key release is ignored while scanning is off.

Commands may be received at any time. Therefore, commands can be interleaved with acknowledge replies from the ARM. For example, keyboard sends KDDA (

1st byte), keyboard receives command, keyboard receives BACK, keyboard sends KDDA (2nd byte), keyboard receives command, keyboard receives

SMACK. If the HRST command is received, the keyboard immediately enters the restart sequence, (

ON restart). The LEDS and PRST commands may be acted on immediately. Commands which require a response are held pending until the current data protocol is complete. Repeated commands only require a single response from the keyboard.

ARM commands

Mnemonic

HRST

LEDS

RQM

RQID

PRST

RQPD

Function

Reset keyboard

Turns key cap LEDs on/off. A three bit field indicates which state the LEDs should be in. Logic 1 is ON, logic 0 (zero) OFF.

DO controls CAPS LOCK

D1 controls NUM LOCK

D2 controls SCROLL LOCK

Request mouse position (X,Y counts)

Request keyboard identification code. The computer is manufactured with a 6 bit code to identify the keyboard type to the ARM.

Upon receipt of ROID the keyboard controller transmits KBID to the ARM

Reserved for future use, the keyboard controller ignores this command

For future use. The keyboard controller will encode the four data bits into the PDAT code data field and then send PDAT to the

ARM.

Mouse interface

The mouse interface has three switch sense inputs and two quadrature encoded movement signals for each of the X axis and Y axis directions. Mouse key operations are debounced and then reported to the ARM using the Acorn key up / key down protocol. The mouse keys are allocated unused row and column codes within the main key matrix.

Switch 1 (left)

Switch 2 (middle

Switch 3 (right)

Row

code - 7 Column code -0

Row code - 7 Column code - 1

Row code - 7 Column code - 2

For example, switch 1 release would give 11010111 (D7 hex) as the complete row code, followed by 11010000 (DO hex) for the column code.

Note: Mouse keys are disabled by NACK and MACK acknowledge codes, and are only enabled by SACK and SMAK codes, ie they behave in the same way as the keyboard keys.

The mouse is powered from the computer 5 V supply and may consume up to 100 mA.

Movement signals

Each axis of movement is independently encoded in two quadrature signals. The two signals are labelled REFerence and DIRection (e.g. X REF and X DIR). The table below defines the absolute direction of movement. Circuitry in the keyboard decodes the quadrature signals and maintains a signed 7 bit count for each axis of mouse movement.

1

0

0

1

0

0

1

1

REF

Ink al

State

DIR REF

Next

State

DIR

0

1

1

0

0

1

1

0

1

1

0

0

1

1

0

0

0

0

1

1

1

0

0

1

Increase count by one for each change of state.

Decrease count by one for each change of state.

When count overflow or underflow occurs on either axis both X and Y axis counts lock and ignore further mouse movement until the current data has been sent to the ARM.

Overflow occurs when a counter holds its maximum positive count (0111111 binary). Underflow occurs when a counter holds its maximum negative count (1000000 binary).

16 System description

3000

Keyswitch mapping

Key

Name

Row code

Esc

F1

F2

F3

F4

F5

F6

F7

F8

F9

F10

F11

F12

Print

Scroll 0

Break 0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

-

1

8

9

6

7

4

5

2

3

0

-_

=+

/

*

#

£ 1

Backspc 1

Insert 1

Home 2

Pgup 2

Numlock 2

2

2

2

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

Key

Size

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

Col.

code

E

F

A

B

C

D

8

9

6

7

2

3

0

1

4

5

Notes

1

1

2

2

2

1,3

2

2

2

2

2

2

1

2

2

2

0

1

2

D

E

F

3

4

5

0

1

8

9

6

7

4

5

2

3

A

B

C

1

1

1

1

1

1,3

1

1,4

Service Manual

Key

Size

1

1

1

1

1

1

1

1

1.5

1

1

1.5

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1.75

1

1

1

2.25

1

1

;:

,*

J

K

G

H

L

Ctrl

A

S

D

F

5

6 return 4

4 4

+ 4

4

4

4

4

4

4

4

4

4

3

3

3

3

3

Key

Name

T

Y

I

U

O

\

P

[{

]}

Tab

Q

W

E

R

7

8

-

9

Delete 3

Copy 3

Pgdwn 3

3

3

3

3

2

2

2

2

2

3

3

3

3

2

2

2

2

2

Row

code

Col.

code

B

C

D

E

F

0

1

2

3

6

7

8

9

A

7

8

9

A

4

5

6

2

3

0

1

4

5

6 •

B

C

D

E

F

9

A

7

8

B

Notes

1

1

1

1

1

1,3

1

1

Row and column codes are in Hexadecimal.

Notes: 1 Key colour - dark grey

2 Key colour - red

3 Key position with N key roll over.

4

Green light emitting diode under key cap.

S y s t e m description 1 7

3000

Key

Name

B

N

M

,< shift

Z

X

C

V

.>

/?

shift

2

3 crsrUp 5

1 5

5

5

5

5

5

5

5

5

5

4

5

4

4

5

Row code

Caps

Alt

Space 5

5

5

Alt

Ctrl crsrLt 6 crsrDn 6

6

6 crsrRt

0

Enter

6

6

6

6

Key

Size

1

1

1

1

1

1

2.25

1

1

1

1

1

1

2.75

1

1

1.5

1.5

7.0

1

1

1.5

1.5

1

2.0

1

2.0

Row and column codes are in Hexadecimal.

Notes: 1 Key colour - dark grey

2 Key colour - red

3 Key position with N key roll over.

4 Green light emitting diode under key cap.

Col.

code

9

A

B

C

6

7

8

4

5

2

3

F

0

C

E

1

2

3

0

1

D

E

F

4

5

6

7

Notes

1,3

1,3

1

1,4

1,3

1

1

1,3

1,3

1

1

Service Manual

18 System description

3000 Service Manual

Floppy disc drive

The floppy disc drive used on the A3000 computer is a one-inch high drive, taking 3.5 inch floppy discs.

Performance

Power supply

Performance characteristics

Capacity

Track to track step rate

Seek settle time

Write to read timing

Power-on to drive ready

Power supply

Noise bandwidth

Maximum power

1 MB

(unformatted)

3ms

15ms

1200µs

1000ms

+5Vdc (+1- 5%)

0 - 30 MHz

2 Watts (continuous)

Power connector

The power connector is a 4-pin, 25mm pitch type. The

LED is ON when Drive Select and In Use are low or when Drive Select is low.

Pin

Signal

3

4

1

2

+5V

Ground

Ground

No connection

Interface connector

The interface connector is a 34-way 2 row, 0.1 inch pitch type, with pinouts as shown below:

Retn

Pin

Signal

1

3

5*

7*

9*

11*

13

23

25

27

29

31

33

15

17

19

21

2

4

6

8

10

12

24

26

28

30

32

34

14

16

18

20

22

*Optionally 5V

Signal

Disc change

In use

Drive select 3

Index

Drive select 0

Drive select 1

Drive select 2

Motor ON

Direction

Step/Dsc chg rst

Write data

Write gate

Track

0

Write protect

Read data

Side 1 select

Ready

Dir

(pcb)

I

O

O

I

I

O

O

O

O

O

O

I

I

O

I

I

O

Performance

Input voltage (47-53 Hz)

Input voltage (57-63 Hz)

Output voltage V01

Output current 101

Output ripple and noise VO1

Overshoot VO1

Over voltage plot VO1 (thrshld)

Surge output current 101

Surge output current duration

Efficiency

Total output power

Min Nom Max Units

198 220/

240

99 115

4.9

0.5

-

5

-

-

5.8

-

-

-

-

65

-

-

7.0

5.8

1.0

-

22

264 Vac

130 Vac

5.1

Vdc

4.4

Amps dc

50mV pk-pk

BW 0-50MHz

0.1Vdc

Vdc

Amps dc

Sec

%@max Id

Watts cont

29 Watts srge

Input voltage is selected by means of a link wire connected either to the pin marked '240' on the left-hand side of the power supply (when facing the front of the computer), or to the pin marked '120' in the top centre of the PSU. If the input voltage is changed, it is strongly recommended that a label, indicating the new voltage to which the computer has been set, is fixed to the outside of the case. A mains plug appropriate to the new supply should also be fitted, to prevent the computer from being powered up at the wrong voltage.

3

4

Pin

1

2

DANGER

DANGEROUS VOLTAGES ARE EXPOSED INSIDE

THE CASE OF THE COMPUTER WHEN THE

COVER IS REMOVED. THE COMPUTER SHOULD

BE DISCONNECTED FROM THE MAINS SUPPLY

BEFORE THE COVER IS REMOVED.

Floppy disc power connector

Signal

+5 V

0V

N.C.

N.C.

System description 19

3000

Links

Link Fitted Effect

LK22 Yes

Connection point for left channel audio speaker. P1 0V, P2 signal.

LK23 Yes

LK5 No

Connection point for right channel audio speaker. P1 0V, P2 signal.

Connection point for an external battery. (Only used if supply of on board NiCad becomes a problem.)

LK20 Yes

LK19 Yes

Used in conjunction with LK19 to select size of ROM devices.

Used in conjunction with LK20 to select size of ROM devices.

ROM LK19 LK20

512K 2-3

1M

2M

2-3

1-2

4M 1-2

2-3

2-3

2-3

1-2

LK25 Yes

Used to configure P5 of SK14

(RGB Video Socket) to be either 'VSync' or 'Mode'.

Fit shunt for 'VSync'

NF shunt for 'Mode'

(Mode is required by some

SCART TVs.)

LK24 Yes

Used to configure P4 of SK14

(RGB Video Socket) to be either 'HSync' or 'CSync'.

Shunt , 1-2 for 'HSync'

Shunt , 2-3 for 'CSync'

LK27 Yes

LK26 Yes

LK7 No

LK30 Not

LK28 Not

Used to invert 'VSync'.

Shunt fitted , VSync*

Shunt NF, VSync

Used to invert 'HSync'.

Shunt fitted , HSync*

Shunt NF, HSync

Test point for Non Volatile

Memory clock frequency.

P1 OV

P2 32.768KHz

Used in conjunction with LK29 and LK28 (&. 31 on Iss1) to provide the necessary signals

for a Genlock interface circuit.

P1 VS*

P2 HS*

P1 Ckvidc

P2 Clksys*

LK29 Not

LK31 Not

LK6 No

P1 0V

P2 Sink

P1 'Sup'

P2 0V

Test point for Non Volatile

Memory battery voltage.

P1 0V

P2 1.2V +/- 0.2V

20

Default

None

None

None

Shunt 2-3

Shunt 2-3 ie 1M

Shunt NF ie 'Mode'

Shunt 2-3 ie 'CSync'

Shunt NF ie 'VSync'

Shunt NF ie 'HSync'

None

None

Trk 1-2

(Shunt on Iss1)

Trk 1-2

(Shunt on Iss 1 )

None

None

Service Manual

Link Fitted Effect Default

LK8

LK9

No

No

LK10 No

LK11 No

LK12 No

LK13 No

LK1

LK2

LK3

LK4 No

LK17 N o t

LK18

LK16

LK21

LK14

LK15

LK32

No

No

No

Not

No

No

No

No

No

Used to set nationality id of the keyboard.

LK12 Trk ie UK

Used to optionally link 0V to the RFI Shield (Earth).

NF

NF

NF

Connection point for a design backup, self contained keyboard.

Keyboard reset P1 Krst *

P2 NC

P3 0V

P4 5V

P5 Krx'

PS K u '

From keyboard

To keyboard

Connection point for design backup, mouse to keyboard link.

P1 Xr X ref P5 Sw(1) Switch 1

P2 Xd X dir P6 Sw(2) Switch 2

P3 Yr Yref P7 Sw(3) Switch 3

P4 Yd Ydir P8 0V

Used in conjunction with LK18 .

to select ROM device type.

Selects the +5V power feed to the floppy disc drive to be via the data cable or by separate feed with PLS.

1-2 +5V via data cable

2-3 +5V via separate cable

NF

Trk 1-2

(Shunt on Iss1)

Used in conjunction with LK17 to select ROM device type.

ROM

512K EPROM

LK17 LK18

1-2 1-2

Non JEDEC 1 M ROM 1-2 1-2

Non JEDEC 1M EPROM 1-2 1-2

JEDEC 1/214M ROM/

EPROM 1 — 1

2 — 2

Used to select the design backup keyboard. See LK3.

Trk 1-2 ie Non

JEDEC

(Shunt on Iss1)

Trk 2-3 ie

Main K/B

1-2 Selects backup keyboard

2-3 Selects main keyboard

Trk 2-3 ie not via data cable

Trk 1-2

Trk 1-2 ie NMOS

Used in conjunction with LK15 to select the keyboard uC device type.

Device Type

8051 (NMOS)

LK14 LK15

1-2 1-2

80051 (CMOS) O/C 2-3

Provides access to RGB interface signals (Issue 1 only):

1 - Red

2 - Green

3 - Blue

4 - I-VCSYNCH

5 - VSYNC/MODE

6 - 0V

NF

Notes:

*

NF - Not Fitted

P1 - Pin 1

0/C - Open Circuit

Trk - Tracked

* Active low t Fitted on Issue 1 PCB

System description

3000

Plugs

PL1

PL3

PL4

Plug

PL5

PL6

PL2

Fitted Function/Specification

No

Floppy Disc Power Connector. If the power to the disc drive is to be supplied via the data cable, then PL5 must be fitted and the PSU free disc power socket must be connected to this plug with LK21.

