UQD 34 - quad
UAD 34
service data
Quad Electroacoustics Ltd.
30, St Peters Road, Huntingdon, Cambs, PE18 7DB, England.
Telephone: 0480 52561 Telex: 32348 QUAD G
QUAD 34 service data
Contents Page
Introduction... LL LL LL LL A LL A LA A LA Ra A a LL LL 4
Circuit Description Power Supply............. aaron 4
Clamp Circuit ..... 2... eee. 4
Switching.. 00000002 4
Tone Controls... ... 2... eee, 6
Filters 2... 0r0reooeaa aa. 9
Fault Finding Diagnoses. . .... o. 00,0. 11
Flow Diagram. ........... 0... 13
Test Procedure. . ... ee00e0u0anaoco nea ve en 14
Modifications . . . oo edad e0 een ueaenro aa. 21
Complete Parts List ............. 2... 0000000000000. 22
Assembly Diagram. ......... 2.2000. 000di nar avee re re 30
Circuit Diagram 1 Up to Serial Number 6000 ..................... 31
Circuit Diagram 2 From Serial Number 6001 to 8000 .............. 32
Circuit Diagram 3 From Serial Number 8001... ................... 33
QUAD 34 service data
introduction
The Quad 34 control unit has inputs for pickup, tape recorder, radio tuner and compact disc player. The latter can
also be used for a second radio tuner or for record/replay with a two head cassette recorder. The chosen input is
selected by pushbuttons and amplified to power amplifier input level. Filter, Tilt and Bass controls enable the listener
to correct for certain room effects and programme balance.
circuit description
- POWER SUPPLY
Transformer secondary volts are approximately 27V depending on the value of the AC supply volts. This is rectified
and smoothed, and the resulting 30V DC is applied to the input of a negative voltage regulator. The output from the
regulator is —18V referenced to the positive rail for input voltages of =21V to —33V.
1C23 is connected as an earthed feedback buffer and is used in conjunction with R123 and R124 to convert the
regulator output to a +ve and —ve rail. The values of the rails are determined by the values of R123 and R124. Any
fluctuation in the voltage at pin 3 of 1C23 will cause the Op Amp to pass current through pin 3 and the appropriate
HT rail to offset the original change. C58 and C84 decouple the HT rails. R84, D30 and R85 define the +7.5V and
—7.5V supply rails necessary to drive the CMOS circuits, with Cb7 and Cb9 decoupling these points.
CLAMP CIRCUIT
Immediately after switch on of the 34 the regulator will be in the voltage drop-out mode since there are insufficient
input volts. Under these conditions there will be a 1.1V drop between the regulator output and input. This is applied
via the differentiator of R102 and C69 to the base of T13 which will remain firmly off. Point A (see circuit diagram)
will be +ve with respect to earth, hence the clamp transistors T14 and T15 will be turned on short circuiting the
audio output to earth.
When the voltage applied to the input of the regulator is sufficient to operate the regulator further increase in input
will give no change in output increasing the voltage applied to the differentiator. C69 will continue to charge via
R102, allowing time for the HT rails to stabilise before switching on T13. When T13 turns on, the voltage at point A
will drop and the clamp transistors will be turned off. The value of reversed bias applied to the base emitter junctions
of the clamp transistors will vary according to the AC supply voltage however D32 ensures that the value never
exceeds approximately 4V.
Note: The difference between regulator input and output voltage must be approximately equal to 2V before T13 will
turn on hence turning off the clamp transistors. |
Upon switch off of the 34, C74 will discharge slowly enabling the regulator to sustain 0/p voltage. As C74
discharges the regulator input voltage will fall (become more positive) and C69 will discharge through D31. When
the regulator input voltage comes within 2V of the output voltage (i.e. input approx. —20V) T13 will turn off, turning
on the audio clamp transistors.
SWITCHING
Fig 1 is a schematic diagram illustrating how the electronic switching controls the signal flow through the 34.
Switching is carried out using logic circuits to control analogue switches.
Disc, Radio and CD (Aux) inputs are connected to a common signal bus via analogue switches. Tape record is
permanently connected to the signal bus. Selection of Disc, Radio or CD (Aux) will enable signal from the appropriate
input onto the signal bus, hence Tape record. The other two inputs will be cancelled. Signal from the bus is only
transmitted onto the main signal path through the 34 if Tape replay is not selected. Selection of Tape replay
overrides the signal bus enabling Tape input onto the main signal path, thus providing the monitoring facility.
Fig. 1
Disc, Radio and CD
QUAD 34 service data
LOGIC
CONTROL
FOR
INPUTS
AA AA
%
SCHEMATIC SIGNAL FLOW DIAGRAM
|) RAD
DISC
)
DE
)
TAPE
MON С
F1
SL
С
C
(
| BALANCE
DA a
LOGIC
CONTROL
FOR
FILTERS
TOR.H.
CHANNEL
O o
FILTERS
O о
OUTPUT
Control logic of the Disc, Radio and CD (Aux) analogue switches is based around the triple NOR gate latch of 1C11.
Fig. 2
e
— — О Оо >
—\ © — © | ©
© © © —
The output of the NOR gates are used to control the analogue switches of the Disc, Radio and CD (Aux) inputs. The
inputs to each NOR gate are the outputs from the other two NOR gates.
Selection of, say, Radio will result in an instantaneous logic 1 being applied to pin 10, thence to the control pins of
the Radio analogue switches. Also the logic 1 will be applied to the inputs of the Disc and CD NOR gates, (pins 13
and 5) making their respective outputs zero. The two zero's are applied to the Radio NOR gate inputs, pins 8 and 9,
hence pin 10 the Radio control pin will sustain logic 1. The logic 1 is also used to turn on indicator led D16 via T6.
The process is similar for selection of CD and Disc.
The differentiator action of C44 and R62 ensures that Radio is automatically selected upon switch on of the 34.
QUAD 34 servicedata
Tape
Operation of the tape switch is based around a D-type flip flop (IC14). This has complementary outputs Q (pin 13)
and Q (pin 12). Data on pin 9 is transmitted to pin 13 on each positive clock (pin 11) transition.
Connected as shown, data is determined by the o/p on pin 12, Q. Assuming initial conditions of Q (pin 13) at logic
high then Q (pin 12) will be at logic low. The outputs will enable two of the analogue switches of IC1 (pins 3, 4, 5
and 6, 8, 9) and disable the other two (pins 1, 2, 13 and 10, 11, 12), thus selecting tape input. Also D18 will
illuminate via T8. | _
Further selection of Tape will apply a positive transition to clock, (pin 11), and data on pin 9 set by Q (pin 12) will
be transmitted to pin 13, hence the outputs change their states. Under these conditions the analogue switches of
IC1 will be enabled in the opposite way to the previous configuration. Signal from the common bus (Disc, Radio or
CD) is then transmitted through the set and Tape replay is disabled. Selection of Tape again will cause the outputs to
change states and once again Tape replay is enabled.
Initial conditions are defined by the differentiator action of R83 and Cb5. Upon switch on a short positive pulse is
applied to the reset pin (pin 10) of the flip flop. This sets Q (pin 12) to logic high hence ensuring tape is not selected
initially.
Mono
Selection of mono links two points in the left and right channel circuits by means of an analogue switch. The switch
is controlled in the same way as for selection of tape using a D type flip flop (see above).
Filter Switching
Filtering is controlled by analogue switches within the filter circuit. Again the control logic is based around D type flip
flops which are used in much the same way as described for Tape selection (see above). Selection of Filter 1 will
enable the appropriate analogue switches in the filter circuit via the D type flip flop. Also the select pulse will be
applied to the reset pin of the D type flip flop associated with Filter 2, hence ensuring that selection of Filter 1 |
cancels Filter 2. Selection of Filter 2 will cancel Filter 1 in an identical manner. Initial conditions are defined by the
differentiator action of C68, R100 and C79, R108. Upon switch on the action of these components is to apply a
positive pulse to the reset pins of the two flip flops, ensuring that neither Filter 1 or Filter 2 is selected.
Slope operation is again based around a D type flip flop controlling an analogue switch within the filter network.