No

P1 NC

P2 OV

P3 OV

P4 +5V

Floppy Disc Drive Data Connector. 34 way Box Header containing all the signals required by the internal floppy disc drive.

This interface is identical to that of the

Archimedes, except that the drive strength of some of the signals has been reduced as only one drive is supported. The pin numbering has been altered due to the incorrect orientation of the Archimedes layout.

Yes

Yes

Yes

Yes

Default powering is via a separate power connector from the PSU ( ie not up the data cable).

8

10

12

14

16

4

6

Pin

2

18

Signal

Dcirq*

In use*

Sel(3)*

Index'

Sel(0)*

Sel(1)*

Sel(2)*

W o r m '

Dirin*

Pin Signal

20

26

28

30

32

Step*

22Writedata*

24 Writegate*

Track00*

Writeprot*

Readdata*

Side1*

34 Ready'

1,3,13,15,17,19,21,23,25,27,29,31,33 all OV

(5,7,9,11 OV via LK21)

Faston tab for connection of Earth from the power supply.

Faston tab for connection of OV from the power supply.

Faston tab for connection of +5V from the power supply.

2

3

I

Pin

4

5

Serial Port (IBM PC-AT Pinout)

9 Way D-type plug.

Although the plug is fitted, the interface electronics are an upgrade consisting of:

IC 7 LT1133

IC 1 65C51

Signal

Dcd

Rxd

Txd

Dtr

OV

7

8

Pin

6

9

Signal

Dsr

Rts

Cts

Ri

Sockets

Service Manual

Notes: t Fitted to Issue 1 PCBs

Socket diagrams are viewed from outside the computer

System description 21

3000

Sockets

(contd)

Service Manual

22 System description

3000 Service Manual

Changes between Issue A and

Issue 1 PCBs

This manual covers A3000s produced with both Issue A and Issue 1 PCBs, and drawings for both versions are included. This section summarises the changes made during the production of Issue A boards, and the design changes made for Issue 1.

Modifications to Issue A PCBs

Component value changes

The chart below summarises the component value changes made during the production of Issue A PCBs, showing the first serial number changed.

(Unless otherwise stated, resistors are 5% SMD.)

Comp.

R133

R137

R502

R530

C75

C77

C80

C81

C82

C86

C88

C90

C91

C92

R98

R99

R101

R105

R129

R130

R131

R132

R88

R89

R91

R92

R93

R95

R97

R67

R68

R69

R70

R71

R81

R82

R85

R86

Issue A

150K 1%

150K 1%

33K

470R

33R

33R

33R

33R

33R

100K

6K8

22K

100p CPLT

2n7 CPLT

22n MPSTR

330p

330p

330p

22n MPSTR

100p CPLT

330p

2n7 CPLT

68R

68R

68R

68R

68R

33K

150K 1%

33K

150K 1%

33K

33K

150K 1%

33K

150K 1%

150K 1%

150K 1%

Serial no.

1000013

1000013

1000013

1000051

1000051

1000051

1000051

1000051

1000051

1000051

1000013

1004150

1000013

1000013

1000013

1000013

1000013

1000013

1000013

1000013

1000013

1000013

1000051

1000051

1000051

1000051

1000051

1000013

1000013

1000013

1000013

1000013

1000013

1000013

1000013

1000013

1000013

1000013

Changed to

22R

22R

22R

22R

22R

3K3

22K 1%

3K3

22K 1%

3K3

3K3

22K 1%

3K3

22K 1%

22K 1%

22K 1%

22K 1%

22K 1%

3K3

680R

22R

22R

22R

22R

22R

10K

4K7

1K

2n2 CPLT 10%

22n MPSTR 10%

100n MPSTR 10%

2n2 CPLT

2n2 CPLT

2n2 CPLT

100n MPSTR 10%

2n2 CPLT 10%

2n2 CPLT

22n MPSTR 10%

The following additional modifications were made during the production of Issue A PCBs:

Serial interface

10K resistor (5%, conventional type) was added as a ' pullup' to the rear of the PCB, connected between the signal Rii* (IC7 pin 18) and +5V (from serial number

1000001).

Video genlocking

The tracks on the underside of the PCB, between the pins of both LK28 and LK29, were cut. 2-pin wafers were fitted to LK28, 29 & 30, and shunts to LK28 and

29 (but not LK30) (from 1000251).

I

2

C-bus

access

Two 5-way headers (0800,486) were fitted to SK8 and

SK9 (from 1000251).

JEDEC & non-JEDEC EPROMs

To permit the use of JEDEC and non-JEDEC

EPROMs, tracks on the PCB, between the pins of both LK17 and LK18, were cut. 2-pin wafers were fitted to LK17 & 18, and shunts fitted to LK17 and 18 (from

1000251).

Fixing of 64W connector

Two rivets (Avdel 11070312) were added to the mounting holes of the 64-way expansion connector.

Design changes made between Issue

A and Issue 1 PCBs

Serial interface

The 'strapped on' resistor (see above) was replaced by a permanent resistor (10K SMD 5%) — R144.

Signal conditioning

R141, R142 and R143 have been added (22R SMD 5%) to REF8M, RA9 and IORQ. R134 has been moved to accomodate these.

A capacitor C116 (2n7) has been added between SW3 and OV.

Video genlocking

LK28 & 29 tracks have been deleted (see above). LK

28, 29 & 30 moved.

LK31 has been added. This allows access to the VIDC supremacy bit (pin 28) and GND.

JEDEC & non-JEDEC EPROMs

The tracks between the pins of LK17 & 18 have been deleted (see above).

System description 23

3000

RGB & SYNC

A

6-way connector (LK32, not fitted) has been added to RGB & SYNC for internal access.

Production changes

The components R550, C55, C78, C500, C501 and

C504 have been moved to facilitate production.

R145 (4K7 SMD 5%) has been added between 1C2 pin

31 and +5V to accomodate ATE.

Test points have been added to the following lines:

ARM20-MEMC3

MEMC38

MEMC39

MEMC40

MEMC41

MEMC42

(R129-R132 have been moved to accomodate these test points.)

Service Manual

24 System description

3000

A3000 expansion

Internal expansion

DANGER

DANGEROUS VOLTAGES ARE EXPOSED INSIDE

THE CASE OF THE COMPUTER WHEN THE

COVER IS REMOVED. THE COMPUTER SHOULD

BE DISCONNECTED FROM THE MAINS SUPPLY

BEFORE THE COVER IS REMOVED.

7

8

9

10

11

12

13

14

15

16

17

3

4

5

Pin no

SK3

1 +5V

2 PWE*

6

PS1*

CLK2

LA[2]

LA[3]

BD[7]

RST*

0V

+5V

BD[0]

BD[1]

BD[2]

BD[3]

BD[4]

BD[5]

BD[6)

The following internal upgrades are currently available for the A3000 computer:

• User port / MIDI internal expansion card

• 1 Mb Ram upgrade

• Serial port

• Econet module

Internal upgrades must be fitted by an Acorn Dealer or

Approved Service Centre.

Interface

The electrical signals available on the internal expansion are a subset of those described in 'A Series podules', available from Acorn Customer Service as

an Application Note, or on the SID system (Doc Ref

0310101).

The connection is via two 17-way 0.1 inch pitch connectors and two 5-way 0.1 inch connectors (the latter fitted as standard to Issue 1 PCBs and later).

Expansion cards should use 0.025 in square pin headers.

Expansion bus connectors

LA[6]

LA[7]

0V

LA[8]

LA[9]

LA[10]

LA[11]

SK11

0V

+5v

PRE*

PR/nW

LA[4]

LA[5]

LA[12]

LA[13]

PIRQ*

0V

SK8

C[0]

C[1]

BI

IORQ*

IOGT

SK9

0v

REF8M

PFIQ*

Ms[1]*

+5V

Note: Pin 1 is at the righthand end when viewed from the front of the computer.

A3000 expansion

Service Manual

The interface is configured as 'Podule 1, Module 1'.

It is recommended that the load on each signal does no exceed 3HCT gates or that stated in 'A Series podules'. Any upgrade must be able to drive at least 7

HCT and 3 TTL loads on the data bus.

Power supply

The maximum power available from the +5V rail is

600 mA. The maximum dissipation inside the case is

0.5W (100mA).

Mechanical

The rear panel required is shown in the drawing at the back of this manual. The size of the User Port/MIDI expansion card PCB and position of the connectors are also shown in the drawing at the back of the manual.

User port/MIDI expansion card (UPM)

Introduction

The A3000 User Port / MIDI expansion card fits inside the computer, and provides:

• An 8-bit User Port, largely compatible with the User

Port interface on the BBC Model

B and Master 128 microcomputers (and with the User Port on the

Archimedes

I/O expansion card).

MIDI (Musical Instrument Digital Interface), with IN,

OUT and THRU connections, compatible with the

International MIDI Association specification.

Main components

• 65C22 VIA for the User Port

• 2691 UART for the MIDI

• 27128 EPROM containing firmware and ID byte.

2 5

3000 Service Manual

UPM block diagram

Comparison with Archimedes expansion cards

ARCHIMEDES I/O EXPANSION CARD

• The VIA is at the same address and clocked at the same speed. Port A PA<0..2.> is used to page

ROM. These are the same as the UPM when set for

2764/27128.

• The User port is the same (Port B). The VIA interrupts go through a link, which is not normally fitted.

• The MIDI section is not the same.

• The ADC and 1 MHz bus are not fitted to the UPM.

MIDI EXPANSION CARD

• The UART is the same (Signetics 2691), but is at a different address (see below).

• The ROM page latch is not the same.

MiDi Podule

UPM upgrade

LA13

1

1

LAl2

0

1 offset address

82000

83000

Addresses of main system components

Address

&0000-1FFC

Component

ROM/EPROM 271 28 as standard (16k x

8 bit). Larger EPROMS can be fitted if the links marked X are cut between pins

1 & 2, and relinked 2 to 3.

Eprom size

2764

27128

27256

27512

1M bit (JEDEC)

2m bit

4m bit

LK 1 LK 2 LK3 LK4

X

X

X

X

X

X

X

X

X

X

X X

&2000-2FFC

&3000-3FFC

Contains the iD byte 63 (dec).

The start-up information must be at the top of the ROM.

VIA 65C22 - 2Mhz part.

Port A PA<7..0> used to page the ROM.

CAs Not Used.

Port B PB<7..0>, CB1 and CB2 for the

User Port.

Use 2Mhz synchronous cycle to access the VIA.

The interrupt output connects directly to

PIRQ*.

No User Port interrupt handler provided.

UART 2691 - For the MiDi interface.

26 A3000 expansion

3000

Fitting an Internal expansion card

This procedure covers the fitting of an internal expansion card, such as the User Port / MIDI expansion card. This work should only be carried by

Acorn Dealers or Approved Service Centres:

1 Follow the procedure for removing the cover of the computer given in the next chapter.

2 Unscrew the two machine screws holding the rear blanking plate in place, and remove the plate:

Service Manual

1Mb RAM upgrade

The A3000 computer RAM can be upgraded from 1Mb to 2 Mb by the addition of a 1Mb RAM module which plugs into the main PCB.

Fitting a RAM upgrade

1 Follow the procedures detailed in the next chapter for the removal of the computer cover and the keyboard.

2 To fit earlier RAM upgrades with securing lugs, remove two PCB retaining screws and plug the upgrade module, in a vertical position, into the board. Later upgrades, with no fitting lugs, simply push into the connectors on the PCB:

3 Plug the expansion card into the connectors on the

PCB, and press firmly home:

3 Replace the screws securing the PCB and the upgrade module.

4 Replace the keyboard and the cover of the computer.

5 Run the dealer test software to test the correct function of the computer and the upgrade, and of any other upgrades fitted.

4 Replace the two screws holding the expansion card backplate, and secure firmly.

5 Replace the cover of the computer.

6 Run the dealer test software to test the correct function of the computer and the upgrade, and of any other upgrades fitted.

Keep the rear panel blanking plate with the computer, in case the expansion card is removed later.

A3000 expansion 2 7

3000 Service Manual

Serial port upgrade

Introduction

The A3000 computer is fitted with a 9-way D-type serial connector on the back panel, but this is not functional until a serial port upgrade kit has been fitted by an Acorn Dealer or Approved Service Centre.

Only Acorn Serial Port Upgrade kits should be used.

The A3000 serial port upgrade consists of a serial processor chip and a line driver chip, which fit into existing sockets on the PCB.

Connector pinouts

Fitting the Acorn A3000 serial port upgrade

WARNING: It is a recommended requirement that anti-static precautions should be utilised at all levels of servicing, ie antistatic matting and wriststraps.

1 Follow the procedures in the next chapter for the removal of the cover and the keyboard.

2 Remove the Econet module and the User Port /

MIDI expansion card, if fitted.