However since Slope can only be selected if Filter 1 or Filter 2 is selected and Slope is automatically selected with
no led indication (see filters) when neither Filter 1 or Filter 2 is selected then additional circuitry is employed to detect
and enforce these conditions. _
When Filter 1 and Filter 2 are off, the Q outputs of their respective flip flops (pin 12 of IC15 and pin 2 of IC16) are
at logic high. Neither D23 or D24 will conduct so the reset pin of the Slope flip flop (pin 10) will be at logic high.
This leaves the flip flop locked in the off mode regardless of whether the Slope button is selected or not. However
the logic high on pin 10 is applied to the control pin of the steep slope analogue switch via D29. Under these
conditions Slope is automatically selected but the Slope indicator led remains off. This provides a rapid tail off in
frequency response above the audio band.
When either filter is selected then the Q output of the associated flip flop will be at logic low and either D23 or D24
will conduct. This will set the reset pin of the Slope flip flop (pin 10) at logic low enabling Slope to be selected.
Operation of the Slope switching circuit is then the same as the Tape input switching circuit described above.
Initial conditions are defined by the states of Filters 1 and 2, which are set to be off upon switch on of the 34.
TONE CONTROLS
The Tilt and Bass circuits of the 34 are based around one Op Amp, per channel, IC13 in the case of the right hand
channel, and IC12 for the left hand channel.
Tilt Circuit
The function of the Tilt circuit is to provide a gradual change in output level across the frequency spectrum, centered
on OdB, (see fig 3).
40 100 1K 10K 20K
Hz
Fig. 3
QUAD 34 service data
The Tilt circuit may be built up in three stages.
GAIN
O
= Во
Ра. 4 (а) (6)
Rf
GAIN
° © OdB FREQUENCY
Fig. D (a) (b)
1. In the circuit shown in fig 4(a) gain is determined by:
At low frequency Rf
Rin
At high frequency Rf//Rp
Rin
If Rf = Ri, this would give a frequency response as shown in fig 4(b).
Similarly the frequency response for the circuit shown in fig 5(a) is as shown in fig 5(b).
2. If the two circuits of figs 4 and 5 were added together the resulting frequency response would be flat at OdB. If
a pot is then added as shown in fig 6 (a) the response would only remain flat if the pot were in the central
position. Displacement of the pot to either of the end extremes would yield one of the two responses shown in
fig 6(b).
Ri Rf
GAIN
C
AP POT Rp Í TT
›
[ > 998 FREQUENCY
GAIN
+ > dB FREQUENCY
Fig. 7 (a) Co (b)
3. Crossing of Rf and Rin as shown in fig 7(a) results in the two most extreme responses being as shown in fig 7(b).
QUAD 34 service data
Bass Circuit
The Bass control uses two separate circuits for lift and step modes. For this reason the resistance track in the Bass
pot is discontinuous as shown in fig 9(a).
Bass Lift
Fig 8(a) shows a simplified bass lift circuit. The Tilt network here is represented by ZT1 and ZT2 which are equal
when the Tilt switch is in the zero position.
At medium frequencies the capacitive reactances are negligible and the gain is set by ZT1 and ZT2. At low frequencies
the reactance of Co becomes significant and, if R bass is selected, reduces the negative feedback hence increasing
the gain. R bass simply varies the frequency at which the turnover point occurs.
Cin provides a second turnover point further down the spectrum thus defining the frequency at which the gain is
maximum and ultimately reducing the gain to unity. The resulting curves are shown in fig 8(b).
Bass Step
Bass step is provided by the low frequency potential divider of C37, C39, R48 and RV3(b), (in the case of the right
hand channel). Variation of RV3(b) will set the frequency at which attenuation begins. C37 and C39 set the ultimate
attenuation to approx. —6dB. This value is slightly modified by R48.
AN ZT2
220n
Fig. 8(a)
+16
+12
+8
+4
dB O
—4
—8
10 100 1K
Fig. 8(b) ne
—3 +3
300Hz —2 +2
3 201 170Hz : 3 2 7 1 +1
000 | loo 66 | ra
47 | 13K| 9K1 9K1|9K1|9K1 |
| — 3dB | -+1—
4K7 9K1 |
à- 6dB | _ +2 —2
2K7 | 9K1 |
— 9dB — +3 -3
3K3 13K |
| | q |
DB. A
Fig. 9 (a) BASS POT (b) TILT POT
QUAD 34 service data
The filter circuit is designed to cater for 5 different variables, these being no filters, Filter 1 only, Filter 2 only, Filter 1
Slope and Filter 2 Slope.
Note: When neither filter is selected Slope is automatically selected but this is not indicated by the slope led, (see
Switching page 4). This rapid tail off in frequency response discriminates against frequencies above the audio band.
When Filter 1 or Filter 2 is selected the upper cut off frequency is lowered (see fig 10). The rate of attenuation will
be 6dB/octave.
Selection of Slope with either filter increases the slope to 12dB/octave. Also with Slope selected the upper cut of
frequency (-3dB point) for a given filter is modified so that filtering attenuation begins at the same point.
1K Hz 10K 20K
Fig. 10
A MONO BC D
CONTROL POINT CONTROL congo
IC2O +8-6V
R77 ISK y R93 10K
cs |
|
LA
9 — — — — —Ñ
€
RBO 39K
O
INPUT
Fig. 11
These variations are achieved using logic to control analogue switches within the filter circuit, (see fig 11). For
6dB octave filtering the circuit is connected as a buffered R-C filter (12b). For 12dB/octave filtering (Slope) the circuit
is connected in a Sallen-Key configuration as shown in fig 12(a).
The values of R and C in either network are determined using the four analogue switches to connect (in the case of
the right channel shown in fig 11) R77, R78, R79, R80, R93, R94, C63, C64, C/2 and C73 in various
configurations. (Similarly for the left hand channel).
QUAD 34 service data
Fig. 12 (a) | (b) 1
1.
(1)
(ii)
(ii)
(1)
(1)
(1)
(ii)
10
il
ВТ R2
R
O VW 1 +
C
C1
Filter 1
With Filter 1 selected and no slope, the analogue switch ‘D’ (fig 11) is disabled and A B and C are enabled.
Analogue switch A connects R77 in parallel with R78 and R79 in parallel with R80. These resistors together
with R93 and R94 form a balanced bridge circuit with no potential difference across C63, hence this component
plays no active part.
Analogue switch B connects C64 across C63 hence this component also plays no active part.
Analogue switch C connects C72 in parallel with C73. The equivalent circuit is shown in fig 12(b) where;
R= ((R77//R78) + R93)//(R79//R80) + R94)
C= C72 + C73
Filter 2
Conditions are much the same as in 1 except that analogue switch A is no longer enabled therefore R78 and
R79 are left out of circuit.
The equivalent circuit is shown in fig 12(b) where;
В = (R77 + R93)//(R80 + R94)
C= C72 + C73
No Filters
Analogue switches A and D only are enabled.
Analogue switch A makes connections as described in 1(i).
Analogue switch D switches in the feedback circuit. This makes the effects of R94, R79 and R80 negligible.
The circuit becomes a sallen key filter, the circuit for which is shown in fig 12(a) where;
R1 = R77//R78
R2 = R93
C1 = C73
C2 = C63
Filter 1 with slope
All analogue switches are enabled.
Analogue switches A, B, C make connections as described in 1(1), (11) and (iii) respectively.
Analogue switch D makes connections as described in 3(ii).
The circuit becomes a sallen key filter as shown in fig 12(a) where;
R1 = R77//R78
R2 = R93
C1 = C72 + C73
C2 = C63 + C64
Filter 2 with slope
The conditions are much the same as in 4 except that analogue switch A is no longer enabled.
The equivalent circuit is as shown in fig 12(a) where;
R1 = R77
R2 = R93
C1 = C72 + C73
C2 = C63 + C64
QUAD 34 service data
fault finding
Fault finding is best carried out using the flow diagram shown in fig 13. It should be noted however that the diagram
caters for single fault conditions only and is not suitable for diagnosing multiple faults.
Exit from the diagram will be at one of the 35 diagnoses, each of which is clearly defined below. Since the diagram
is based on likely or recurring faults some of the diagnoses are arrived at by default. This form of reasoning may
occasionally provide an incorrect answer. Always check that the diagnosis seems reasonable by looking at the circuit
diagram.