3 Insert the 28-pin IC 65C51 into socket IC1, and the 24pin IC LT1133 into socket IC7. The notched ends of the ICs should face towards the left hand side of the

PCB (viewed from the front of the computer) :

28

4 Fit the serial number label to the PCB near the upgrade ICs.

5 Refit any modules and expansion cards removed in step 2 above, and replace the cover of the computer.

6 Remove the label 'Serial not fitted' from the rear panel.

7 Run the dealer test software to test the correct function of the computer and the serial port, and of any other upgrades disturbed during this installation.

A3000 expansion

3000

Fitting an Econet module

1 Follow the procedure in the next chapter for removing the cover of the computer.

2 Plug the module onto the PCB connectors:

3 Replace the cover of the computer.

4 Run the dealer test software to test the correct function of the computer and the Econet module, and of any other upgrades fitted. Refer to the appropriate Econet file server Manager's Guide for instructions on setting the station id.

Service Manual

External expansion

Interface introduction

The A3000 computer supports an external expansion card (podule) interface, although with some minor differences from other ARM based systems:

• Single +5Volt power supply rail, rated at a maximum of

1 Amp (no +12 or –5 Volt rails provided)

• No support for Co-Processor type cards

• The external expansion card is in software slot 0

• The podule must be capable of driving 3 TTL and

7HCT loads on the data bus.

Refer to the application note 'A series podules' ( referenced at the start of this chapter) for a full podule interface specification.

Physical dimensions

As the podule is external to the computer enclosure there is no real limit on the size of the unit. Care should be taken not to block off any of the other expansion ports on the rear of the computer.

Fitting an expansion card

WARNING

Power down the computer before fitting or removing an external expansion card.

It is anticipated that expansion cards will be fitted into a suitable external expansion card unit. Slots are provided underneath the case of the computer, into which a tongue in the case of the expansion card unit can locate.

Tapped holes are provided in the backplate of the computer to enable the expansion unit to be secured to the computer with two M6 screws.

Connector

The podule interface is provided via a 64-way DIN

A+C 41612 socket fitted at the rear of the computer:

A3000 expansion

The connections to the interface are shown overleaf.

2 9

30

3000

External expansion connections

ROW C

PIRQ*

PFIQ*

S[6]*

C[1]

C[0]

S[7]*

PS[0]

IOGT*

IORO

BL*

0V

CLK2

CLK8

REF8M

+5V reserved reserved

0V reserved

0V

0V reserved

MS[0]* reserved reserved reserved reserved reserved

FIST*

PR/W*

PWE*

PRE*

Pin ROW A

16 BD[15]

17 BD[14]

18 BD[13]

19 BD[12]

20 BD[11]

21 BD[10]

22 BD[9]

23 BD[8]

24 BD[7]

25 BD[6]

26 BD[5]

27 BD[4]

28 BD[3]

29 BD[2]

30 BD[1]

31 BD[0]

32 +5V

3

4

1

2

5

0V

LA[15]

LA[14]

LA[13]

LA[12]

8

9

6

7

LA[11]

LA[10]

LA[9]

LA[8]

10 LA[7]

11 LA[6]

12 LA[5]

13 LA[4]

14 LA[3]

15 LA[2]

Row C description

Ground

Ground

Ground

MEMC Podule select

Reset (see note below)

Read/not write

Write strobe

Read strobe

Normal interrupt

Fast interrupt

12C serial bus clock

I2C serial bus data

External Podule select

Simple Podule select

MEMC Podule handshake

MEMC Podule request

VO data latch control

Supply

2MHz Synchronous clock

8MHz Synchronous clock

8MHz Reference clock

Supply

Note: The RST* signal is the system reset signal, driven by IOC on power-up or by the keyboard reset switch. It is an open-collector signal, and expansion cards may drive it also if this is desirable. The pulse width should be at least 50ms.

Service Manual

A3000 expansion

3000

Disassembly and reassembly

Service Manual

DANGER

DANGEROUS VOLTAGES ARE EXPOSED INSIDE

THE CASE OF THE COMPUTER WHEN THE

COVER IS REMOVED. THE COMPUTER SHOULD

BE DISCONNECTED FROM THE MAINS SUPPLY

BEFORE THE COVER IS REMOVED.

Removing the cover

To remove the cover from the computer, follow this procedure:

1 Disconnect all peripherals and unplug the computer from the mains supply.

2 Unplug the mouse connector from the underside of the computer.

3 Remove the centre fixing screw on the underside of the case:

5 Unhook the two clips and slightly lift up the back of the cover, pivoting on the front.

6 Locate the three rectangular holes on the front underside of the case. Insert a screwdriver into the rear edge of each of these holes in turn. Push and twist until the catch comes free of the lower case.

7 Repeat this procedure for the other two holes until the cover lifts clear.

Fitting is the reverse of the above procedure, ignoring step six.

Removing the keyboard

WARNING

The keyboard connector can be damaged by incorrect handling. Hold it by the white plastic strengthening strip only. Do not touch the track faces or apply pressure to the cable itself.

1 Follow the procedure for removing the cover.

2 Unplug the keyboard connector, and lift the keyboard out from the lower case.

Fitting is the reverse of the above procedure.

Removing the floppy disc drive

1 Follow the procedure for removing the cover.

2 Disconnect the power supply cable from the drive, and the ribbon cable from the PCB.

3 Remove the keyboard (see above).

4 Turn the lower case upside down and support the drive on a foam pad.

5 Remove the four recessed drive fixing screws:

4 Remove the two screws from the clips at the rear of the computer:

Disassembly and reassembly 31

3000

6 Tturn the case back up again. Lift the drive clear.

Fitting is the reverse of the above procedure.

Removing the PSU

1 Follow the procedures for removing the cover and the keyboard (above).

2 Disconnect the two faston connectors from the PCB, the connector on the PSU and the power cable to the disc drive.

3 Remove the warning sticker on top of the PSU cover. If the PSU is held in place by a plastic rivet, release the rivet jaws by pushing the pin in the centre of the jaw down, and then push the rivet itself down. If a selftapping retaining screw is fitted, this should be should be unscrewed. The PSU and its cover will then lift out: the case:

Service Manual

Fitting is the reverse of the above procedure — insert the

PCB into the clips at the front edge of the case before lowering into place. Care should taken to ensure that the

RESET key is not damaged.

Replacing the battery

The battery providing current to the real-time clock and battery-backed RAM is soldered to the PCB:

Replacing the PSU

When replacing the PSU, ensure that the plastic insulating film is replaced underneath the PSU, and that the the cover is correctly located. Take care not to overtighten the self-tapping screws.

Removing the PCB

1 Follow the procedures above for the removal of the cover, the keyboard, floppy disc drive and the

1MByte RAM, if fitted.

2 Remove the power leads at the point where they connect to the PCB (red +5V and black OV).

3 Disconnect the two speaker leads, and remove the

RH speaker (viewed from the front).

4 Unscrew the three self-tapping screws retaining the

PCB, and the PCB and rear panel will lift out of

32

If this needs replacing, it will have to be removed using a soldering iron and a desoldering gun. Repair sites lacking the equipment and experience in this type of work should not attempt to carry it out, or damage to the PCB may result. Care should be taken to avoid shorting the battery

— connecting the positive and negative terminals — even on a battery being discarded.

Disassembly and reassembly

3000

Fault diagnosis

Introduction

This chapter is a guide to the diagnosis and repair of basic faults in the A3000 computer system.

It consists of algorithms to enable you to trace & remedy faults in a 'dead' computer, followed by instructions for running the functional test software, designed to isolate faults in a computer which is working.

The next chapter 'Main PCB fault diagnosis and repair' is designed to help those repair centres equipped to do so, to diagnose and repair faults at component level on the main PCB.

Test equipment required:

• 100 MHz oscilloscope.

• DC Voltmeter.

• Earth Continuity tester.

• Serial port loopback plug (part number 0280,087).

See the Appendix for details of the plug.

• 32 ohm impedance headphones.

• IC extraction tools.

• Antistatic matting and wrist straps.

• Standard hand tools.

DANGER

Service Manual

AFTER REFITTING OR FITTING A

REPLACEMENT ASSEMBLY, CARRY OUT

EARTH CONTINUITY TESTING ON THE

ASSEMBLED COMPUTER ACCORDING TO THE

PROCEDURE GIVEN IN APPENDIX B.

WARNINGS

• Repairs to multi-layered PCBs:

The main PCB is a four-layer board.

Components should only be removed from the board using equipment specifically designed for this purpose. For details of suitable equipment available, contact Acorn Customer Service.

• Repairs to surface-mounted devices:

The ARM, MEMC, IOC AND VIDC ICs on the

A3000 PCB are surface-mounted components.

Do not attempt to remove them from the board and replace them unless you have the experience and the correct equipment to do so.

• System clock failure:

If the computer is powered on for more than a few seconds and there is no system clock, there is a risk that all four ARM chips may be damaged, as well as the RAM.

• Faulty MEMC: if MEMC is faulty or the RAS/CAS signals are not being generated, the RAM may be damaged if the machine is left on too long. If you suspect a fault in these areas, scope the RAS and CAS lines for a few seconds in order to make sure that they are still active, then turn the machine off. Do not leave the computer on for more than a few seconds at a time.

• Antistatic precautions:

It is a recommended requirement that anti-static precautions should be utilised at all levels of servicing, ie antistatic matting and wrist-straps.

Fault diagnosis 33

3000

Checking a 'dead' computer

Service Manual

34 Fault diagnosis

3000

Checking the sound system for faults

Note: Both SoundDMA and SoundChannel modules must be active (ie, not unplugged) before starting this test.

Service Manual

Fault diagnosis

*TEST PROGRAM

10 REM > Check all channels

20 VOICES 8

30 FOR channel-1 TO B

40 OSCLI("Channelvoice "+STRS(channel)+" "+STR$(2))

50 NEXT

60 FOR channel - 1 to 8

70 SOUND channel, -15, 100,24

80 PRINTchannel

90 k-GET

100 NEXT

RUN PROGRAM.

PRESS A KEY AND REPEAT EIGHT TIMES.

PRiNTS CHANNEL NUMBER TO THE SCREEN

AND PLAYS VOICE 2 FOR EACH CHANNEL.

3 5

3000

Functional tests

Notes:

• Please read the following section 'General test procedure' before you carry out any of the tests.

• For details of how to repair the main PCB, see Main functional test.

Introduction

The A3000 test disc enables the engineer to test the functionality of the computer and Acorn upgrades, and to isolate any faults which may appear. The functional test cannot of course be run on a 'dead' computer — see the previous section for advice on diagnosing faults in 'dead' computers.

General test procedure

The A3000 computer, mouse, expansion cards, Test disc, Port Tester assembly and Econet cables are designed and specified by Acorn Computers Ltd and may not be changed without written consent from

Acorn. All items should be complete with the correct cables so that you can connect them to the A3000 computer.

Equipment required

• A3000 computer to be tested

• Mouse

• 3.5 inch Test disc, part number 0280,032

• Two ADFS 800k 'D' formatted, write enabled, 3.5 inch discs, to be labelled Scratch Disc and Data disc.

• Serial port loopback' plug for A3000 (Acorn part number (0280,087). See the Appendix for details.

• Epson FX80 or Olivetti JP101 printer

• Pair of 32 ohm stereo headphones

• Mono monitor

• Analogue RGB monitor.

Note: You can replace the specified printers with any other manufacturer's direct functional equivalent (in terms of BOTH hardware interface and software).

Removing the top cover of the computer main unit

Remove the top cover of the A3000 computer as detailed in the previous chapter 'Disassembly and

Assembly'.

Connecting up the equipment

Connect the:

• serial port 'Ioopback' plug to the 'SERIAL' socket

• printer to the 'PARALLEL PRINTER' port

Service Manual

• headphones to the 'Headphones 32 ohm' socket

• monochrome monitor to the 'MONO VIDEO' socket

• analogue RGB monitor to the 'ANALOGUE RGB' socket

• monitors to the mains supply

• A3000 computer to the mains supply.

Connecting and disconnecting the power

• You must CONNECT the power only when you have made all the other connections

• You must DISCONNECT the power before removing any other connections.

Validating the test equipment

Before carrying out any of the tests in this section, validate the test equipment using a known good system. If the test equipment fails, you should repair the test equipment and retest on a known good part.

Before you start

Before the start of each day or testing session, you must first:

• Adjust the colour monitor to ensure adequate contrast and brightness

• Inspect all the mechanical parts of the test equipment and replace any parts as necessary.

Also, if required:

• Ensure that the printer has sufficient paper

• Connect the printer to the mains supply. Do NOT turn on.

Saving and restoring the CMOS RAM

The tests alter the contents of the battery backed RAM that holds the A3000's configuration data. These must be saved before any of the tests is run, and restored when the last test is over.

1 Insert the Test disc into the floppy disc drive.

2 Switch on the monitors and computer.

3 Type F12 to get to the command line prompt.

4 At the RISC OS supervisor prompt (an asterisk) type the following;

DRIVE 0

CMOSLS

5 When prompted, replace the Test disc with an

ADFS 800k write enabled disc, the Data disc.

6 Type 'S' to save the contents of the RAM, or 'L' to load a previously saved copy of the RAM.

7 Type the filename to use.

8 When prompted, replace the Test disc in the drive and press the space bar to continue.

9 Put the data disc in a safe place. Do NOT use this disc for the later floppy disc test.

10Type 'Q' to quit this option.

36 Fault diagnosis

3000 Service Manual

Carrying out the tests

There are two types of tests – subjective and non subjective. The test program passes or fails the equipment on the non-subjective tests; however, you must judge whether the equipment passes or fails the subjective tests. It is a good idea for testers to familiarise themselves with the correct results given by a known good computer. In this way they will be in a better position to judge faulty results.

Performing soak tests

At the successful completion of a main PCB functional test, you should carry out a soak test. To do this, select the relevant option and then insert the scratch disc when prompted. The test runs for 12 hours. When the test is running the Caps Lock and Num Lock LEDs will flash, provided that no error has occurred. If a disc error occurs all the LEDs will be off (see table below); the disc error is also displayed on the screen. If the test is completed without an error then the Scroll Lock LED will flash and the Caps Lock and Num Lock LEDs will be extinguished.

Num Lock Caps Lock Scroll Lock Screen

No errors

Error

Finished

Flashing

Off

Off

Flashing

Off

Off

Off

Off

Flashing

Running

Fail

Pass

Warning

During the soak test the unit under test should not be subjected to mechanical shock or movement. The unit shall not be turned off unless the test has terminated – the pass or fail message will be displayed.

Safety check

After repairing a unit, and after the soak test, you should carry out the earth continuity check mentioned at the start of the chapter, followed by a further runthrough of the functional test, in case the earth check causes malfunction in the computer.

Repairing faults

When repairing an A3000 computer, you should repair the faults in the order in which they occurred during the test (ie repair the first recorded failure FIRST).

For further information on checking for faults and carrying out repairs, refer to the appropriate section of this manual.

Restoring the CMOS RAM

After passing the soak test, the unit under test needs to be restored to the customer's configuration. This is carried out by reloading the CMOS RAM from the data disc saved earlier, by selecting the

Load/Save CMOS RAM option from the main menu. Then select the

Load option after inserting the Data disc when prompted. See 'Saving and restoring the CMOS

RAM' above for details of the test procedure.

Packing

After servicing, repack the A3000 computer in its box.

To avoid damage, do NOT send the computer through the post or by courier unless it is in its original packaging. The original packaging should be checked for damage to the outer casing and poly inserts.

Fault diagnosis 37

3000 Service Manual

Main computer tests

Running the test

Run the main functional test software as follows:

Ensure that CMOS RAM contents have been saved to disc by using the

Load/Save CMOS RAM option described above. Then restart the system with a delete-poweron. To perform a delete-power-on, do the following:

Whilst holding down the <Delete> key, turn the computer on. Note that the <Delete> key needs to be held down for several seconds. The screen should display the

DESKTOP environment.

Note: A useful indication of the success of the delete-power-on sequence is the momentary appearance of a red border area on the screen.

Insert the Test disc. Hold down Ctrl, Shift and *, then press Break. The program will load from disc.

The 'Dealer Test Menu' is displayed:

A3000 Dealer Test Menu

1

2

3

4

Main Computer

Upgrades

Load/Save CMOS RAM

Soak Test

5

Quit

SELECT OPTION :

Machine identification test

Select the option

Main computer.

After selecting and loading the required test program, the

A3000 computer cycles through a series of tests beginning with the computer type/model test. This test is extremely fast and the type and model number of the computer is displayed immediately:

This computer is a

BBC A3000

CHECK DESCRIPTION

THEN PRESS <SPACE> TO CONTINUE repair.

If an RS232 or 1Mb RAM upgrade is fitted but not mentioned, switch off the unit under test, remove the upgrade and then continue the test. When the computer has passed the main test sequence, power down the unit and re-install the upgrade and then run the relevant upgrade test.

If the description is the same, press the space bar to continue to the next test.

Test options

TEST

OPTIONS

A AllTests Except Printer

B AllTests and Epson Printer

C AllTests and JP101 Printer

SELECT

OPTION

Select the test appropriate to the printer fitted.

If

you do not want to test the printer and do not need a printout of the results, you can select the 'All Tests Except Printer' option.

Memory

The functional test continues by testing the memory.

The screen clears and displays the following messages:

Memory test

Phase one: incrementing pattern ....

Phase two: TRUE hierarchy ............

Phase three: FALSE hierarchy ........

Phase four: Cycling bits ............

PASSED/FAILED message

Press SPACE to continue.

A failed message will end the tests.

Action if test falls

Change the main PCB, or run the main memory test in the next chapter, and repair as necessary.

If the test has PASSED, press the Space Bar to continue the test.

You should:

1 Check that the description displayed on the screen is correct.

2 If

Unknown UUT is displayed then there is a memory fault.

Action If test falls

Change the main PCB, or see the next chapter for

38 Fault diagnosis

3000 Service Manual

Battery backed RAM

The test continues by testing battery backed RAM.

The following message is displayed on the screen:

Battery Backed Ram (BBR) test running.

Reading BBR into main memory.

Checking read/write function of BBR.

Re—loading configuration parameters.

PASSED/FAILED message

PRESS <SPACE> TO CONTINUE

Press the Space Bar to continue the test.

Action if test falls

Check battery and connections, and check battery is charged. Re run the test. if the test still fails, replace the main PCB, or see the NVM and RTC tests in the next chapter, and repair as necessary.

Time

The functional test continues by testing the time and date settings. A series of options is displayed on the screen:

DO YOU WANT TO ?

1. CHECK THE DATE AND TIME

2. SET THE DATE AND TIME

3. CHECK THEN SET THE DATE AND TIME

PRESS 1 OR 2 OR 3

The normal procedure is to select option 1. If you want to reset the time or date you would select 2 or 3. For example, you can:

1 Type 1 to check the date and time.

2 Check that the time is correct and the seconds are incrementing correctly.

3 To continue with the test, press the Space Bar.

Loudspeaker

The functional test continues by testing the operation of the loudspeakers. A short repeating sequence of four notes is played, first through the left and then the right speaker. The following message is displayed:

LOUDSPEAKER TEST

LISTEN AND CHECK SOUND

THEN PRESS <SPACE> TO CONTINUE

You should:

1 Listen to the sequence of notes.

2 Check that the first four notes come from the left speaker and the second four from the right.

3 Check that the sound produced is correct. This is a subjective test, so if you detect any deviation, make a note of the fault.

Action if test falls

If no sound, or sound from one speaker only, then check speaker connections. If it still fails, substitute known good speakers and re-test. If the sound comes from one speaker only check that the headphone plug is inserted correctly. If test still fails, replace the main

PCB, or carry out the Audio test in the next chapter, and repair as necessary

To continue with the test, press the space bar.

Headphones

The Functional test continues by testing the operation of the headphones. The following message is displayed as the test proceeds:

HEADPHONE TEST RUNNING

LISTEN AND CHECK SOUND

THEN PRESS <SPACE> TO CONTINUE

The test consists of a repeating sequence of eight musical notes. The first four notes are played on one headphone and the next four notes on the other headphone.

1 Put on the headphones.

2 Listen to the sequence of notes.

3 This is a subjective test, so if you detect any deviation in either headphone, note down the fault.

Action if test falls

If no sound or poor/faulty sound on known good headphones, replace the main PCB, or carry out the

Audio test in the next chapter, and repair as necessary. Ensure the headphones are plugged in correctly.

To continue with the test, press the Space Bar.

Standard colour monitor

This test consists of a series of screen displays. You proceed through the test at your own pace.

The first display consists of a series of white lines radiating from the top lefthand corner. A cursor, in the shape of a bird, travels across the screen, starting from the bottom left and finishing at the top right. The features to check are:

• the accuracy of the lines

• the movement and integrity of the cursor.

Fault diagnosis 39

3000

This is a subjective test, so make a note of any faults.

When you have finished looking at the screen display, press the Space Bar to move to the next display.

The next screen displays consist of four test cards.

There is a test card for each of the three colour guns, and a 'grey scale' to test the three guns. The four test cards are:

• Red scale

• Green scale

• Blue scale

• Grey scale.

Each test card consists of 16 concentric circles beneath a horizontal band which is divided into 16 sections. A pale border highlights the left most eight sections of the band in order to distinguish the band from the background. The whole test card is surrounded by a contrasting border.

The purpose of the cards is to display 16 shades with the shade of the border as the middle of the range. You should observe:

• the 16 shades displayed

• the mid-coloured border

• the quality of the 'grey scale' display

• the integrity of each test card.

This is a subjective test, so make a note of any faults which you detect and when you are ready to continue press the Space Bar.

Action If test falls

if display rolls or is unstable, perform a Delete Poweron until the correct default value is obtained. The computer may have lost its configuration value for

SYNC. Type at the keyboard:

CON. SYNC 1 (RETURN)

Press RESET and see if if any change occurs. If no improvement is visible, change the main PCB, or perform the Video tests in the next chapter, and repair as necessary.

Keyboard Functional test

LEDs

This test checks that the LEDs (Caps Lock, Scroll

Lock and Num Lock) are working.

Keys stuck

During this test, any keys or mouse buttons which are in a permanently closed position (ie stuck down; are displayed on the screen.

If

any keys are permanently closed, then it will be impossible to continue the test.

If everything is normal and no keys are stuck, then the last key pressed clears the screen and the Test program passes straight on to the next test.

Service Manual

To carry out this test:

1 Follow the instructions which appear on the screen.

These tell you when to check that each LED is ON and OFF.

2 Note down any LED failures before continuing the test. These are not recorded.

3 After each set of instructions press Break to move to the next instruction.

Mouse

This tests the three buttons on the mouse and the movement of the mouse to the left, right, up and down.

Each of the mouse buttons (ie left, middle, right) are displayed on the screen in turn, together with a pointer.

You should:

1 Move the mouse, until the pointer is within the box on the screen, then press the button displayed on the screen.

2 The box displayed on the screen should disappear and the next button appear.

If the button cannot be made to disappear then it will be

IMPOSSIBLE to continue the test. You should repeat the test with the known good mouse to isolate the fault to either the keyboard or the mouse. Replace faulty components, then retest.

If everything is normal, the program moves on automatically to the next test.

Keys

The screen clears to show a representation of the keys in the main keyboard area. You need to test each key in turn in the correct order, ie work from the bottom line of the keyboard and from left of the keyboard to the right:

1 Press Caps Lock.

2 Check that the picture of the Caps Lock key disappears from the screen.

3 Press Alt and check that the picture of the Alt key disappears from the screen. If the picture of the key does not disappear from the screen then leave a small delay before pressing the next key.

If the screen stops clearing the characters as you press the keys, go back to the lowest, leftmost key remaining on the screen and start again from there.

4 Continue working along the bottom line. Then start working from left to right along the next line up.

Note: If you accidentally press two keys together, you will see both keys displayed on the screen. You should press Break to continue.

If the same fault occurs repeatedly or the picture of the depressed key refuses to disappear, then it will be

IMPOSSIBLE to continue the test. You should replace the keyboard and start the whole test again.

40 Fault diagnosis

3000 Service Manual

5 When all keys in the main keyboard area have been pressed successfully, the screen clears and displays a diagram of the rest of the keyboard area. Again, press each key in turn, following the guidelines above.

6 When all the keys have been successfully pressed, the screen dears and displays the following message:

MOUSE TEST - PASSED

MAIN KEYBOARD TEST - PASSED

NUMERIC KEYPAD TEST - PASSED

PRESS RESET BUTTON TO END TEST

Press the RESET button on the side of the unit. You have now finished the keyboard functional test.

Action if tests fall

Make sure that the configuration items 'DELAY' and '

REPEAT are set to sensible values, such as Delay 32 and Data 4 — see the User Guide for details.

If the keyboard PCB is replaced, re-run the keyboard functional test.

Floppy disc drive

The Floppy disc drive test consists of two parts. The first part of the test checks the write protect mechanism. The test disc must be write protected for this test to work. If the A3000 disc drive passes, the following message is displayed:

FLOPPY DISC DRIVE TESTS

Checking write protect

PASSED Write Protect

Insert Scratch Disc

Then press SPACE

Replace the Test disc with an ADFS D format write enabled disc, the scratch disc. Any data already on this disc may be destroyed, so it is best to use a blank formatted disc.

The test continues with disc Read, Write and Erase tests. Each test gives a PASSED/FAILED message.

Action if test falls

If the test fails, check that the configuration for 'STEP' and 'FLOPPIES' is correct. Check the disc drive ID switch is set to the correct position — normally '0' for single floppy drive, '1' for second floppy drive.

Swap the cable and drive for known good examples.

Check power to to drive. If fault persists, change the main PCB.

RS 232

Ensure the A3000 RS232 test plug is fitted before carrying out this test (see the Appendix for details).

Action:

if the test fails, make sure that the configuration items '

BAUD' and 'DATA' are set to sensible values (Baud 4 and Data 4 for example). If the test still fails, after you have ensured that the loopback plug is functional on another unit, change the main PCB, or carry out the '

Serial socket' checks in the next chapter.

Printer

If one of the printer options was set, a test pattern is sent to the printer. The pattern comprises a repeated series of stepped lines each representing bits 0 to 7.

You should look for missing or corrupted pattern. As this is a subjective test, make a note of any faults that you detect.

Action If test fails

if the test fails with a known good printer and cable connected, check the configuration settings for '

PRINTER' and 'IGNORE' are correct. If the fault still persists, change the main PCB, or see the next chapter for repair information.