Reference is made in the diagram to isolating the regulator o/p and measuring the o/p voltage. This is best done by
removing the regulator and resoldering it to the rear of the pcb, leaving the o/p pin disconnected. The o/p voltage
can then be measured between the o/p pin and the +ve 8.6V HT rail, and should be —18V with respect to this rail.
Where it is necessary to measure HT voltages, see pages 15 and 16.
DIAGNOSES
1. 1C18.
2. Fuse blown due to spurious AC power supply spike.
3. (i) Check that the voltage selector is set correctly.
(i) L1 (Transformer).
4. This fault is most likely to occur with pre-serial number 2000 34's. Replace with a new transformer which will
have two electrically redundant tags. These should be cut off after which the transformer may be located on the
p.C.b. The remaining tags should be uncut and bent under the p.c.b. to increase mechanical rigidity.
1021 U/S.
) IC7 U/S.
i) T1, T2 U/S.
ii) 1C22 U/S.
iv) Ribbon Cable O/C.
|) 1C8 U/S.
) T3, T4, U/S.
|) 1C22 U/S.
iv) Ribbon Cable O/C.
) For 34's post S/N 8000 1C24 U/S.
i) 1C2 U/S.
9. 102 U/S.
10. (i) For 34's post S/N 8000 IC26 U/S.
(ii) IC1 U/S.
11. (1) For 34's pre S/N 8000 IC3 U/S.
For 34's post S/N 8000 IC?5 U/S.
12.(i) For 34's pre S/N 8000 IC4 U/S.
For 34's post S/N 8000 IC25 U/S.
13. () D32 U/S. Particularly on 34's pre S/N 6000.
(ii) IC1 U/S.
(ii) For 34's post S/N 8000 IC27 U/S.
14. () For 34's pre S/N 8000 IC5 U/S.
For 34's post S/N 8000 1C27 U/S.
(i) 1C19 U/S.
(iii) 1C12 U/S.
(iv) 1C9 U/S.
(М) D/J volume pot.
15. (1) For 34's pre S/N 8000 IC6 U/S.
For 34's post S/N 8000 IC27 U/S.
(ii) 1C20 U/S.
(ii) 1C13+U/S.
(iv) 1С10 U/S.
(v) D/J volume pot.
11
QUAD 34 service data
16. 1C2 U/S.
17. (1) Check that disc board edge connector is properly located.
(ii) 1C22 U/S.
18. For 34's post S/N 8000 1C24 U/S.
19. For 34's post S/N 8000 IC26 U/S.
20. 1C14 U/S.
21. For 34's post S/N 8000 1С25 U/S.
22. A touch hot IC is an indication that the IC itself is faulty.
23. Associated BC183 U/S.
24. Associated BC183 U/S.
25. 1011 U/S.
26. (1) Associated BC183 U/S.
(i) Led U/S.
27.1C15 or IC16 U/S.
28.1C17 U/S.
29. CMOS IC S/C. To isolate the faulty IC unsolder pin 14 from IC1, 1C2, 1C11, 1C14, IC15, IC16, 1C17, 1C18 and
1С22 in turn, using a process of elimination to determine the faulty component.
30. Diagnosis is as for 29 except that both pins 14 and 7 should be disconnected.
31.(1) L1 (transformer).
(1) D34.
32. High current Op Amp. Isolate HT pins of each Op Amp in turn using a process of elimination to isolate the faulty
component.
33. 1C14 U/S.
34.1C22 U/S.
35. Diagnosis is as for 29 except that pin 7 of the IC's listed should be disconnected.
12
START
DOES
34 HAVE
ANY AUDIO
O/P OR LED
INDICATION
IS
THERE
RECORD O/P
ON B/C FOR
ALL INPUTS
Y
Y PRE-AMP AND N
IS
FAULT
COMPLETELY
INDEPENDANT
OF INPUT
SELECTED
DOES
MONO
FUNCTION
(AUDIBLY)
REPLACE
FUSE AND DIAGNOSIS
RE-APPLY VOLTS 34
VIA VARIAC
DIAGNOSIS
23
DIAGNOSIS DIAGNOSIS
2 28
DIAGNOSIS
In 3
IS
DIAGNOSIS L1
4 (TRANSFORMER)
SECURED
Fig. 13
DOES
EACH
INDICATOR
LED
FUNCTION
OK
DOES
EACH
SELECTED
BUTTON
FUNCTION
(AUDIBLY)
A
PARTICULAR
LED
NOT
LIGHT
DIAGNOSIS
26
DIAGNOSIS
1
DIAGNOSIS
22
VOLTAGES
CORRECT
DIAGNOSIS
21
>
ARE
ALL
HT
VOLTAGES
CORRECT
DOES
MONO
BUTTON
FUNCTION
CORRECTLY
IS
FAULT
EXCLUSIVE TO
TAPE
RECORD .
IS
Y FAULT
B/C
IS
FAULT
B/C
DIAGNOSIS
13
L —
—_—
DIAGNOSIS
12
DIAGNOSIS
27
DIAGNOSIS
33
DIAGNOSIS
11
DISCONNECT
он
4 —
DIAGNOSIS
6
DIAGNOSIS
31
IS
R84
DISCONNECTED
ARE
+8.6V
AND —9.4V
HT VOLTAGES
OK
N
ARE
REGULATOR
INPUT
VOLTS
APPROX
30V
IS
FAULT
WITH
POSITIVE 7.5V
HT VOLTAGE
ONLY
N
<+ |
DIAGNOSIS
13
DIAGNOSIS
12
DIAGNOSIS
6
L/C ONLY
DIAGNOSIS
15
DIAGNOSIS
14
IS
FAULT Y
B/C
DO
THE
APPROPRIATE
LEDS
WORK
CORRECTLY
IS
THE
FAULT
COMMON TO
RADIO AND
CD/AUX
UAD 34
service data
VOLTAGES
CORRECT
DIAGNOSIS
16
DIAGNOSIS
8
DIAGNOSIS
10
DIAGNOSIS
31
DIAGNOSIS
7
DIAGNOSIS
9
IS
FAULT
WITH
POSITIVE 7.5V
HT VOLTAGE
ONLY
ISOLATE
REGULATOR
AND
MEASURE O/P
VOLTS
(SEE NOTES)
DIAGNOSIS
29
DIAGNOSIS
5
>
IS
FAULT
AFFECTING
DISC
DIAGNOSIS
19
DIAGNOSIS
32
DIAGNOSIS
35
DIAGNOSIS
30
15
FAULT
WITH
NEGATIVE
7.5V HT
VOLTAGE
ONLY
IS
FAULTY
LED DIM
WHEN
SELECTED
DIAGNOSIS
24
DIAGNOSIS
17
DIAGNOSIS
18
DIAGNOSIS
25
DIAGNOSIS
20
13
test procedure
QUAD 34 service data
Complete testing of a 34 may most easily be carried out by using the equipment listed below and interconnecting
these units as illustrated in fig 14. Any signal cables used for interconnecting should be screened. The 34 cover
should be removed for initial tests. Reference is made to testing on 240V, clearly the same results should be
expected if testing on 110V though the current consumption will be larger.
TEST EQUIPMENT
Sine/Square A.F. Signal Generator
AC Microvoltmeter
Oscilloscope
Anti RIAA Network (as shown in fig 18)
Mono Amplifier
Headphones or Loudspeaker
4 x 5 pin Din Plugs
2 x Phono Plugs
Voltmeter
AC MICROVOLTMETER OSCILLOSCOPE SIGNAL GENERATOR
A @ © ©
ALE С © © ®
5 © Ce© loe® | ch?
CHI © +
$2 51
—— | Sy SA
MONO AMPLIFIER
34 © ©
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VARIAC
CITI
Fig. 14
The test equipment should be earthed from one localised common earth point to minimise the effects of earth loop
hum.
14
QUAD 34 service data
Din Plugs
Three of the Din plugs should be made up to simulate 100mV loads, to be used in conjunction with noise testing.
This is done by connecting two resistors as shown in fig 15(a).
The other Din plug should be used to link the record pins of the tape socket to the replay pins such that the right
channel record is connected to the left channel replay and vice versa as shown in fig 15(b).
Short circuit each of the phono plugs.