On completing the tests

On completing the tests the screen displays:

TESTS COMPLETE

TESTS COMPLETE

TESTS COMPLETE

TESTS COMPLETE

TESTS COMPLETE

TESTS COMPLETE and outputs a message to the printer. This indicates that the A3000 computer has passed all the nonsubjective tests. However, the message Tests

Complete should NOT necessarily be interpreted as a

PASS, since you may wish to fail the computer on one of the subjective tests.

If a failure has been found during the non-subjective tests, the screen displays a FAILED message and lists the failures on the printer, assuming that the printer is functioning and that you did not select the 'All Tests

Except Printers' option from the menu. Insert the Test

Disc and press 'space' to return to the main menu.

Fault diagnosis 41

3000 Service Manual

Upgrade tests

To test Upgrades fitted to the computer, follow the procedure detailed at the start of the 'Main functional test' section for loading and running the software, then select option 2 from the main Dealer Test Menu. The

Upgrades menu will appear:

A3000 Upgrades Test Menu

1 Midi

2 1M Byte Memory

3 RS232

4 Main Menu

SELECT OPTION:

Introduction

Type in the number of the test you wish to run; if it fails, substitute a known good upgrade. If the test still fails, replace the main PCB, or see the next chapter for repair information.

A3000 User Port MIDI Upgrade

Introduction

The UPM Upgrade functional test should be carried out whenever you install, repair or replace a UPM

Upgrade. The suite of programs provide assistance when fault finding, by providing continuous looping.

Note: The MIDI Thru' port is NOT tested.

Equipment required

In order to carry out the test, you will require the following equipment:

• UPM Upgrade to be tested, which should have been installed

• A3000 Computer

• 3.5 inch Test Disc, write protected

• Monochrome or analogue RGB monitor.

• Acorn Econet cable

• User port loopback plug (wired as in the diagram below)

• Dual trace oscilloscope, if you are fault finding.

Connecting the equipment

Connect the:

• Computer to the monitor

• MIDI IN socket to the MIDI OUT socket, using the

Econet cable

• User port loopback plug to the User port

• Monitor to the mains supply

• A3000 to the mains supply.

Running the test

When you have selected

Midi from the Upgrades menu, the UPM test menu will appear:

A3000 UPM UPGRADE DEALER TESTS

1Functional test.

2Functional test soak.

3Services routines.

Enter choice

Select the appropriate test from the menu; all tests load automatically.

Selections 1 and 2 give a PASSED or FAILED message.

Selections 3 gives a further choice, after which a

'

Running message indicates that the selected routine is functioning and the associated signals can be traced with an oscilloscope.

Action if test falls

Check that the test leads are working and are plugged into the correct sockets. if the test still fails then try using a known working PCB. If this passes then replace the

MIDI podule under test, or else replace the main PCB.

1 Mbyte DRAM Expansion Test

Selecting

1M Byte Memory from the Upgrades test menu runs the memory upgrade test, which records its progress on the screen:

1 Mbyte Dram Expansion Test

Phase one: incrementing pattern ....

Phase two: TRUE hierarchy ............

Phase three: FALSE hierarchy .........

Phase four: Cycling bits ............

PASSED/FAILED message

Press SPACE to continue.

42 Fault diagnosis

3000

Action if test falls

If the computer fails the test, restart the system with a delete-power-on and run the test again. If the test still fails, check the connection between the main PCB and the memory expansion card. If test fails yet again, try a known working memory card. If this fails, then replace the main PCB, else replace the faulty memory card.

RS 232 test

When it has been selected, this test will automatically run and give a PASSED or FAILED message.

Action

If the test fails, make sure that the configuration items '

BAUD' and 'DATA' are set to sensible values (BAUD 4 and DATA 4, for example). If the test still fails, after you have ensured that the loopback plug is functional on another unit, change the main PCB. A diagram for the loopback plug is included in the Appendices.

Service Manual

Fault diagnosis 4 3

3000 Service Manual

44 Fault diagnosis

3000

Main PCB fault diagnosis & repair

Service Manual

Introduction

This chapter deals with fault diagnosis and repair of the main PCB at component level.

See the previous chapter for basic fault diagnosis before proceeding to this chapter.

Tools required

The suggested tools for fault diagnosis and repair of the A3000 PCB are as follows:

• 100 MHz oscilloscope

• DC voltmeter

• Earth continuity tester (see Appendix B)

• Chip extraction tools (68/84 pin)

• Soldering/desoldering workstations, capable of handling both conventional and surface-mounted devices

• Standard handtools.

It is a recommended requirement that anti-static precautions should be utilised at all levels of servicing, ie antistatic matting and wrist-straps.

DANGER

AFTER REFITTING OR FITTING A

REPLACEMENT ASSEMBLY, CARRY OUT

EARTH CONTINUITY TESTING ON THE

ASSEMBLED COMPUTER ACCORDING TO THE

PROCEDURE GIVEN IN APPENDIX B.

WARNINGS

• Repairs to multi-layered PCBs:

The main PCB is a four-layer board.

Components should only be removed from the board using equipment specifically designed for this purpose. For details of suitable equipment available, contact Acorn Customer Service.

• Repairs to surface-mounted devices:

The ARM, MEMC, IOC AND VIDC ICs on the

A3000 PCB are surface-mounted components.

Do not attempt to remove them from the board and replace them unless you are appropriately trained in surface-mount technology and have the correct equipment to do so. f in doubt contact Acorn Customer Services.

• System clock failure: f the computer is powered on for more than a few seconds and there is no system clock, there is a risk that all four ARM chips may be damaged, as well as the RAM.

• Faulty MEMC: f MEMC is faulty or the RAS/CAS signals are not being generated, the RAM may be damaged if the machine is left on too long. If you suspect a fault in these areas, scope the RAS and CAS lines for a few seconds in order to make sure that they still active, then turn the machine off.

Do not leave the computer on for more than a few seconds at a time.

• Antistatic precautions:

It is a recommended requirement that anti-static precautions should be utilised at all levels of servicing, ie antistatic matting and wrist-straps.

Main PCB fault diagnosis & repair 45

3000 Service Manual

System failure

If the system appears to be dead, proceed as follows:

WARNING: System clock failure f the computer is powered on for more than a few seconds and there is no system dock, there is a risk that all four ARM chips may be damaged, as well as the RAM, due to lack of refresh on the

DRAM:

1 Check RAS and CAS on R133, R129-132.

2 Check IC41 pin 19 and IC37 pins 1 and 2 for clock signals.

3 Check for a RAS signal on pin 5 of all the

DRAMS.

1 Check for system RESET — look for a delayed signal on power on (on IC13 pin 29).

2 Check that the signal RST driving IC 44 pin 44 and IC

37 pin 9 is not stuck high.

3 Check for main system clock of 24 MHz on LK28. f absent, check again on IC47, pins 3, 4, 5 and 6, and change IC47 if required. Finally, change the crystal X3.

4 Check SKT 15 for the following: 27C to be CLK 2,

28C to be CLK 8 and 29C to be Ref 8.

5 Check for clocks on IC44 pin 67 and IC41 pin 19.

6 Check for the presence and validity of the processor addresses and PHI 1 clock. This can be done by examining the signals on IC 29 pins 12 to 19, IC 30 pins 12 to 19 and

IC 31 pins 12 to 15, whilst holding down the RESET button

(RESET can be activated by pressing the RESET key, or by short-circuiting SKT3 pin 15 and 16). When RESET is held down, the address lines will increment (not AO and Al)

. Should none of the signals toggle, check for the PHI 1 clock on the appropriate IC, at its source on IC 44 pin 66, and on R135. Also check to see that addresses are being presented to the inputs of the above devices. Change ICs

29, 30 or 31 as appropriate, or if no addresses are present, change the ARM — IC 37.

7 Check for all address lines on MEMC, 1C44, again with RESET held down.Check for the presence of LA2 to LA6 and LA16 to LA21 on 1OC IC13.

8 The data bus can be inspected by probing on resistors

R49 to R65, R115 to R128 and R87. Note that

MEMC1A will not enable the ROMs whilst RESET is activated. By their nature, it is difficult to interpret the signals seen, so just check for the ability of the signals to move between logic states. None of these lines should be stuck permanently high, low or in a midrail state. Any of these resistors may be removed in order to isolate the DRAM bank from the CPU, thus easing the tracing of shorts, etc. Also check for short or open circuits on the BDATA bus, IC 43 pins 12 to 19 and IC

46 pins 12 to 19.

9 Check for shorts on the DRAM address bus, either on the DRAMS themselves or on IC 44 pins 28 to 37.

Check all data signals on IC41.

10Check for Data and Address signals on all four of the

ROMs. This is especially important if a ROM change has been carried out, as misuse of a screwdriver during ROM removal may have damaged or broken PCB tracks, socket or ROM legs ( an IC extraction tool should have been used).

11 Check the processor interrupt lines FIO and IRO pins 8 and 7 on ARM IC 37. Neither of these should be stuck low. IRO can be expected to pulse low, FIO should be high. These interrupts should also be checked at their source on IOC IC13 pins 50 and 51. Should these also be low, the interrupt source can be traced by examining all interrupt inputs to IOC IC 13 on pins 30 to 42 (note that pins 30, 31 and 42 are active high logic).

46

Main PCB fault diagnosis & repair

3000 Service Manual

Test ROMs

The A3000 Test ROMs are designed to assist in the repair of all A3000 systems where 'Failure to Initialise' faults are present – ie the machine appears to be 'dead' on power-up.

The ROMs contain software which can be categorised in two sections:

1 Main memory test routines

2 Test routines for use under repetitive reset.

To install the test ROMs, carefully remove the RISC OS

ROM set, ICs 14, 15, 16 and 17, and replace them with the test ROMs, 1, 2, 3 and 4 respectively:

The test ROMs use the bare minimum of hardware to run the system – remove/disconnect all peripherals not needed for the tests, although a keyboard is needed. A printer can also be connected if required.

Main memory test

Providing that the ARM, MEMC and VIDC are functioning, the test ROMs will auto-boot into the menu-driven display below. At any point in the operation of the test ROMs, pressing the RESET key or re-powering the machine will re-start the program and re-display the menu:

0123456789012345678901234567890123456789012345678901234!

Al DIAGNOSTIC TEST ROMS MEMORY SIZE -&0XX00000 BYTES

1.

CYCLIC MEMORY TEST WITH PRINTOUT

2.

CYCLIC MEMORY TEST

SELECT: designated as 'screen memory'. f this occurs, the video display may become unreadable. For this reason, the sequence 0123456789 is repeated across the top line of the display. Every 4 digits represent a 32-bit word.

Watch for missing or corrupted display.

As the start of the screen memory is known to be at physical address &2000000, it should be possible to determine the exact device that is faulty by examining the corruption pattern on the display.

The default 'memory size' is &100000 bytes (1 Mbyte), however this may be cycled through 0.5, 1, 2 and 4

Mbyte memory sizes by pressing the 'M' key.

When using the ROMs on a machine having memory content other than 1 Mbyte, the video display may at first appear out of line or incorrect. In this instance press the M key repeatedly until the required memory size has been selected.

The memory test is cyclic and on completion of each full memory test a full stop (.) will be displayed until it completes one line of the screen. The next completed cycle will move the lefthand full stop down one pixel, and then in sequence across the screen. The 0.5

Mbyte test takes between 3 and 4 seconds to complete whilst the 4 Mbyte test takes about 29 seconds.

If for some reason the video display is completely blank or unreadable (eg because of a video fault), a printed output may be obtained by selecting option 1, the output being produced at the printer port as well as on the VDU.

If an error is found in the memory, the display will show:

AT ADDRESS &nnnnnnnn WROTE &pppppppp READ xxxxxxxxxxx

xxxxxxxxxxxxxxxxxxxxx

(The message will be displayed on one line) where nnnn is the faulty address, pppp is the data written to that address and

xxxxxxxx

is the data read back from that address in binary form. The least significant bit is the righthand bit.

The memory tests do not terminate unless an error is found, in which case after reporting 8 or 9 errors, the test will terminate. Any error will have a cascading effect, so it is good practice to repair the first error displayed first.

Note: An additional check is made on the state of

CMOS RAM control lines CO and C1 at the beginning of the test, before the display. If either of these lines are short-circuit to 0 Volts, the Test ROMs will indicate this on power-up.

The memory test checks memory according to memory size selected.

It is possible that faulty memory may lie in the region

Main PCB fault diagnosis & repair 47

3000 Service Manual

Memory map

Physical Address

&2000000

&2000001

&2000002

&2000003 repeat until

&20FFFFF

8 2100000 to

&21FFFFF

IC Numbers

IC21 IC20

IC22 IC23

IC24 IC25

IC26 IC27 upgrade

Repetitive reset test

This section of test code is intended for use when the main memory test menu fails to initialise.

To make use of this section of the ROMs the following test equipment is required:

• Oscilloscope

• Signal or pulse generator

The purpose of the code is to produce certain signals around specific areas of the PCB. These signals may then be monitored using the oscilloscope to assess the operation of that area of the circuit.

A suitable square wave or, preferably, a negative-going pulse generator output at 10 kHz should be connected to the reset line via a component connected to SKT3 pin

13.

After setting the border colour to white, the signals should be observable in the following order, which checks the output selection of IC13 (IOC):

SVPMD

SVPMD

SVPMD

OC CS & S1

OC CS & S2

OC CS & S3

OCCS&S4

OCCS&S5

OCCS&S6

OC CS & S7 nB/W nB/W nB/W

IOC CS & CO

IOC CS & C1

IOC CS & C2

10C CS & C3

IOC CS & C4h

IOC CS & C5

IOC CS low low low hi hi hi hi hi hi hi low low low hi hi hi hi hi hi hi

IC44 pin 52 and IC37 pin 10

IC13 pin 67 + pin 63

+ pin 62

+ pin 61

+ pin 59

+ pin 58

+ pin 57

+pin 56

IC44 pin 63 and IC37 pin 84

IC13 pin 67 + pin 44

+ pin 45

+ pin 46

+ pin 47

+ pin 48

+ pin 49

Repetitive reset test assembler listing

LDRT

LDRT

LDRT

LDR r0, r0, r0, r1,

[r5]

[1-5]

[r5] iocmof

48

LDRB

LDRB

LDRB

MOV

STR

MOV

STR

MOV

STR

MOV

STR

STR

MOV

STR

MOV

STR

MOV

LDR

LDR

LDR

LDR

LDR

LDR

LDR

LDR r0, r0, r0, r1 r1, r1 r1, r1 rl, r1 r1, r1, r1 r1, r1 r1, r1

1-0, r0, r0, r0, r0, r0, r0, r0,

[r1,r6]!

[r1, r6]!

[r1, r6]!

[r1, r6]!

[r1, r6]!

[r1, r6]!

[rl, r6]!

[r1, r6]!

[r5]

[r5]

[r5]

#&FE0000

[r7]

#&FD0000

[r7]

#&FB0000

[r7]

#&F70000

[r7]

#&EF0000

[r7]

#&DF0000

[r7]

#&FF0000

[r7]

;SVPMD pin low

;

;

)

)continual toggle of:-

)

;re—load ioc base addr. —offset

;SVPMD pin high

;IOC CS pin high

;IOC CS pin high

;IOC CS pin high

;IOC CS pin high

;IOC CS pin high

;IOC CS pin high

;IOC CS pin high

;nB/W pin high

;nB/W pin high

;nB/W pin high

;

; set C0

;

; set Cl

;

; set C2

;

; set C3

;

; set C4

;

; set C5

;

; reset all

;S1 ioc hi

;S2 ioc hi

;S3 ioc hi

;S4 ioc hi

;S5 ioc hi

;56 ioc hi

;S7 ioc hi

)

]

)

)

]

]

)

)

) I.O.C.

)

)

)

)

)

Main PCB fault diagnosis & repair

3000 Service Manual

Video faults

Video failure

1 Check for +5 V on both ends of L18. If open circuit then check C100 for a short circuit. Replace L18 and C100 as appropriate. Also check for 3.5 Volts (approx.) on IC

41 pin 43. Should this not be present then check R109,

D16 and C93.

2 Check for a 24 MHz clock on IC41 pin 19. f missing then check continuity to and through LK28 and R138.

3 Check for video data on IC41 pins 39, 40 and 41. f not present, check power supply to IC41.

4 Check for short circuits on signals VIDRQ and

VIDAK.

5 Check connection of all data lines to VIDC (IC41).

6 Finally, change IC41.

Unstable or scrolling display

The computer may have lost its configuration value for

SYNC. Type at the keyboard:

*

CON. SYNC 1 (RETURN)

Press reset RESET and see if if any change occurs.

Investigate configuration failure.

Check for CSYNC signal on SK14 pin 4. If not present, trace back through LK24, R535 and IC40, finally changing VIDC 1041.

Check settings of LK24 and LK27 (see Links table).

Corrupted display

If the display breaks up around its edges and spurious characters appear then investigate the system oscillator. Suspect IC47or X3.

Check DRAM using the memory test routines.

Colours incorrect or missing

With a full white screen, VIDC IC41 pins 39, 40 and 41 should all have the same signal on them. f not, check pin

43, which should show approximately 3.5V; if not, check

R109, C93 and D16. Finally, change VIDC, IC41.

Trace each signal through the periphery circuitry and out to SK14, where the voltage on R, G and B should be the same.

Audio

Test the audio with both headphones and internal speakers. Do not forget to issue *SPEAKER ON and

*VOLUME 127 commands, if required, making sure that the sound modules are active (see the 'No sound' algorithm in the previous chapter).

If either of the speakers fail, but the headphone socket functions normally, check connections to the main PCB via LK22 and LK23, and check IC32 or 1C38 pin 5 for a signal of 2-3 V amplitude. If no signal is present on pin 5 but can be found on pin 3, change IC32 or 38. Check continuity through R76 and R45 and check that IC13 pin

49 is not stuck high.

If there is no audio at all, first check for +5 V on both ends of L19.

f

this is open circuit, check the condition of

C108 before replacement. Check for about 3 V on

VIDC IC41 pin 12. f there is no voltage or a different one, check R500, C107 and C108.

A low amplitude signal should be found on VIDC IC41 pins 13, 14, 15 and 16. f not, change VIDC. These signals can be traced through the peripheral circuitry and out to 011 and 012. The signal amplitude at these points should be about 1.3 V pk-to-pk.

Check for short or open circuit on signals SNDAK and

SNDRQ on VIDC IC41 pins 9 and 24.

Configuration, NV memory and RTC

If the NVM suffers data retention problems and the RTC fails, then, with the computer power off, check for about

1.1 V on IC6 pin 8. If this voltage is not present, check

R3 and R7. If less then 1V, change the battery B1 and check the operation of D2 and C15.

If the NVM IC6 consistently fails on the same data bits, change the device.

If the clock fails to run or runs inaccurately, check and if necessary replace X2. LK7 allows access to the clock signal.

Main PCB fault diagnosis & repair 4 9

3000 Service Manual

Peripheral faults

Keyboard and mouse

Make sure that the configuration items DELAY and

REPEAT are set to sensible values - see the

A3000 User Guide.

Check computer interface by swapping to a known good keyboard or mouse.

Floppy disc drive

Make sure that the configuration items STEP and

FLOPPIES are correctly set. Check that the disc drive ID selection switch is in the zero position.

Swap the disc drive for a known good drive and cable. f this also fails, check the power supply connection for +5 V and 0 V.

If the computer is not recognising the drive, check that all cables are connected both to the drive and to the PCB, and that power is present on the power cable. Also check that the drive ID plate has not fallen off inside the drive and jammed it.

Printer

Make sure that the configuration items for IGNORE and PRINT are set to sensible values. Swap the printer for a known good printer and cable.

If the printer fails completely, check for a STROBE signal on Q1 collector; trace back through R36 and

IC18. Also check for shorts or open circuits on

PACK and PBSY on pins 2 and 4 of 1C9, and 11 and 13 of IC8.

If the data printed is incorrect, check the continuity of the data lines into and out of IC 11, though the series resistors and onto SK 10.

If both the printer and the floppy disc drive fail, change IC 18.

Capacitors C23 to C33 on the printer port occasionally go open circuit. These should be checked if printer problems are being experienced.

Serial port (upgrade)

Check that the upgrade has been correctly installed. Make sure that the configuration items

BAUD and DATA are set to sensible values. Check for =+10V on IC7 pin 1 and =-10V on pin 24.

Check for the clock on

IC 1 pins 6 and 7; change X1 if faulty. f OK, change IC1 and IC7.

Expansion cards

Run the relevant expansion card test; if it fails, substitute a known good expansion card. f the test still fails, check through System failure, tracing all signals through to the expansion card socket SK15 ( external) or SK3 and 11 (internal). f necessary, replace expansion card backplane.

WARNING

Power down the computer before fitting or removing an external expansion card.

50 Main PCB fault diagnosis & repair

3000

Parts lists

Service Manual

The parts lists in this chapter detail the components used in the manufacture of the computer and its upgrades. Contact the Spares Department of Acorn

Computers Limited (account holders only), or its authorised dealers and Approved Service Centres, for information as to which parts are available as spares.

Final assembly parts list

1

35

36

37

38

31

32

33

34

39

40

26

27

29

30

21

23

24

25

17

18

19

20

12

14

15

16

8

9

10

11

5

7

3

4

'per batch

Part no.

Description Qty

0060,000/A FINAL ASSEMBLY DRAWING 1*

0176.005

DISC DRIVE CABLE ASSY

0276,038 'NO ECONET' LABEL

0276,106 RESET BUTTON

0180,000 AVON MAIN PCB ASSY

0180.010

22W 240V PSU

0160,011 KEYBOARD (UK)

0180,012 MAINS CABLE ASSY

0180,081 SPEAKER ASSEMBLY

0183,004 3.5x1" 1MB DISC DRIVE

0260,061 LOWER MOULDING

0260.062

UPPER MOULDING

0260,063 BATTERY COVER

0280.073

BLANKING PANEL

0260,074 LOCK PLATE

0260,075 CABLE RESTRAINT PLATE

0260,077 PSU COVER

0280,078 PSU INSULATION SHEET

0480,041 BBC/LED LABEL

0480,042 BASE LABEL

0480.043

'NO SERIAL' LABEL

0480,044 REAR MAINS LABEL

0480,047 ACORN LOGO LABEL

0860,024 GMAT CBL RND 7,4Dx4T BLK

0940,007 ADH HOT-MELT

0882,770 SCW No2x1/4" PLST PAN POS

0882.716

SCW No4x1/4" PLST PAN POS

0662,111 SCW M2.5x6 PAN HD POSI

0662,121 SCW M3x6 PAN HD POSI

0862,711 SCW No4x3/4" PLST PAN POS

0682,730 SCW No6x3/8" PLST PAN POS

0882,971 WSHR M2,5 SPRF IT STL 2

0884,048 RIVET PLST DOME 3,1Dx4THK 1

1

1

4

4

1

2

0691,026 LABEL HiVOLT40mmSq MAX SA 1

0890,013 FOOT S/A RUBR 8Dx2.5Hmm

2

1

1

1

1

1

1

1

A/R

1

1

1

2

1

1

1

1

1

2

1

1

1

1

1

1

PCB assembly parts list

10

11

12

13

15

17

19

1

6

9

2

3

Item Part no.

Description Qty

0260,000 BARE PCB 1

0160.000/A AVON PCB ASSEMBLY DWG 1*

0180,000/C AVON PCB CIRCUIT DIAGRAM 1*

0280,072 PCB BACK PANEL

0800,070 CONR 2W SHUNT 0.1"

1

10

(FITTED TO LK17-20,24-29)

0800,126 SKT IC 24/0.3" NORM (IC7)

0800,128 SKT IC 28/0.6" NORM (IC1)

0600,132 SKT IC 32/0.6" SUPA (IC14-17) 4

1

1

11C2 0800,140 SKT IC 40/0.6" NORM

0870,422 WIRE 25SWG CPR TIN A/R

(X1,X2,X3)