Fig. 15 (a) (b)
Connections
S1 to Radio left channel input
S2 to left channel output
Controls
Variac: output volts — zero
34: Power — on
Bass, Tilt — zero
Balance — central
Volume — 21
Tape replay sensitivity — 300mV
Tape record level — 300mV
CD sensitivity — 500mV
Oscilloscope: Ch1 — 0.5V/cm
Ch2 — 0.1V/em
Timebase — 0.5ms/cm
Signal Generator: Mode — Square Wave
Frequency — 650Hz
Peak to Peak Voltage — 0.2V
Microvoltmeter: Range — suitable for 500mV reading
Bandwidth — 10Hz — 100kHz
1. POWER
Increase the output of the variac to 240V whilst observing the current consumption of the 34 which should not
exceed 1omA (typically TOmA). The power outlet socket should be checked by connecting to it a suitable piece of
equipment. Power to the equipment should then be controlled by the 34 power switch. Remove the plastic power
supply cover. Measure the 4 supply rails which should be +8.6, +7.5, —7.5 and —9.4V as shown on the diagram
below. Replace the plastic power supply cover.
15
QUAD 34 service data
FARTH
+8.6V
+7.5V
—7.5V
-9.4V
T11
T9
110
T7
TH
Fig. 10 T6
2. OUTPUT
Observe the oscilloscope Ch1 beam which should show a square waveform trace as shown in fig 17. Switches S1
and S2 should then be connected so as to drive the right channel input and monitor the right channel output. when
a similar waveform should be displayed. Some square waves may show some overshoot. This is due to the >20kHz
Slope filter (see page 6).
Fig 17
16
QUAD 34 service data
3. CHANNEL BALANCE
Move the balance slider towards the bottom of its travel, the output waveform should progressively increase to a
maximum at the bottom extreme. Move the balance slider upwards and signal should progressively decrease to
zero at the top extreme.
Drive the left channel input and monitor the left channel output where the opposite to this should be obtained.
Select mono and move the balance slider to the upper extreme. The waveform peak to peak value should be at a
maximum of 0.6V decreasing to zero as the balance slider is moved to the lower extreme. Drive and monitor the
right channel where the opposite to this should be obtained.
Select stereo mode and 10kHz sine waves at 100mV RMS. With the balance slider in the central position note the
output level reading on the AC microvoltmeter. Move the balance slider to the lower extreme, the output level should
increase by approx 2.5dB. Move the balance slider to the upper extreme, the output level should fall by approx
65dB.
Drive and monitor the left channel where the opposite to this should be obtained.
Centralise the balance slider.
4. INPUT SELECTOR AND OUTPUT LEVEL
In the following tests full output’ refers to the waveform shown in fig 17. For ‘no output’ waveforms may be spikey
due to the finite level of crosstalk. Select 650Hz square waves with peak to peak value at 0.2V.
RADIO AND TAPE
(a) Drive and monitor the left channel to obtain a full output waveform. Monitor the right channel to obtain no
output. Drive and monitor the right channel to obtain full output. Monitor the left channel to obtain no output.
(b) Insert the Tape link plug into the Tape input socket. Select Tape and drive and monitor the right channel to
obtain no output. Monitor the left channel to obtain full output. Drive and monitor the left channel to obtain no
output. Monitor the right channel to obtain full output.
Failure to achieve the correct output level suggests that Tape record and replay levels are not set to the same
value. Press Tape, to re-select Radio.
CD/Auxiliary
Remove the signal input lead from the radio input and plug this into the CD/Auxiliary socket and select this input. For
units which are pre-serial number 8000 with Auxiliary input sensitivity of 100mV repeat test (a) as carried out for
Radio. For post-serial number 8000 units with Auxiliary/CD input sensitivity of SOOMV increase the signal generator
output to 1.8V peak to peak and repeat test (a) as carried out for Radio.
Disc
Remove the signal input lead from the Auxiliary input. The output from the signal generator should be connected to
S2 via the anti RIAA circuit. In order to overcome the 75dB attenuation of the anti RIAA circuit, the input to this
circuit should be set as shown below.
Disc module Signal generator o/p level
100uV 4V peak to peak
200uV 8V peak to peak
3mV 22V peak to peak
It may be necessary to amplify the signal generator output to achieve these levels. For M/c disc input drive from the
low Z output of the anti RIAA network. Fitting of 34 cover will reduce hum.
Select Disc and repeat test (a) as carried out for Radio.
INVERSE RIAA NETWORK
1
Connect low impedance signal generators to terminals 1 and E.
6.8K 46nF Connect 600R signal generators to terminals 2 and E.
Connect terminals 4 and E to 3mV disc input.
GOOR , Connect terminals 5 and E to M/C disc inputs.
47K
20 «> «> AN <> ——O 4
22R
16nF 5
27R dt
DR
E O- | —-O E Fig. 18
Disconnect the RIAA circuit.
17
QUAD 34 service data
5. TONE AND FILTERS
Remove the signal input lead from the Disc input. Adjust the signal generator output level to 0.2V peak to peak and
apply this direct to S2. Plug the signal input lead into the Radio input and select Radio, and vol. 18.
Fig 19 shows how the output waveform is modified for each of the tone and filter settings.
Fig 19 was drawn with the timebase on the 2mV/cm range and sensitivity on the 0.2V/cm range but these were in
the uncalibrated mode to illustrate more clearly the tone and filter effects. Fig 19 (a) shows the reference output
waveform.
The checks should be carried out on both channels.
Fig. 19
(a) (b) (с)
Reference Output Waveform Filter 1 and slope Filter 2 and slope
(f)
Tilt +3 —3 Tilt +2 —2 Tilt +1 —1
(9) (A)
Tilt —1 +1 Tilt —2 +2 Tilt —3 +3
18
QUAD 34 service data
Fig. 19 (continued)
(1) (k) (1)
Bass 300Hz Bass 170Hz Bass 100Hz
(m) (n) (0)
Bass 3dB Bass 6dB Bass 9dB
6. VOLUME POT
Return all tone and filters to zero and set volume to 21.
Reset oscilloscope timebase and sensitivity and set the signal generator to apply 10kHz sine waves at 100mV Rms.
Observe the AC microvoltmeter to ensure that the output levels from both channels are equal, within + 0.5dB.
Decrease the volume from 21 to O checking the output levels for each setting (listed below) and adjusting the AC
microvoltmeter range as necessary. Repeat the test on the other channel.
The figures below show the attenuation level in dB's with respect to full output for each volume setting. Also quoted
are the actual volume circuit amplification and attenuation levels. Tolerance is O.5dB.
Numerical Setting Attenuation (w.r.t. full o/p) dB Amplification (vol. circuit) dB
21 О 31.7
20 2 29.7
19 4.1 27.6
18 6.3 25.4
17 8.5 23.2
16 10.8 20.9
15 13.2 18.5
14 15.6 16.1
13 18.0 13.7
12 20.5 11.2
11 22.9 8.8
10 25.4 6.3
9 27.8 3.9
8 30.3 1.4
7 32.8 —1.1
6 35.3 —3.6
5 37.8 —6.1
4 42.8 —11.1
3 47.8 —16.1
2 52.8 —21.1
1 57.8 —26.1
0 89.0 —00
Return the volume to 21 and adjust the microvoltmeter accordingly.
19
QUAD 34 service data
7. CROSSTALK
Remove the signal input lead and cover. Solder a 1K resistor across the Radio right channel input. Ensure that S1 is
set to drive the left channel then re-connect the leads. Note the output level in dB's. Monitor the output from the
right channel which should be at least 50dB below full output. Remove the signal input lead and solder the 1K
resistor across the Radio left channel input. Repeat the test driving the right channel and monitoring the output from
the left channel to obtain the same results.
N.B. If test equipment leads are not screened or correctly routed it may be difficult to achieve this figure.
8. NOISE
Remove the 1KQ resistor and all leads. Fit the cover on to the 34. Plug in the AC supply lead, the output lead and
the 1K DIN plug dummy loads into Radio, Aux/CD and Tape. Connect a suitably screened approx, 1-10mV
cartridge to the 3mV disc input to represent the correct loading. If a moving coil cartridge is being tested use the s/c
phono plugs to represent the source impedance.
With the volume control at zero the output level with any selected input should be at least —90dB with respect to full
output. If "A" weighting is used this figure should exceed —100dB.
With the volume at 21 the output levels should be as shown below, again with respect to full output.
INPUT ‘A’ weighted S/N ratio (dB) Flat S/N ratio (dB)
Radio 88 80 |
Auxiliary (pre-8000) 88 80
CD/Aux (post 8000) 87 79
Tape 87 79
Disc 3mV 75 65
100uV 68 53
200uV 72 57
With Disc selected connect an amplifier and headphones/loudspeaker system and listen to the noise. Randomly
switch all tone and filters listening for electrical clicks. Also switch randomly all input buttons again listening for
clicks. Clicks due to dirty switch contacts can be cured by squirting the faulty switch with switch cleaner such as
WD40.
20
QUAD 34. service data
modifications
Approx Serial Number 2000
ISS 2 p.c.b. introduced incorporating the following changes;
1. Wire links replaced by printed copper links on the top side of the p.c.b.
2. Two holes added in the power supply area of the p.c.b. These are to house two electrically redundant tags added
to the transformer to ensure that the transformer is mechanically secured.
Approx Serial Number 3700 FEBRUARY 1983
R55 and R60 changed from 680K to 2M2, stock number R2M20J1. This gives improved bass response.
Approx Serial Number 4000 MARCH 1983
C83 added to decouple the HT rails to earth. C83 is soldered to the rear side of the p.c.b. and on some 34's is
47 nf, stock number C47NQOZL soldered between negative rail and earth whilst on other units C83 is 680nf, stock
number COSONKT soldered between positive rail and earth.
Serial Number 4130 MARCH 1983
Red filter 1, filter 2 and slope buttons replaced by similar brown buttons, stock numbers MBOOF1B, MBOOF28
and MBOOSLB respectively.
Serial Number 6001 JUNE 1983
ISS 4 p.c.b. introduced incorporating the following changes;
1. Radio analogue switch control is now derived directly from pin 10 of IC11. This reduces selection clicks.
2. C81 and C82, 47n stock number C47NOZL added to minimise the effects of external RF clicks.
3. R125, 220Q stock number R220RG1 added to protect zener diode D32.
4. C44 moved from the input selector board to the main p.c.b. whilst keeping the same electrical location.
Serial Number 8001 NOVEMBER 1983
ISS b p.c.b. introduced incorporating the following changes:
1. C83 removed. C84, 22u stock number C22UQOZE fitted to the top side of the board between negative rail and
earth. C58 is moved to be connected between positive rail and earth.
2. Tape and Auxiliary input circuits completely changed. Auxiliary input sensitivity is now 300mV or 100mV
according to the plug in flag selection. With 300mV sensitivity auxiliary is suitable for use with compact disc.
Serial Number 8305 DECEMBER 1983
34's are now fitted with CD select buttons stock number MBOOCDY, and chassis print is changed accordingly.
21
QUAD 34 service data
complete parts list
Component Value Stock No. Previous Previous Comments
Ref. Value Stock No.
R3 H60R R560RJ1
R4 470R R470RJ1
R7 470R R47ORJ1
R8 680R R680RJ1
R11 100K R100KJ1
R12 100K R100KJ1 Removed at 1SS 5
R13 100K R100KJ1
R14 100K R100KJ1 Removed at 1SS 5
R15 2K2 R2K20G1
R16 FLAG Removed at ISS ©
R17 2K2 R2K20G1
R18 FLAG Removed at ISS b
R19 39K R39KOJ1 Removed at ISS 5
R20 39K R39KOJ1 Removed at ISS 5
R25 2K2 R2K20G1
R26 2K2 R2K20G1
R27 FLAG Q34300R
R28 FLAG Q34300R
R29 10M R1OMOKB
R30 10M R1OMOKB
R31 10M R1OMOKB
R32 10M R1OMOKB
R33 4K7 R4K70J1
R34 54K9 R54K9FN
R35 4K99 R4K99FN
R36 750K R750KG1
R37 4K7 R4K70J1
R38 54K9 R54K9FN
R39 4K99 R4K99FN
R40 750K R750KG1
R41 750R R/50RFN
R42 39K R39KOJ1
R43 750R R750RFN
R44 39K R39KOJ1
R45 1K3 R1K30G1
R46 1K3 R1K30G1
R47 100K R100KJ1
R48 100K R100KJ1
R49 10K R1OKOJ1
R50 1M R1MOOJ1
R51 91K R91KOG1
R52 91K R91KOG1
Rb3 56K R56K0G1
R54 820K R820KJ1
R55 2M2 R2M20J1 680K ROBOKJ1 Changed at approx S/N 3700
R56 91K R91K0G1
Rb7 91K R91KOG1
R58 56K RB6KOG1
R59 820K R820KJ1
R60 2M2 R2M20J1 680K R680KJ1 Changed at approx S/N 3700
R61 10K R10KOJ1
R62 1M R1MOOJ1
R63 91K R91K0G1
R64 91K R91K0G1
R65 DOK R56K0G1
R66 820K R820KJ1
R67 91K R91K0G1
R68 91K . R91K0G1
R69 56K R56K0G1
R70 820K R820KJ1
R71 10K R1OKOJ1
R72 1M R1MOOJ1
R73 15K R15KOJ1
R74 8K2 R8K20J1
R75 18K R18K0J1
R76 39K R39KOJ1
R77 16K R15KO0J1
R78 8K2 R8K20J1
R79 18K R18K0J1
R8O 39K R39KOJ1
R81 10M R1OMOKB
R82 1M R1MOOJ/1
R83 1M R1MOQOJ1
R84 180R R180RJ1
R85 300R R300RJ1
22
QUAD 34 service data
Component
Ref.
R86
R87
R88
R89
R30
R91
R92
R93
R94
R35
R96
SF10
Value
2M2
2 M2
10M
1M
1M
10K
22K
10K
22K
10K
Flag Record Link to CD
Flag Record Link to CD
Flag Tape 100mV Replay
Flag Tape 100mV Replay
Flag Tape 100mV Record
Flag Tape 100mV Record
Flag Tape 300mV Replay
Flag Tape 300mV Replay
Flag Tape 300mV Record
Flag Tape 300mV Record
Flag CD 500mV
Flag CD 500mV
5V6 Zener
5V6 Zener
6V8 Zener
0V8 Zener
6V8 Zener
6VE Zener
Stock No.
R2M20J1
R2M20J1
R1OMORKB
R1MO00J1
R1MO0J1
R1OKOG1
R22K0J1
R10KOG1
R22K0J1
R1K00J1
R1K00J1
R1K00J1
R1OMOKB
R1MOOJ1
R33KOJ1
R22K0J1
R3K30J1
R3K30J1
R2M20J1
R2M20J1
RTOMOKB
R1MOOJ1
R3K30J1
R33KOJ1
R8K20J1
R8K20J1
RTOMOKB
R1MOOJ1
R330KJ1
R3K30J1
R2K70J1
R2K20G1
R1K00G1
R2K70J1
R2K20G1
R1KOOGT
R8K20J1
ROK10J1
R2ZORGT
R39KOJ1
R39K0J1
R39K0J1
R39KOJ1
Q34V5CD
Q34V5CD
Q34300P
Q34300P
R1M00J4
R1M00J4
R1M00J4
R1M00J4
R1OKOJ4
R10KOJ4
R10KOJ4
R1OKOJ4
Q34X1X2
Q34X1X2
Q34100P
034100P
Q34100R
Q34100R
Q34300P
Q34300P
Q34300R
Q34300R
Q34V5CD
Q34V5CD
D795V6A
D795V6A
D886V8A
D886V8A
DESEVSA
D886V8A
Previous
Value
6V8 Zener
OV8 Zener
6V8 Zener
6V8 Zener
6V8 Zener
Previous
Stock No.
D886V8A
D886V8A
D886V8A
D886V8A
D886V8A
Comments
Added at
Added at
Added at
Added at
Added at
Added at
Added at
Added at
Added at
Added at
Added at
Added at
Added at
Added at
Added at
Added at
Added at
Removed
Removed
Removed
Removed
Removed
ISS 4
ISS b
ISS 5
ISS b
ISS ©
ISS b
ISS b
ISS D
ISS D
ISS ©
ISS ©
ISS 5
ISS 5
ISS 5
ISS 5
ISS 5
ISS 5
at ISS 5
at ISS 5
at ISS 5
at ISS 5
at ISS 5
Component
Ref.
D12
D13
D14
D15
D16
D17
D18
D19
D20
D21
D22
D23
D24
D25
D26
D27
D28
D29
C66
Value
TLG124
TLG124
TLG124
TLG124
TLG124
TLR124
TLR124
TLR124
IN4148
IN4148
IN4148
IN4148
IN4148
IN4148
IN4148
15V Zener
IN4148
12V Zener
TLG124
VM18
330n
330n
1004
1004
Stock No.
BLG124P
BLG124P
BLG124P
BLG124P
BLG124P
BLR124P
BLR124P
BLR124P
D1N4148
D1N4148
D1N4148
D1N4148
D1N4148
D1N4148
D1N4148
D8815VA
D1N4148
D8812VA
BLG124T
DVM18XX
C33ONKS
C330NKS
C100UME
CTOOUME
CTOOUME
C100UME
C2U20KJ
C47NOFA
C15NOFA
C47POKJ
C2U20KJ
C47NOFA
C15NOFA
C47POKJ
C15NOFA
C470NKS
C15NOFA
C470NKS
CTOOUME
C100UME
C1NOOJP
C1NOOJP
C15P0OJI
C15POJI
C220NKS
C220NKS
C220NKS
C220NKS
C3N30JP
C1NOOJP
C3N30JP
C1NOOJP
CAN70ZM
C3N30JP
CTNOOJP
C220NKS
CTOOUKT
C3N3OJP
C1NOOJP
C68NOKS
C68NOKS
C220NKS
C100UKT
C47NOZL
C4N70ZM
C100UME
C22U0ZE
C100UME
C680PKJ
CTNOOJP
C680PKJ
C1NOOJP
C47NOZL
C4N70ZM
Previous
Value
6V8 Zener
6V8 Zener
oV8 Zener
330n
330n
680n
680n
Previous
Stock No.
D886V8A
D&86V8A
D886V8A
C3IONKS
C33ONKS
CESONKS
COBSONKS
QUAD 34 service data
Comments
Removed at ISS b
Removed at 155 5
Removed at ISS b
Removed at ISS b
Removed at ISS b
Removed at ISS b
Removed at ISS b
24
QUAD 34 service data
Component
Ref.
C67
C68
C69
C70
C71
C72
C73
C74
C75
C76
C77
C78
C79
ceo
C81
C82
C83
C84
C85
C86
СВ
C88
C89
C90
C91
C92
IC1
IC?
IC3
IC4
ICH
ICO
IC7
IC8
ICY
IC10
IC11
IC12
IC13
IC14
1С15
1С1 6
IC17
IC18
IC19
1C20
IC21
Value
47n
4n7
1004
100m
1004
1004
1004
4016 Quad Transmission Gate
4066 Quad Transmission Gate
071
071
071
071
4007
071
071
4013
4013
4013
4066
4066
071
071
7918
4066
071
072
072
072
072
Op Amp
Op Amp
Op Amp
Op Amp
Quad Two Input NOR
Op Amp
Op Amp
Dual D-Type Latch
Dual D-Type Latch
Dual D-Type Latch
Quad Transmission Gate
Quad Transmission Gate
Op Amp
Op Amp
18V Regulator
Quad Transmission Gate
Op Amp
Dual 071
Dual 071
Dual 071
Dual 071
BC183
BC183
BC183
BC183
BC183
BC183
BC183
BC183
BC413
BC413
BC413
Input Selector Switch
Input Selector Switch
Input Selector Switch
Input Selector Switch
Input Selector Switch
Input Selector Switch
Input Selector Switch
Input Selector Switch
Voltage Selector Switch
Mains
Mains
Switch
Transformer
Stock No.
C47NOZL
C4N70ZM
C100UME
CTNOOJP
C220PJJ
C1NOOJP
C220PJJ
CTKOUTD
C120PJP
C120PJP
CTOOUME
C100UME
C4AN70ZM
caN70ZM
C47NOZL
C47NOZL
C22U0ZE
COSONKA
COSONKA
COSONKA
COSONKA
C100UME
C100UME
CTOOUME
C100UME
DCD4016
DCD4066
DO71CPX
DO71CPX
DO71CPX
DO71CPX
DCD4001
DO71CPX
DO71CPX
DCD4013
DCD4013
DCD4013
DCD4066
DCD4066
DO71CPX
DO71CPX
DUA7918
DCD4066
DO71CPX
DO72CPX
DO72CPX
DO72CPX
DO72CPX
DBC183L
DBCT83L
DBC183L
DBC183L
DBC183L
DBC183L
DBC183L
DBC183L
DBC413X
DBC413X
DBC413X
S44INPA
S44INPA
S44INPA
S44INPA
S44INPA
S44INPA
S441NPA
S44INPA
SVL1869
SFAOFFA
M12727A
Previous
Value
071 OP AMP
071 OP AMP
071 OP AMP
071 OP AMP
Previous
Stock No.
DO71CPX
DO71CPX
DO71CPX
DO7 1 CPX
Comments
Added at ISS 4
Added at ISS 4
See modifications
Added at ISS 5
Added at ISS 5
Added at ISS 5
Added at ISS 5
Added at ISS 5
Added at ISS 5
Added at ISS 5
Added at ISS 5
Removed at ISS 5
Removed at ISS 5
Removed at ISS 5
Removed at ISS 5
Added at ISS 5
Added at ISS 5
Added at ISS 5
Added at ISS 5
Component
Ref.
RV1
RV2
RV3
RV4
SK3
SK4
SKb
SKO
SK7
РСТ
№
FS1
MISC
DONOCHS SON
Volume Pot
Tilt Pot
Bass Pot
Balance Pot
b Pin Din SKT
5 Pin Din SKT
5 Pin Din SKT
Mains Qutlet
4 Pin Din SKT
Mains in SKT
Suppressor
63 Ma Fuse
Front Panel
Chassis
Cover
Sub-Panel
Front Plate
Fuse Holder
Transformer Screen
Transformer Cover
Safety Cover
Voltage Selector Shroud
Mains Switch Link
PC Board Main
PC Board Button
Balance Control Knob
Balance Control Lever
Tone Control Knob
Earth Terminal
Cover Guide
Foot Moulding
Non-Slip Foot
Heatsink T0220
Wire Link for Balance Control
8-Way Cable
10-Way Cable
M2.5 x 6mm Screws Black
M3 x 6mm Screws
M2.5 x bmm Screws
Screw to hold Transformer Cover
Screw to hold Din Sockets to Back
M3 x 6mm Stainless Steel
Grub Screw M3 x 10mm
Grub Screw M3 x 16mm Vol. Control
M4 x 16mm Cover Fixing
M5 x bmm Foot Screw
Serial Number Label
Push On Fix for Sub-Plate
Mains Input Socket Cable Mounting
Mains Interconnecting Lead
5 Pin Din to 4 Phono Lead
4 Pin Din to 4 Pin Din Lead
Sound Deadening
Volume Knob
Led Bezel
Molex Jumper Assy for Disc
Sockets for Plug In Comps
W Button to fix Safety Cover
Warning Label
Clip for Balance Control Linkage
Wire Type 3 Brown
Wire Type 3 Blue
Wire Type 3 Green/Yellow
Washer Shake Proof for Signal Earth Screw
Washer behind Bal. Sleeve
Washers for Bal. Control M2.5 Plain
Washers for Cover Screws M4 Plain
Nut for Regulator Heat Sink M3
Washer M3 x Tmm Thick
Sil Rubber Sleeving for Bal. Link
Nut for Mains Earth Fixing M3
Shakeproof Washer for Mains Earth Fixing
Soldertag for Mains Earth Fixing
Label for QDEFP4A
QUAD 34 service data
Stock No.
R34VOLA
R34TILA
R34BASA
R34BALB
PSOSDNB
PSOSDNB
PSOSDNB
PSP695S
PSO4DNB
PPRO331
NPMR20A
UM63MDA
M12560P
M12567A
M12573A
M12574A
M12570A
PF5234A
M125/1A
M125/2A
M12575A
M12579A
M12771A
112730A
112729A
M12578K
M12578L
M12450P
PQ1124A
M12562A
M12620A
AFNOSLA
NHSTV5A
M12587A
M127118
M12723A
TM206PB
TM306PA
TM205PA
TC406PC
TC205PF
TM306PG
TM310GC
TM316GC
TM416PA
TM405PA
M12734A
FF123ZF
PSRO113
QSPESIA
QD5FP4A
QD4D41A
IPEDAMA
M12586A
M12710A
M12724A
PAM5982
FP70271
M12663A
FF3419A
WM801 31
WM80136
WM8013E
TDB4NLF
M12759A
TDB8NPA
TOM4ASPA
TM3FHPA
TDBENPA
ISFIMS2
TM3FHPA
TDBONLF
FTB65SS5
M12751A
Comments
Replaces 3 Part Switch Link used on early 34's
26
QUAD 34 service data
Component
Ref.
63 RAD Button
64 Disc Button
65 Aux Button
66 CD Button
67 Tape Button
68 Mono Button
69 F1 Button
70 F2 Button
71 SL Button
MOVING COIL INPUT MODULE 100 MICROVOLT
R1a 100R
R2a 100R
Rba 2K2
Вба 2K2
R9a 2K2
R10a 2K2
R21a OR8
R22a 1K1
R23a 6R8
R24a 1K1
Cla 22n
C2a 22n
C12a 47
C13a 47
C14a 47
C15a 47
T1a ZTX750
T2a ZTX650
T3a Z1X750
T4a ZTX650
SK1a Phono Socket
SK2a Phono Socket
MISC
1 PCB
2 Insulating Bush for Phono Socket
3 MZ.5 x bmm Screws
4 M2. 5 Nuts
5 Disc Module Front Plate
6 Disc Module Mounting Bracket
7 Molex Board Plug
8 Packing
9 Packing
10 Wire for Phono
11 Wire for Phono Earth
200 MICROVOLT MOVING COIL INPUT
R1a 100R
R2a 100R
Rba 5K6
Вба 5KO
R9a 5KO
R10a 5K6
R21a 15R
R22a 1K1
R23a 15R
R24a 1K1
C1a 22n
C2a 22n
C12a 22h
C13a 22h
C14a 22h
C15a 2214
T1a ZTX750
T2a Z1X650
T3a ZTX750
T4a Z TX650
SK1a Phono Socket
SK2a Phono Socket
27
Stock No.
MBRADIY
MBDISCY
MBOAUXY
MBOOCDY
MBTAPEY
MBMONOY
MBOOF1B
MBOOF2B
MBOOSLB
R100RJ1
R100RJ1
R2K20G1
R2K20G1
R2K20G1
R2K20G1
ROR80G1
RIK10G1
ROR80GT1
R1K10G1
C22NOJS
C22NOJS
C47UOKT
C47UOKT
C47UOKT
C47UOKT
DZTX75P
DZTX65P
DZTX75P
DZTX65P
PSPHOGS
PSPHOG2
112728A
M12716A
TM205PA
TM2FHPA
M12721A
M12722A
PP50468
ZC34DMI
ZX34DMA
WM60125
WTM71AB
R100RJ1
R100RJ1
R5K60G1
R5K60G1
R5K60G1
R5K60G1
R15ROFN
R1K10G1
R15ROFN
R1K10G1
C22NOJS
C22NOJS
C22UOKB
C22U0KB
C22U0KB
C22U0kB
DZTX75P
DZTX65P
DZTX75P
DZTX65P
PSPHOG9
PSPHOG?
Previous
Stock No.
MBOOF1R
MBOOF2R
MBOOSLR
Comments
Changed at S/N 4130
Changed at S/N 4130
Changed at S/N 4130
Component
Ref.
MISC
—"OODODNOCOUOA AUOUON-—
PC Board
Insulating Bush for Phono Socket
M2.5 x bmm Screws
M2.5 Nuts
Disc Module Front Plate
Disc Module Bracket
Molex Board Plug
Packing
Packing
Wire for Phono
Wire for Phono Earth
400 Microvolt INPUT
R1a
R2a
R5a
Вба
R9a
R10a
R21a
R22a
R23a
R24a
Cla
C2a
C12a
C13a
C1 4a
C1ba
Ta
T2a
T3a
T4a
SK1a
SK2a
MISC
—\ © ©© 00 —1 С) Сл 45 ©) К —
— dh
MOVING MAGNET INPUT MODULE 3 MILLIVOLT
R1b
R2b
atole
R6b
R9b
R1Ob
R21b
R22b
R23b
R24b
C1b
C2b
C12b
C13b
C14b
C15b
T1b
T2b
T3b
T4b
SK1b
SK2b
100R
100R
15K
15K
15K
15K
30R
1K1
30R
TK
22n
22n
104
104
104
104
ZTX750
ZTX650
ZTX750
ZTX650
Phono Socket
Phono Socket
PC Board
Insulating Bush for Phono Socket
M2.5 x bmm Screws
Nuts M2.5
Disc Module Front Plate
Disc Module Bracket
Molex Board Plug
Packing
Packing
Wire for Phono
Wire for Phono Earth
47K
47K
82K
BC214C
BC413
BC214C
BC413
Phono Socket
Phono Socket
QUAD 34 service data
Stock No.
112728A
M12716A
TM205PA
TM2FHPA
M12721A
M12722A
PP50468
ZC34DMI
ZX34DMA
WM60125
WTM71AB
R100RJ1
R100RJ1
R15K0G1
R15K0G1
R15K0G1
R15K0G1
R3OROFN
R1K10G1
R3OROFN
R1K10G1
C22NOJS
C22NOJS
C10U0KT
C10UOKT
C10UOKT
CIOUOKT
DZTX75P
DZTX65P
DZTX75P
DZTX65P
PSPHOG9
PSPHOG2
112728A
M12716A
TM205PA
TM2FHPA
M12721A
M12722A
PP50468
ZC34DMI
ZX34DMA
WM60125
WTM71AB
R47KOJ1
R47K0J1
R82K0J1
R82K0J1
R82KOJ1
R82K0J1
R220RG1
RITORFN
R220RG1
R9TORFN
C220PJJ
C220PJJ
CTUSOKT
C1U50KT
C1U50KT
C1UDBOKT
DBC214C
DBC413X
DBC214C.
DBC413X
PSPHON9
PSPHON2
28
QUAD 34 service data
Component
Ref.
MISC
1 PC Board
2 Insulating Bush for Phono Socket
3 M2.5 x ómm Screws
4 Nuts M2.5
5 Disc Module Front Plate
6 Disc Module Bracket
7 Molex Board Plug
8 Wire for Phono
9 Wire for Phono Earth
29
Stock No.
112728A
M12716A
TM205PA
TM2FHPA
M12721A
M12722A
PP50468
WM60125
WTM71AB
assembly diagram
COB» EWN $
OOOO GO OTOOCOC GTR RBRGS SE BR ARBBUOUQODOUVOUQDODOQOOUONNNNNNNNNN—-—480050500—€0 —À А а
ONOTBRON D DVOODONOOIORONSOOONODOUOBRONSOOUOONOOGUO ФБ (0 № — © ©© 00 = ©) сл [5 (0 о —
Description
Screw M4 x 16 mm
Washer M4
Chassis Guide
Cover
Foot
Screw M4 x 5b mm
Non-Slip Pad
Screw 2Mb x 6 mm
Disc Module
“Earth” Terminal
Screw 27 x 3/16
Fuse TTOOmMA
Fuseholder
Voltage Selector Shroud
Mains Out — Socket
Screw 47 x Va
Mains In — Plug
Mains Transformer Cover
Mains Transformer Screen
Chassis
Screw M3 x 6 mm
Washer M3
Volume Control
Tilt Control
Bass Control
4 Pin Din Socket
5 Pin Din Socket
Screw M3 x 6 mm
8 Way Cable and Socket
PCB Assembled
Safety Cover
WW Button
Screw M3 x 6 mm SS
Button Board Assembled
LED Beze
Push Button Cap — Set
Push-On-Fix
Balance Control
Front Plate
Balance Control Lever
Balance Control Link
Push-On-Fix
Sub-Panel
Balance Control Knob
Mains Switch Link
Screw 2Mb x 5 mm
Washers M2.5
Grubscrew M3 x 16 mm
Volume Control Knob
Grubscrew M3 x 10 mm
Tone Control Knob
Front Panel
Washer M3
Shake Proof Washer 4BA
Soldertag
Nut M3
Warning Label
Washer
Stock No.
TM416PA
TDM4SPA
M12562A
M12573A
M12620A
TM405PA
AFNOSLA
TM206PB
PQ1124A
TC205PF
UMATODA
PF5234A
M12579A
PSR472A
TC406PC
PPRO331
M12572A
M12571A
M12567A
TM306PA
TDM3SPA
R34VOLA
R3ATILA
R34BASA
PSO4DNB
PSO5DNB
TM306PA
M12724A
M12575A
FP70271
TM306PG
M12710A
M12597A
FF123ZF
R34BALA
M12570A
M12578L
M12587A
M12574A
M12578K
M12771A
TM205PA
TDESNPA
TM316HC
M12586A
TM310GC
M12450A
M12560A
- TDBENPA
TDBANLF
FTB6SS5
TM3FHPA
M12663A
M12759A
Fig. 20
QUAD 34 service data
®
30
circuit diagram
M12746 ISS 1
Up to S/N 6000 PCB M12730 ISS 1 and 2
+ 86V
for minor variations see ‘modifications’ os
DI 5608
Swe R4
co 4708
786V
DISC 100»V
C/8 ul
DISC
RADIO
A
Q 3302 N _
са IF a
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100 $ /00K$ 04 Ж,биб Y, DE CVS
mr -
AUX
L CS 330n
i} (7
+ a a
RI22 RI42 07 68 A 09 6V8
/00K < 100K De був 1 DIO 6VE
m
X
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RS C/6 /00u
f © 2k2
R45 КЗ
C30
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C32 In
ARI6 82K
\
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Nerf A AA]
2K2
cs R18 82K
—4 es
OSCAR
Ras (КЗ
R8/ 10M
QUAD 34 servicedata
12
|
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|
15920
bol
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029 RIS
330K
-75v
T2
RIG
JKI
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E = = = . = „АЛ
+ — — —
F7-5V
DISC
e ‘
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( /5920 |025
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12
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R44
034
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+36/ +—e + + + +
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15970 033
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— a o e | —04 + +- + 477 T = a
1707
J
FI#F2 A
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cp *86V
R51 91k REI 9IK PAI ISK ROI 10K
A о’ + + C77 1004
1077 с/о Ln Lo,
C40 RS2 OIK 9/K R64 Cas o |
+ 8.6V | | if
3 3 В 12
СА ASI | RES C46 3 |
в
/n SÓK 56k In R76 39% © R92 22K
68a C57 C75 1120p
R54 820K R66 820k C47
,
+&6V 220n
ASS
680K 27 cas M 4066 |
— Vía VOLUME R37 con Sly 122 |
C32 In C38 3 /OOH 7 |
4 1C12 |
A, 1111
—94V * Rv4a 2
AV3a
BASS
1C20 +86V
R56 9IK R67 QIK R77 ISK RAT К
42 RS7 QIK 9/K R68 C49
+ 8.6V +
53 Mi
C43 R69 C50
Hs
In In REO 39k R94 22K
37 R59 820k R70 820k C53
R46 IK3
220n 220n
К
6
C39 C54
100K 3 6
C33 п 220n 100m
| 4 013
| -94V RV4b
AVI
RI
"2x7
RIZ0 2kK7
leo
S/O
RII 2K2
RI21 2K2
31
circuit diagram
M12746 ISS 2
S/N 6007 to 8000 PCB M12730 ISS 4
for minor variations see ‘modifications’ +50
DI S60R
Sve R4
C/O 4708
|
/
> RSa 2K2
С/2а
|
Tia 47
DISC 100-V 27X750
L
©)
T2a
Pla ZTX650
Ri AI > DJ K6v8 X DS 078
100K>/00K > Di Yovs Y, D6 ove
mm
|+
R122 Ria 07 № був № 09 був
re
x2 |
+ 86V
№15 C/6 10Cu
и «> ANN—
2K2
RAS KI
Ч
Виа |
/
TAPÉ so C32 тп
L
‚ A
\,
L
3
£
R46 КЗ
C33 In
+75V
RES 10M
QUAD 34 service data
029 RS
9
3 Shox
+86 1,
T12
D22 A
RIG
ЗК
5920 |025
у
TS-Tl2 BC183L M -2.4V <
L/
A. cez +
VM18 47n mn s9
+86 e
вю Fs/
/00mA
ES Vv RIO4 L - % р
cse C74 cay NI ;
RIO? 22K = a. 47n
) 7/3 C y <r
TAY £5270
le?
р
A
A ed + / о 4
|| s/0
FIFFE A i
’ | R125 220R
AA ,
R51 OK R63 ЭК R73 ISK ROI ОК
C77 /004 |R117 ARIS 2k2
со | с” у 2K7
220p
+ 8.0V C40 R52 91k 9/K R64 Cas | =
р
/C9 303 UCI7
J 7 |
Car ASI ROS C46 ;
In SOK SÓK in R92 22K
2 68a] С5/ C75 120p
79.4V C36 R54 820K R66 820k C47
C34 Ip 220 +86V 220n {
y RSS
H M2 2 7 cas 4066 | A _
к RVia VOLUME R47 204 6 1cæ
/00K H— |
C32 In C38 3 00K ; X |
4 1012 , |
oh _ 11
—-94/ Rv4a 4
&V3a
BASS
1C20 #86V
RS6 OIK R67 91K R77 ISK ROT 10K
R120 2K7 R121 2K2
IC/8
42 RS7 QIK OK RÓS C49 с
+ 8:6V | |
6 Vy и
|
RV 26 -
C43 RSE две CSO 9
h d
68 CS52
| 7 R59 820K R70 B20K (33
R46 КЗ
22On 220n
R60
co CM. C54
OOK 3 2 i
C33 In 220n y
ho | са
-04y RV46
AYVIO
32
circuit diagram
M12746 ISS 3
From S/N 8001 PCB M12730 ISS 5
. . , , гие . , + 90V
for minor variatrons see modifications
RI
о! 5608
Sve R4
co 4708
‚Оби
R5a 2K2
C/20
\
Fa 47
DISC 100=V 27X750
L
(О)
Tea
Ra ZTX650
47
Cla
1008 22 | Cta
R6a R220
2K2
CH R210 > 147
6.85
"CO R7
De 470R
Sve RE
680R
- 4
L C3 130л
co JOK 680»
JI0n N
Ca +
Ri RI > 03 ve X DS був
/ OOK > Dd YWovo y, De ove
RII CBS
R333 C87
TAPE 39K 6804
L
C32 In
RAS KI
Y 75V
QUAD 34 service data
+7.5v
RIO
JIK
BRON 15920
RIE ray Y 023 107 10M Y
24
cis 12) 173 sl cs 2
Ry 4 СЯ _
ВИЗ ОМ
RING
ЗК
Avia VOLUME
C32 In
A46 /K3
C42
R51 IK
C40 R52 OK
R506 9/K
RS? 9/Ж
(5920 1025
Ÿ J
TS-TI2 BCIO3L M ogy 5
L/
D314
VM/8 572 =
*536Y =—
+75
KG | 074 ce , z
RIO2 22K = 47n N +
10004
— 25 | |
7500 8
có7 |
—04V - 44% T | à
_ 5/0
HCl
FARO A 5
+ 4
R125 2208
АЛИ ——
F2
+8-6V
C19
R63 IK R73 15K ROY OK
Ÿ C77 100 RU7 ANS 2K2
С?О | 'п Де” + 2x7
1017 Zo
91K R64 Cas Г |
' | fi 7
|
12 RIOS › с/т
3 2M2 1
A - Г
Ay AA 017 6
R76 SI R92 22K ‚о
RVda
RVIa
BASS
C20 + вби
267 QIK R77 ISK
NN mm R120 2K7 RI121 2K2
RV4b
REC J9K
ROS 22K
33
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