0902,004 LABEL SERIAL PCB 15x50mm 1 xxxx,xxx RIVET AVDEL 11070312 (SKIS) 2

R1

R66

R67-

R71

R72-

R75

R76

R77

R76

R43

R44

R45

R46

R47

R48

R49-

R65

R79

R80

R61

R82

R83

R84

R85

R86

R87

R35

R36

R37

R36

R39

R40

R41

R42

R25-

R28

R29

R30

R31

R32

R33

R34

R10

R11

R12

R13

R14

R15

R16-

R24

R2

R3

R4

R5

R6

R7

R6

R9

0521,102 RES 1K0 SW 5% 0W25 1206 1

0521.102

RES 1 K0 SMD 5% 0W25 1206

0521,181 RES 160R SMD 5%0W25 1206

0521,331 RES 330R SMD 5% 0W25 1206 1

0521,271 RES 270R SMD 5% 0W25 1206 1

1

1

0521,181 RES 160R SMD 5%0W25 1206

0521.101

RES 100R SMD 5% 0W25 1206 1

N/F

1

0521223 RES 22K SMD 5% 0W25 1206

0521,472 RES 4K7 SMD 5% 0W25 1206

0521,102 RES 1 K0 SMD 5% 0W25 1206

0521,472 RES 4K7 SMD 5% 0W25 1206

0521,472 RES 4K7 SW 5%0W25 1206 1

0521,331 RES 330R SMD 5% 0W25 1206 1

0521,222 RES 2K2 SMD 5% 0W25 1206 1

1

1

1

1

0521,220 RES 22R SW 5% 0W25 1206 9

0521,472 RES 4K7 SW 5%0W25 1206

0521,102 RES 1K0 SW 5% 0W25 1206

0521,472 RES 4K7 SMD 5% 0W25 1206

0521,472 RES 4K7 SMD 5% 0W25 1206

0521,103 RES 10K SMD 5% 0W25 1206

0521,103 RES 10K SMD 5% 0W25 1206

0521,331 RES 330R SW) 5% 0W25 1206

0521,331 RES 330R SW) 5% 0W25 1206

0521,102 RES 1K0 SW 5% 0W25 1206 1

0521,104 RES 100K SMD 5% 0W25 1206 1

0521,104 RES 100K SMD 5% 0W25 1206 1

0521,104 RES 100K SMD 5% 0W25 1206 1

0521,103 RES 10K SMD 5% 0W25 1206 1

0521,104 RES 100K SMD 5% 0W25 1206 1

0521,104 RES 100K SMD 5% 0W25 1206 1

0521,102 RES 1K0 SMD 5% 0W25 1206

0521,472 RES 4K7 SMD 5% 0W25 1206

0521,562 RES 5K6 SMD 5% 0W25 1206

0521,681 RES 680R SW 5%0W25 1206

0521,100 RES 10R SW 5% 0W25 1206

0521,122 RES 1K2 SMD 5% 0W25 1206

1

1

1

1

1

1

4

1

1

1

1

1

1

1

0521,680 RES 66R SMD 5% 0W25 1206 17

0521,331 RES 330R SMD 5% 0W25 1206 1

0521,220 RES 22R SMD 5% 0W25 1206 5

0521,472 RES 4K7 SMD 5% 0W25 1206

0521,562 RES 5K6 SW 5% 0W25 1206

0521,681 RES 660R SMD 5% 0W25 1206 1

0521,100 RES 10R SMD 5% 0W25 1206

4

1

0506,250

0521,330

0521,332

0507,223

0506250

0521.560

0521,332

0507,223

0521,680

RES 332R MF 1%0W25 E96

RES 33R SMD 5% 0W25 1206

RES 3K3 SMD 5%0W25 1206

RES 22K MF 1% 0W25

RES 332R ME 1% 0W25 E96

RES 56R SMD 5% 0W25 1206

RES 3K3 SMD 5% 0W25 1206

RES 22K MF 1% 0W25

RES 68R SMD 5% 0W25 1206

1

1

1

1

1

1

1

1

1

1

Main PCB fault diagnosis & repair 51

3000 Service Manual

Item Part no. Description Qty

R88

P531

R532

R533

R534

R535

R536

R537

R538

R539

R540

R541

P542

R543-

R546

R547

R548

R138

R139

R140

R141

R142

R143

R144

R145

R500

R501

R502

R503-

R518

R519-

R529

R530

R549

R550

R551

R552

R553

P554

R555

R556

P557

R558

R559

R560

R561

R105

R106

R107

R108

R109

R110-

R115

R114

R115-

R128

R129-

R133

R134

R135

R136

R137

R89

R90

R91

R92

R93

R94

R95

R96

R97

R96

R99

R100

R101

R102

R103

R104

0521,332 RES 3K3 SMD 5% 0W25 1206 1

0521,332 RES 3K3 SMD 5% 0W25 1206

0521,560 RES 56R SMD 5% 0W25 1206

0507,223 RES 22K MF 1% 0W25

0521,332 RES 3K3 SMD 5% 0W25 1206

0507,223 RES 22K MF 1% 0W25

0521,560 RES 56R SMD 5% 0W25 1206

0507,223 RES 22K MF 1% 0W25

0506,250 RES 332R MF 1% 0W25 E96

0507,223 RES 22K MF 1% 0W25

0507,223 RES 22K MF 1% 0W25

0507,223 RES 22K MF 1% 0W25

0521,330 RES 33R SMD 5% 0W25 1206

0521,332 RES 3K3 SMD 5% 0W25 1206

0506,161 RES 43R2 MF 1% 0W25 E96

0506,161 RES 43R2 MF 1% 0W25 E96

0506,161 RES 43R2 MF 1% 0W25 E96

0521,681 RES 680R SW 5%0W25 1206

0521,103 RES 10K SMD 5%0W25 1206

0521,103 RES 10K SMD 5% 0W25 1206 1

0521,331 RES 330R SMD 5% 0W25 1206 1

0521,103 RES 10K SMD 5% 0W25 1206

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

0506,300 RES 1K00 MF 1% 0W25 E96

0521,122 RES 1K2 SMD 5% 0W25 1206

0521,680 RES 68R SMD 5% 0W25 1206

0521,220 RES 22R SMD 5% 0W25 1206

0521,122 RES 1K2 SMD 5% 0W25 1206

0521,330 RES 33R SMD 5% 0W25 1206 1

0521,221 RES 220R SMD 5% 0W25 1206 1

5

1

0521,103 RES 10K SMD 5% 0W25 1206

0521,680 RES 68R SMD 5% 0W25 1206

0521,680 RES 68R SMD 5% 0W25 1206

0521,680 RES 68R SMD 5% 0W25 1206

0521,220 RES 22R SMD 5% 0W25 1206

0521,220 RES 22R SMD 5% 0W25 1206

0521,220 RES 22R SMD 5% 0W25 1206

0521,103 RES 10K SMD 5% 0W25 1206

0521,472 RES 4K7 SMD 5% 0W25 1206

0521,333 RES 33K SWD 5% 0W25 1206

0521,103 RES 10K SMD 5% 0W25 1206

0521,472 RES 4K7 SMD 5% 0W25 1206

1

1

1

1

1

1

1

1

1

1

1

1

4

1

14

0521,680 RES 68R SMD 5% 0W25 1206 16

0521,104 RES 100K SMD 5%0W25 1206

0521,102 RES 1K0 SMD 5% 0W25 1206

0521,181 RES 180R SMD 5%0W25 1206

0521,820 RES 82R SMD 5% 0W25 1206

0521,331 RES 330R SMD 5% 0W25 1206 1

0521,680 RES 68R SMD 5% 0W25 1206 1

1

1

1

11

1

0521,680 RES 68R SMD 5% 0W25 1206

0521221 RES 220R WO 5% 0W25 1206

0521,680 RES 68R SMD 5% 0W25 1206

0521,221 RES 220R SMD 5% 0W25 1206 1

1

1

0521,680 RES 68R SMD 5% 0W25 1206 1

0521,221 RES 220R SMD 5% 0W25 1206 1

0521,680 RES 68R SW) 5% 0W25 1206 1

0521,221 RES 220R SMD 5% 0W25 1206 1

0521,102 RES 1 K0 SMD 5% 0W25 1206

0521,472 RES 4K7 SMD 5% 0W25 1206

0521,472 RES 4K7 SMD 5% 0W25 1206 1

0521,104 RES 100K SMD 5% 0W25 1206 1

4

1

0521,472 RES 4K7 SMD 5% 0W25 1206

0521,472 RES 4K7 SMD 5% 0W25 1206

0521,472 RES 4K7 SMD 5% 0W25 1206 1

0521221 RES 220R SMD 5% 0W25 1206 1

0521,103 RES 10K SMD 5% 0W25 1206

1

1

0521,473 RES 47K SMD 5% 0W25 1206

0521,331 RES 330R SMD 5% 0W25 1206 1

0521,271 RES 270R SW 5% 0W25 1206 1

1

N/F

N/F

1

N/F

N/F

52

C75

C76

C77

C78

C79

C80

C81

C82

C83

C67

C68

C69

C70

C71

C72

C73

C74

C59

C60

C61

C62

C63

C64

C65

C66

C48

C49

C50-

054

C55

C56

C57

C58

C34

C35

C36

C37

C38

C39

C40-

C47

C20

C21

C22

C23

C24-

C31

C32

C33

C12

C13

C14

C15

C16

C17

C18

C19

CI

C2

C3

C4

C5

C6-

C10

C11

C84

Item

R562

R563

R564

R565

R566

R567-

R571

R572

R573-

R579

Part no. Description Qty

0521,473 RES 47K SW 5% 0W25 1206

0521,473 RES 47K SMD 5% 0W25 1206

N/F

N/F

1

0521,473 RES 47K SMD 5% 0W25 1206

0521,221 RES 220R SMD 5% 0W25 1206 1

N/F

5

N/F

0681,001 PCPCTR DCPLR 33n SMD 1210 1

0631.033 CPCTR CPLT 33p 30V 2%

0640,473 CPCTR CER 47n 30V 80%

0610,010 CPCTR TANT 10u 10V 20%

0681,001 CPCTR DCPLR 33n SMD 1210

1

1

1

1

0635,100 CPCTR ALEC 10u 16V RAD

0681,001 CPCTR DCPLR 33n SMD 1210

0635230 CPCTR ALEC 220u 16V RAD

0610,010 CPCTR TANT 10u 10V 20%

0635,230 CPCTR ALEC 220u 16V RAD

0635,470 CPCTR ALEC 47u 16V RAD

0631,012 CPCTR CPLT 12p 30V 2%

0681,001 CPCTR DCPLR 33n SMD 1210

0681,001 CPCTR DCPLR 33n SMD 1210

0635,100 CPCTR ALEC 10u 16V RAD

0681,001 CPCTR DCPLR 33n SMD 1210

0681,001 CPCTR DCPLR 33n SMD 1210

0610,010 CPCTR TANT 10u 10V 20%

0631,100 CPCTR CPLT 100p 30V 2%

1

1

1

1

1

1

1

1

1

1

1

1

5

1

0630,220 CPCTR CPLT 2n2 30V 10%

0631,100 CPCTR CPLT 100p 30V 2%

0631,100 CPCTR CPLT 100p 30V 2%

0610,010 CPCTR TANT 10u 10V 20%

0681,001 CPCTR DCPLR 33n SMD 1210

0681,001 CPCTR DCPLR 33n SMD 1210

0681,001 CPCTR DCPLR 33n SMD 1210

0621,470 CPCTR ALEC 47u 10V AX

0681,001 CPCTR DCPLR 33n SMD 1210 8

0681,003 CPCTR DCPLR 100n SMD 1210 1

0681,003 CPCTR DCPLR 100n SMD 1210 1

1

1

8

1

1

1

1

N/F

1

0681,001 CPCTR DCPLR 33n SMD 1210

0610,010 CPCTR TANT 10u 10V 20%

0681,003 CPCTR DCPLR 100n SMD 1210 1

0610,010 CPCTR TANT 10u 10V 20%

5

1

1

0681,003 CPCTR DCPLR 100n SMD 1210 1

0681,001 CPCTR DCPLR 33n SMD 1210

0635,470 CPCTR ALEC 47u 16V RAD

0635,230 CPCTR ALEC 220u 16V RAD

0640,473 CPCTR CER 47n 30V 80%

0635,470 CPCTR ALEC 47u 16V RAD

0681,001 CPCTR DCPLR 33n SMD 1210

0642,103 CPCTR ALEC 100u 25V RAD

0635,230 CPCTR ALEC 220u 16V RAD

0635,047 CPCTR ALEC 4u7 16V RAD

0640,473 CPCTR CER 47n 30V 80%

0635,230 CPCTR ALEC 220u 16V RAD

0642,103 CPCTR ALEC 100u 25V RAD

0681,003 CPCTR DCPLR 100n SMD 1210 1

0681,003 CPCTR DCPLR 100n SMD 1210 1

1

1

1

1

1

1

1

1

1

1

1

1

0681,003 CPCTR DCPLR 100n SMD 1210 1

0640,473 CPCTR CER 47n 30V 80%

0630,220 CPCTR CPLT 2n2 30V 10%

0681,001 CPCTR DCPLR 33n SMD 1210

0650223 CPCTR MPSTR 22n 50V 10%

0610,010 CPCTR TANT 10u 10V 20%

1

1

0630,100 CPCTR CPLT 1n 30V 10%

0650,106 CPCTR MPSTR 100n 50V 10%

0630,220 CPCTR CPLT 2n2 30V 10%

0630,220 CPCTR CPLT 2n2 30V 10%

0621,470 CPCTR ALEC 47u 10V AX

1

1

1

1

1

1

1

1

0681,003 CPCTR DCPLR 100n SMD 1210 1

Main PCB fault diagnosis & repair

3000

Item Part no. Description Qty

C85 0630,100 CPCTR CPLT 1n 30V 10% 1

C86

C87

C88

C89

C90

C91

C92

C93

C94

C95

C96

C97

0630,220 CPCTR CPLT 2n2 30V 10%

0681,001 CPCTR DCPLR 33n SW) 1210

0650,106 CPCTR MPSTR 100n 50V 10% 1

0610,010 CPCTR TANT 10u 10V 20%

0630,220 CPCTR CPLT 2n2 30V 10%

0630,220 CPCTR CPLT 2n2 30V 10%

0650,223 CPCTR MPSTR 22n 50V 10%

0635,100 CPCTR ALEC 10u 16V RAD

0610,010 CPCTR TANT 10u 10V 20%

0635,470 CPCTR ALEC 47u 16V RAD

0640,473 CPCTR CER 47n 30V 80%

0635,100 CPCTR ALEC 10u 16V RAD

C98

C99

0681,001 CPCTR DCPLR 33n SW) 1210

0681,001 CPCTR DCPLR 33n SW) 1210

C100 0610,010 CPCTR TANT 10u 10V 20%

C101

1

1

1

1

1

1

1

1

1

1

1

1

1

1

C102

C103

C104

C105 0681,001 CPCTR DCPLR 33n SMD 1210 1

N/F

N/F

N/F

N/F

C106 0681,001 CPCTR DCPLR 33n SW) 1210

C107 0640,473 CPCTR CER 47n 30V 80%

C108 0610,010 CPCTR TANT 10u 10V 20%

C109 0621,470 CPCTR ALEC 47u 10V AX

C110 0621,470 CPCTR ALEC 47u 10V AX

C111 0610,010 CPCTR TANT l0u 10V 20%

C112 0635,230 CPCTR ALEC 220u 16V RAD 1

C113 0681,001 CPCTR DCPLR 33n SMD 1210 1

1

1

1

1

1

1

C114 0631,010 CPCTR CPLT 10p 30V 2%

C115 0631,033 CPCTR CPLT 33p 30V 2%

C116 0630,270 CPCTR CPLT 2n7 30V 10%

C500-

0506 0681,001 CPCTR DCPLR 33n SMD 1210 7

1

1

1

IC1

IC10

IC11

IC12

IC13

IC14

IC15

IC16

IC17

IC2

IC3

IC4

ICS

IC6

IC7

IC8

IC9

0280,022 IC KBD CNTRLR (0708,051)

0740,038 IC 7438 TTL 14/0.3"

0742,145 IC 74LS145 TTL 16/0.3

0742,145 IC 74LS145 TTL 16/0.3

0708,583 IC 8583 RTC RAM 8/0.3"

0749,014 IC 74HCT14 CMOS 14/0.3"

0747,004 IC 74HC04 CMOS 14/0.3"

0747,074 IC 74HC74 CMOS 14/0.3"

0742,374 IC 74LS374 TTL 20/0.3'

0747,138 IC 74HC138 CMOS 16/0.3"

2201,368 IC 10C (PLSTC)

0283.022 RISC OS ROM 1 V2.0

0283,023 RISC OS ROM 2 V2.0

0283,024 RISC OS ROM 3 V2.0

0283,025 RISC OS ROM 4 V2.0

0747,574 IC 74HC574 CMOS 20.0.3"

0747,574 IC 74HC574 CMOS 20.0.3"

IC18

IC19

IC20-

IC27

IC28

IC29

IC30

IC31

0704,118 IC DRAM 256Kx4 120n 20ZIP

0747,139 IC 741HC139 CMOS 16/0.3"

0747,573 IC 74HC573 CMOS 20/0.3"

0747,573 IC 74HC573 CMOS 20/0.3"

0747,573 IC 74HC573 CMOS 20/0.3"

1C32 0770,386 IC LM386 AUDIO AMP

IC33

IC34

IC35

IC36

IC37

IC38

IC39

IC42

IC43

IC44

IC45

IC46

IC47

0747,139 IC 74HC139 CMOS 16/0.3"

0747,000 IC 74HC00 CMOS 14/0.3"

0740,006 IC 7406 TTL 14/0.3"

0740,016 IC 7416 TTL 14/0.3" (OPTION)

0701,772 IC 1772 FDC 28/0.6'

2201,365 IC ARM Rum PLSTC)

0770,386 IC LM386 AUDIO AMP

0770,324 IC LM324 QUAD OP AMP

1C40 0750,086 IC 74AC86 CMOS 14/0.3"

IC41 2201,367 IC VIDC 1A (PLSTC)

0749,573 IC 74HCT573 CMOS 20/0.3"

0747,573 IC 74HC573 CMOS 20/0.3"

2201,375 IC MEMC 1 A {PLSTC-8MHz)

0749,573 IC 74HCT573 CMOS 20/0.3'

0747,573 IC 74HC573 CMOS 20/0.3"

0747,004 IC 74HC04 CMOS 14/0.3"

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

8

1

N/F

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

N/F

Service Manual

Item Part no.

Description

01

02-

010

011

012

D1

02

D3-

D16

B1

0780,241

0794,005 DIODE SI 1N4005 600V 1A

0794,148 DIODE SI 1N4148

BAT NICAD 1V2 280mAH PCB

0817,013

TRANS 8C239 NPN 0.2"P LDS

0783,907 TRANS 2N3906 PNP .2"P LDS

0780,241 TRANS BC239 NPN 0.2"P LDS

0780,241 TRANS BC239 NPN 0.2-P LDS

Qty

1

9

1

1

N/F

1

14

1

L1-

L14

L15

L16

L17

L18

L19

L20

L21

(0500,000 RES ZERO-OHM 0W25 (0.6"ptch) 14

(0870,420 WIRE 22SWG TIN (OPTION)

0860,015

0860,015

0860,012

0860,005

0860,015

0860,015

CHOKE RF FE BEAD

CHOKE RF FE BEAD

CHOKE RF 2u2H AX 0-30

COIL RF 33uH AX 0-45

CHOKE RF FE BEAD

CHOKE RF FE BEAD

LK 1-

LK16

LK17 0800,050 CONR 2W WAFR 0.1" ST PCB

LK18 0800,050 CONR 2W WAFR 0.1" ST PCB

11(19 0800,051 CONR 3W WAFR 0.1" ST PCB

LK20 0800,051 CONR 3W WAFR 0.1' ST PCB

LK21

LK22 0800,458 CONR 2W WAFR 0.1" ST LK

LK23 0800,458 CONR 2W WAFR 0.1" ST LK

LK24 0800,051 CONR 3W WAFR 0.1" ST PCB

LK25 0800,050 CONR 2W WAFR 0.1" ST PCB

1K26 0800.050

CONR 2W WAFR 0.1" ST PCB

LK27 0800,050 CONR 2W WAFR 0.1" ST PCB

LK28 0800,050 CONR 2W WAFR 0.1" ST PCB

LK29 0800,050 CONR 2W WAFR 0.1" ST PCB

LK30 0800,050 CONR 2W WAFR 0.1" ST PCB

LK31 0800,050 CONR 2W WAFR 0.1" ST PCB

1

1

1

1

N/F

1

1

1

1

1

1

1

1

1

1

1

N/F

1

2

2

1

N/F

1

PL 1

PL2

0180,013 EARTH STRAP {PCB/PSU} 1

0800,291 CONRD 9W PLG RAPCB+RFI+LK 1

PL3

PL4

PL5

0800.203

FSTN TAB 6,3mmx0,8 ST PCB

0800,203 FSTN TAB 6,3mmx0,8 ST PCB

1

1

N/F

PL6 0803,102 CONR 34W BOX IDC LP ST 1

SKI 0800,920 CONR 9W MINDIN RA PCB 1

SK2

SK3

SK4

SK5

SK6

SK7

SK8

SK9

0800,004 CONR SW SKT DIN RA PCB

0800,487 CONR 17W SKT 0.1" PCB

0800,487 CONR 17W SKI' 0.1" PCB 1

0800,481 CONR 5W SKT HSNG 0.1" PCB 1

1

1

0801,202

0801,202

0800,486

0800.486

CONR 20W 0.1" FLXPCB SKT

CONR 20W 0.1" FLXPCB SKT

CONR 5W SKT 0.1" PCB

CONR 5W SKT 0.1" PCB

SK10 0800,293 CONRD 25W SKT RAPCB+RFI+L 1

SK11 0800,487 CONR 17W SKT 0.1" PCB 1

SK12 0800,642 CONR JKSKT 3W 3,5mm RAPCB 1

SK13 0800,611 CONR PHONO SKT RA PCB 1

SK14 0800,292 CONRD 9W SKT RAPCB+RFI+LK 1

SKIS 0800,411 CONR 64W SKT RA AC PCB 1

SK16 0800,476 CONR 20W WAFR 0.1 ST 10mm 3

1

1

1

1

SW1 0805,704 SW 2P MOM CO P/B RA PCB

X1

X2

X3

0820,019

0821,327

0820240

XTAL 1.8432MHz HC18

XTAL 32.768KHz CC 0.05'

XTAL 24.00MHz HC18

1

1

1

1

Main PCB fault diagnosis & repair 53

3000

2Mb RAM upgrade

Item

1

2

3

C 1-

C8

C9

C10

IC1-

1C8

SK1

SK2

SK3

Part no.

Description

0280,200 BARE PCB

0180,200/A ASSEMBLY DRAWING

0180,200/C CIRCUIT DIAGRAM

0680,102

0635,470

0635,470

CPCTR DCPLR 100n AXA 25V

CPCTR 47u ALEC 16V RAD

CPCTR 47u ALEC 16V RAD

0704,118 IC DRAM 256Kx4 120n 20ZIP

0800,488

0800,488

0800,488

CONR 20W SKT 0 . r RA PCB

CONR 20W SKT 0.1" RA PCB

CONR 20W SKT 0.1" RA PCB

8

1

1 thy

1

1*

1*

8

1

1

1

•per batch

Service Manual

User Port MIDI upgrade

L1 -

L18

R1

R2

R3

R

4

R5

R6

R7

R8

R9

RI0

R11

R12

C1

C2-

C8

IC 1

IC2

IC3

IC4

ICS

IC6

D1

Item

2

3

6

9

11

Part no.

Description

0180,300/A ASSEMBLY DRAWING

0180,300/C CIRCUIT DIAGRAM

0280,360

0800,128

0884,042

PCB REAR PANEL

SKT IC 28/0.6" NORM

RIVET POP DOME 3,2D & THK

(USE ON ITEM 6)

0500,000 RES

ZE

RO R 0W25

0502.222

0502222

0502,221

0502,221

0502,221

0502,221

0502,102

0502,222

0502,222

0502,221

0502,103

0502,103

RES 21(2 C/MF 5% 0W25

RES 21(2 C/MF 5% 0W25

RES 220R C/MF 5% 0W25

RES 220R C/MF 5% 0W25

RES 220R C/MF 5% 0W25

RES 220R C/MF 5% 0W25

RES 1K0 C/MF 5% 0W25

RES 2K2 C/MF 5% 0W25

RES 2K2 C/MF 5% 0W25

RES 220R C/MF 5% 0W25

RES 10K C/MF 5%0W25

RES 10K C/MF 5%0W25

0635,230

0680,002

CPCTR 220u ALEC 16V RAD

CPCTR DCPLR 33/47n 0.2"

0706,525

0799,504

0280,320

0740,006

0732,691

0747,139

IC 65C22 VIA CMOS 2MHz

OPTO ISOL 6N138 8/0.3"

ROM (0727,128/9 TBP)

IC 7406 TTL 14/0.3"

IC 2691 UART CMOS 24/0.3"

IC 74HC139 CMOS 16/0.3"

0794,148 DIODE 1N4148 SI

LK 1-

LK4

SK1

SK2

SK3

SK4

SK5

SK6

0800,009

0800,004

0800,004

0800,004

0800,475

0800,475

CONR 20W HDR IDC RA 4WALL

CONR SW SKT DIN RA PCB

CONR 5W SKT DIN RA PCB

CONR 5W SKT DIN RA PCB

CONR 17W WAFR 0.1 23,5mmL

CONR 17W WAFR 0.1 23,5mmL

Qty

1 "

1*

1

11C3

2

1

1

1

1

1

1

1

1

7

18

1

1

1

1

1

1

1

1

1

1

1

1

N/F

1

1

1

1

1

1

• per batch

54 Main PCB fault diagnosis & repair

3000 Service Manual

Appendix A: Serial port loopback plug

Serial port loopback plug

Parts list*

Item

1

3

5

R1

R2

R3

R4

R5

R6

R7

R8

D1

D1

Part no.

Description

0276.081

CIRCUIT 8 ASSEMBLY DRAWING

0800,288 CONR 9W SCKT 'D' ST MS SB

0800,991 CONR 9W SHELL D' + SCREWS

0502,122 RES 1K2 C/MF 5% 0W25

0502,122 RES 1K2 C/MF 5% 0W25

0502,122 RES 1K2 C/MF 5%0W25

0502,122 RES 1K2 C/MF 5% 0W25

0502,472 RES 4K7 C/MF 5% 0W25

0502,472 RES 4K7 C/MF 5% 0W25

0502,472 RES 4K7 C/MF 5% 0W25

0790,085 DIODE BAT85 SBL

0790,085 DIODE BAT85 SBL

Qty

1

1

1'

1

1

1

1

1

1

1

N/F

1

1

per batch

Assembly notes

Assemble the components onto 'Veroboard', and fit item

5 (the shell) to protect the assembly

Main PCB fault diagnosis & repair 55

3000 Service Manual

56 Main PCB fault diagnosis & repair

3000 Service Manual

Appendix B: Earth continuity testing

Equipment required

An earth continuity tester capable of sourcing 25A derived from an AC source with a no-load voltage not exceeding 12V.

It is recommended that the calibration and operation of the instrument be checked frequently enough to assure its accuracy.

Test Procedure

DANGER

THE FOLLOWING TESTS INVOLVE HIGH

CURRENTS BUT LOW VOLTAGES. ALL

NECESSARY PRECAUTIONS MUST BE TAKEN

TO ENSURE OPERATOR SAFETY DURING

TESTING.

DANGER

SWITCH OFF THE COMPUTER, DISCONNECT IT

FROM THE MAINS SUPPLY, AND DISCONNECT

ANY PERIPHERALS BEFORE CARRYING OUT

THIS TEST.

The test should be performed on a fully assembled computer.

Using the Earth continuity tester, check the continuity between the power supply cord 13A plug earth pin and the following points:-

1 the rear panel internal expansion card fixing screws

2 both printer/parallel port D-type fixing bolts.

The resistance measured between the earth pin and each of the above test points shall not exceed 0.15 a

This value includes an allowance for the resistance of the mains cable. The duration of each test shall not exceed 10 seconds. No waiting period between tests is necessary.

Main PCB fault diagnosis & repair 5 7

Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement