Dartron D12 Instruction Manual

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INSTRUMENTS

D12 17MHz

DUAL TRACE OSCILLOSCOPE

INSTRUCTION MANUAL

DARTRON INSTRUMENTS LIMITED

PRECISION OSCILLOSCDPESandELECTRONIC INSTRUMENTS

The DARTRON dual trace osci I loscope D12 with its bandwidth from DC-17 MHz at 10mV/cm to 50V/cm, an 2Hz-10 MHz at 1mV/cm is a professional instrument suitable for use in the laboratory, television servicing and the field of higher education . To ensure maximum brightness of the d i sp I ay we have departed from the more conventional monó-accelerator cathode ray tube and ut i I i se i n stead a h i gh performance 5" post -def I ect i on -accelerator (P DA ) cathode ray tube operated at 3.5kV overall. Even so, where additional brightn ess i s required at the highest writing speeds i t i s possible to operate as a single beam oscilloscope, thus effectively dotbling the brightness.

Dual trace operation i s achieved by means of beam switching . The I sewer speeds from 1.5 sec/cm to 2 i 1 I i serf cm are switched i n chopped mode at

200kH z approximately. At sweep speeds between I m i I 1 i sec/cm to 100 rianosec/cm the beam is switched in the alternate sweep mode. The mode of operation i s automat i ca I I y selected by the time base switch and i s always appropriate to the sweep speed.

The instrument may be operated as an X-Y osci I loscope, both channels being independently calibrated over the range 10mV/cm to 50V/cm. The bandwidth. of the X axis is DC-1MHz, and the Y axis is DC-17MHz. Other facilities are available and are described in this manual .

Stabi I ised supplies including both EHT I ides ensures consistency of cal ibrati on for mains variation up to - 10%.

GUARANTEE &SERVICE

The instrument is guaranteed for a period of two years from date of purchase.

An adequate after sales service is available to all users and our Service Department will always be pleased advise either by telephone or in writing. Please quote serial number and date of purchase on all correspondence.

Should it be necessary to return the instrument for servicing please ensure that it is carefully packed in it's original carton to ensure safe transit. We cannot accept responsibi I ity for instruments arriving damaged.

CONTENTS

Page 3

" 5

" 8

" 13

" 17

Specification

Operation

Description of circuit

Maintenance

Parts List

ILLUSTRATIONS

MQ161 — Y amplifier, 60 mV calibrator, beam switching circuit.

MD 164 —Vertical output circuit.

MD163 =trigger circuit, time-base circuit, stabilised± 20V lines, stabilised ± EHT lines.

Fig. 1 —CRT circuit, power supplies interconnection diagram.

Fig. 2 — MD161 component layout, MD

M D 164 component layout.

Fig. 3 — MD163 component layout.

SPECIFICATION

VERTICAL DEFLECTION

Dual trace operation is achieved by beam switching in the chopped or alternate sweep mode.

For sweep speeds from 0.5sec/cm to 2 míllisec/cm operation is in the chopped mode, and in the alternate sweep mode from 1 millisec/cm to 1 microsec/cm. The chop frequency is approximately

200kHz and the appropriate mode is selected automatically by the TIME/CM switch.. Single beam operation is through the Y2 channel, and is useful for obtaining maximum brightness at fast sweep speeds when the trace is expanded X10.

Bandwidth (-3dB)

Sensitivity

Bandwidth

Sensitivity

Accuracy

Input Z

Input coupling

Protection

DC-17MHz and 2Hz-17 MHz Y1 , Y2 and single beam

10mV/cm to 50V/cm in 1 ,2, 5 sequence

2Hz-10MHz - Y 1 in cascade with Y2

1 mV/cm to 5V/cm in 1 ,2, 5 sequence

± 3% for all conditions

1 rr~egoFlm shunted by approximately 30 pF

DC - GND - AC via 50 ohm BNC connector

400V do or peak ac

Horizontal deflection via Y1 channel

Bandwidth (-3dB) DC-1MHz and 2Hz-1MHz horizontal

Sensitivity

Accuracy

10mV/cm to 50 mV/cm in 1 ,2,5 sequence horiz ontal

± 3%

A I I other conditions as for vert i ca I def I ect i on

TIME BASE

The time base may be triggered +ve or -ve internally, externally and externally via Y1 pre-amplifier output X10 applied to the external trigger socket. This latter facility is useful when the external triggering signal is as low as 100mV or as high as 400V. Triggering may be manual only, with no trace in the absence of a triggering signal, or with a bright line display at all sweep speeds in the absence of a triggering signal. A switch provides this option.

Ca I i brat i on

Accuracy

Expansion

Velocity

1 m í crosecon d/cm to 0.5 sec/cm í n 1, 2, 5 sequen ce

± 3%

X10 expansion switch increases time base speed to

100 nanoseconds/cm. Accuracy ± 5%

Continuously variableove~r range of 3 : 1. Reduces lowest time base speed to 1.5 sec/cm

TRIGGER MODES

Internal source

Internal TVF

External sources

Coupling

Level range

Sensitivity 2mm approximately 8Hz to SMHz

5mm " up to 17MHz and higher

In the Y1 in cascade with Y2 mode the sensitivity i s i rriproved by a factor of 10 .

Sensitivity 2cm peak to peak video

Sensitivity 1 V peak to peak 8Hz to 17MHz

100m V to 400 V peak to peak in 1 , 2 , 5 sequence with signal applied via Y1 pre-amplifier X10

AC -AC fast-TVF

Internal greater than 8cm. External greater than 20 volts

AVAILABLE OUTPUTS

Y1 X10

Calibrator

Ramp

Gate

Signals between 2Hz and 12mHz applied to the Y1 channel are available at the BNC output connector amplified X10. Output impedance 50 ohms approximately. Maximum output 5V

60mV peak to peak square wave at line frequency

Accuracy ± 2%

Approximately 10V positive going at sweep frequency

+17V approximately from time base bistable. May be used for probe adjustment

Z MODULATION AC coupled socket available on r'ear panel. 10V produces visible modulation

DISPLAY

SUPPLY

DIMENSIONS

A 5" flat faced post deflection accelerator cathode ray tube operated at 3.5kV overall. DC coupled unblanking completely suppresses flyback re-trace at all sweep speeds, and DC coupled chop transition blanking eliminates background at highest brightness down to lowest sweep speeds

95-111 V, 103-121 V, 111-130V

190-222V, 206-242V, 222-260V

Consumption 30 watts approximately

45-440Hz

16.5cm (6'h") x 31cm (12") x 40cm (15'/z')

We reserve the right to amend the above specification without notice. Any change made will normally be~ improvement resulting from continued development.

OPERATION

SWITCHING ON

Check that the supply transformer is correctly connected to suit the power supply voltage

(see MAINTENANCE section). It is important to fit the correct fuse — 600 m/A for 95-130V and

300 m/A for 190-26-V operation. The instrument is convection cooled and should be operated in a position where external air circulation is not restricted. The power on/off switch is fitted to the

BR I LL control.

OBTAINING A TRACE

(a) Set Y1 and Y2 shift controls to the mid-position between their respective vertical arrows.

(b) Set the X shift control to its mid-position between the horizontal arrow.

(d) Set the TIME/CM switch to 1 msec/cm and TB slide switch 'to X1.

(e) Switch on by rotating BRILL control clockwise from its OFF position. The indicator lamp will light up. Allow a short time for the cathode ray tube to warm up, when two traces shou Id appear on the screen.

(f) Adjust Y1, Y2 and X shift controls for suitable positioning of the displays. Adjust the

BR I LL control for required intensity and the FOCUS control for a sharply defined trace.

Y CHANNEL MODES

The dual trace mode is obtained with the TRIG SOURCE slide switch in the Y1 or Y2 position.

At sweep speeds between .5 sec/cm and 2 msec/cm the vertical amplifiers operate in the chopped mode and are switched at 200kHz approximately. For sweep speeds between 1 msec/cm and

1 usec/cm the alternate sweep mode is employed. The appropriate mode is automatically selected by the T I M E/CNl switch.

Single trace Y2 only operation is obtained with the TRIG SOURCE slide switch in the SB Y2 position. This is useful to obtain maximum brightness at high sweep speeds, particularly when the trace is expanded X10. With the Y1 X10 output connected to the Y2 input a maximum sensitivity of 1 mV/cm is obtained for signals applied to the Y1 input. A co-axial lead should be used for interconnecting the two amplifiers and also to the input connector of Y1 so that hum pick-up is eliminated.

X-Y operation is obtained when the TRIG SOURCE slide switch is also in the SB Y2 position. This is also designated (X). When the TIME/~M switch is set to X-Y horizontal deflection is obtained from signals applied to the Y1 input connector.

Y CHANNEL INPUT COUPLING

The signals applied to the Y1 and Y2 channels are connected to the input attenuators over 3 position slide switches with the following functions:—

(a) DC connection direct to the attenuator.

(b) AC connection to attenuator through 0.1 uF 400V capacitor.

- amplifier grounded. This provides a base line reference at 0 volts.

NOTE: When examining the low amplitude signal superimposed on a high DC voltage the AC coupling should be used. This enables the display to be viewed at high sensitivity settings of the attenuator where otherwise it might not be possible to position the trace on the screen.

TIME BASE

In addition to selecting sweep speeds the TIME/CM switch also determines the mode of dual trace operation, as described above. In the X-Y position the time base is turned off and horizontal

:deflection is obtained from signals applied to Y1 when the TRIG SOURCE switch is in the

SB Y2 (X) position. s

• Sweep speéds from .5 sec/cm to 1 usec/cm are selected by the TIME/CM switch in a 1, 2, ~5 sequence covered by 18 positions. The sweep speeds are correctly calibrated when the TB slide switch is in the

X1 position and the VELOCITY control rotated fully clockwise to its CAL position. Counter-clockwise rotation of_ the VELOCITY control provides continuously variable reduction of sweep speed over a range of 3:1 approximately, thus providing continuous coverage and overlap between sweep speeds.

With the TIME/CM switch in the .5 sec/cm position and the VELOCITY control fully counterclockwise-the slowest sweep speed of 1.5 sec/cm is obtained. With TB slide switch set to X10 the trace is expanded by a factor of 10 and the trace becomes effectively 100 cm in length. With the

TIME/CM switch in the 1 sec/cm position the highest sweep speed of 100 nsec/cm is obtained.

Any portion of the expanded sweep may be viewed on the centre of the screen by operation of the

X shift control.

X-Y MODE

The setting up for this mode of operation is as set out above. It is important that the Y1 and Y2 input couplings should be in the same position, both DC or both AC, as disparate couplings will cause phase shift of the vector display, particularly at low frequencies. The wide bandwidth of the X deflection channel ensures that phase shift is insignificant up to 20 kHz, where it is normally of the order of 0.5 degree. The X shift control positions the trace in the horizontal direction and the

Y2 shift control in the vertical direction. The Y1 shift control is inoperative.

TRIGGER

The time base may be triggered from the internal sources Y1 or Y2 when the trigger mode polarity switch is in the I NT position. With this switch in the EXT position and a signal applied to the external trigger input socket the time base is triggered from the external source. Triggering may be from the positive or negative going slope of the triggering waveform. the option being provided by the trigger mode polarity switch.

When the B/L slide switch is in the OFF position the screen will remain blank in the absence of a triggering signal. With a triggering signal present the LEVEL control may be rotated to select the position on the display at which the time base commences. This mode of operation may be preferable for examining complex waveforms and very low frequency displays, particularly if ripple or noise is present on the signal.

It is expected that normally the B/L ON mode will be used when, with the LEVEL control rotated fully clockwise to the B/L position, a bright reference line will be displayed in the absence of a triggering signal at all sweep speeds. With a triggering signal present the LEVEL control may be operated to obtain a stationary trace triggered at the desired level. If the time base is required to free run continuously the LEVEL.control should be left in the B/L position.

The triggering signal is coupled to the trigger amplifier over filter networks which modify its frequency response so that it becomes suitable for the type of signal being displayed. The filters are selected by a 3 position switch to provide AC, AC fast or TVF modes of operation. Their functions are as follows:—

AC: The trigger circuit bécomes a wideband amplifier suitable for most kinds of signal.

AC fast: The filter rejects low fr-equencies. suitable for triggering high frequencies and complex waveforms, especially when high ripple or noise is present.

TVF: The filter rejects high frequencies and its cut-off is designed to accept frame synchronising signals of a TV video waveform and reject the line frequency component. It is also preferable to use this mode for signals below about 15 Hi.

ADDITIONAL FACILITIES

CAL —

X OUT —

GATE o/p —

Z MOD

Y1 X10

—

This socket provides a DC coupled positive going square wave at line frequency, with an amplitude of 60 mV f 2%.

This provides a vertical deflection of 6 cm when applied to the Y1 or Y2 inputs when the attenuators are set to

10 mV/cm, and enables the calibration ~ be checked.

The attenuator coupling should be in the DC position to avoid slope at the top of the square wave.

This socket is DC coupled to the time base circuit and provides a positive going ramp output of approximately 10 volts.

The output impedance is 15Kohms.

This outlet is connected to the time base bistable to provide a positive going square wave of 17 volts approximately at sweep repetition rate. It should be used for setting up the probe and a protruding pin is fitted for ease of connection.

For this purpose the TIME/CM switch should be set to

1 msec/cm, the Y1 and Y2 couplings to DC and the attenuator to .1 V/cm. The probe capacitor should be adjusted so that a straight horizontal line appears on the screen.

This socket is AC coupled to the grid of the cathode ray tube and is mounted on the rear panel._ An input of 10V produces visible modulation.

Signals applied to Y1 input are amplified X10 and are AC coupled to the Y1 X10 output connector at an output impedance of approximately 50 ohms. Maximum output 5V approximately, bandwidth 2Hz-5mHz.

DESCRIPTION OF CIRCUIT

VERTICAL AMPLIFIERS

The two vertical amplifiers, Y1,and Y2, have identical circuits except that Y1 also contains a

X10 pre-amplifier to provide a 1 mV/cm facility when cascaded into Y2. The following description of the Y1 channeÍ also applies to Y2, the component references in brackets being the complement of thosé in the Y1 channel. The X10 pre-amplifier will be dealt with separately.

Signals from the attenuator are fed to terminal 4 (11) and via the protection circuit R107/C104

(R 168/C119) to the gate of the F ET T R 101 (TR 116) : diodes D 101 /102 (D 107/108) prevent . excessive voltages being applied to the gate. TR101 (TR116) is connected as a source follower and is do coupled to TR105 (TR120). The FET TR102 (TR117) is also connected as a source follower and is coupled via terminal 5 (15) to the trigger channel selector switch S6. TR 104/TR 105

(TR 119/TR 120) are connected in a low gain long tail pair configuration with frequency compensation applied to the emitter. Vertical shift is applied to the base of TR104 (TR119} over the emitter follower TR103 (TR118). The collectors of TR104/TR105 (TR119/TR120) are do connected to the bases of TR110/TR111 (TR112/TR113), the do level being set by R121 (R180). TR110/TR111

(TR112/TR113) are connected as a long tail amplifier with common collector loads R148/R149, the overall gain being set by R147 (R151). Frequency compensation is effected by C113/C114

(C115/C116).

Dual trace operation is obtained by switching the collector circuits of TR110/TR111 (TR112/TR113) over diodes D111 to D114 (D115/D118), the chopped or alternate sweep mode being determined by the•setting of the TIME/CM switch S12. The circuit operates in the chopped mode for sweep speeds up to 2msec/cm and in the alternate sweep mode from 1 msec/cm to 1 usec/cm. The switched outputs from the collectors of TR 110/TR 111 (TR 112/TR 113) are sequentially connected tá the bases of emitter followers TR114/TR115 and, via terminals 7 and 8, to the vertical output amplifier.

The vertical amplifier is assembled on a separate printed circuit board mounted close to the base of the cathode ray tube, its input terminals 19 and 20 being connected to the differential output from the pre-amplifier described above. TR'301/TR302/TR303/TR304 are connected in a long tail pair cascode configuratïon with frequency compensation effected by C302/C303 and C304/R316.

The parallel combination of R301/R302 and R303/R304 provide loads for the collectors of

TR303/TR304 which are do connected to the vertical deflection plates of the cathode ray tube, the overall gain of the complete vertical amplifier system being set to 10mV/cm by adjustment of R313.

The mean do voltage at the collectors of TR303/TR304 is set by R315 to be close to the mean do voltage applied to the horizontal deflection plates to ensure optimum geometry of the display and minimum deflection de-focussing.

X10 PRE-AMPLIFIER

Signals appearing at the source of FET TR301 are do connected to the base of TR106. TR106/TR122 are connected in a long tail pair configuration to provide a single ended output in the correct phase from the collector of TR122 at a do level set by R129. Frequency compensation is provided by

~C106. The collector of TR122 is ac coupled to the BNC connector SKc via the emitter follower

TR108. With signals applied to the input of Y1 and SKc connected to the input of Y2 a sensitivity of 1mV/cm may be obtained. R139 is fed via terminal 9 to the TIME/CM switch S12 and is adjusted to provide a sensitivity of 10mV/cm of horizontal deflection when S12 is in the X-Y position. In this latter condition signals applied to Y1 provide horizontal deflection and those to Y2 tho vertical deflection. s

BEAM SWITCH

TR124/TR125 comprise the beam switch bistable and will operate in three modes as determined by the setting of the TI M E/CM switch S12 and the trigger channel selector switch S6. For sweep speeds

0.5sec/cm to 2msec/cm R200/R205 are grounded over S12 and the circuit becomes astable, switching diodes D111 to D114 and D115 to D118 at 200 kHz approximately. The instrument is now operating in the chopped mode. At sweep speeds above 2msec/cm the operation is in the alternate sweep mode:

R200/R205 are returned to + 20V over S12 and the circuit now becomes bistable. Switching will now occur only at the end of a sweep, when TR123 is turned off by a pulse from the time base circuit.

The switch S6 provides the third mode of operation — Y2 only. In the chopped and alternate sweep modes the collector of TR125 is connected to the collector of TR124 over S6. In the Y2 only position of S6 the collector of TR 125 is open circuited and connected to + 20V.

The output from the beam switching circuit is fed over R196 to D111 to D114 and over R209 to

D115 to D118. When the Y1 channel is being displayed the shunt diodes D111/D114 are turned off and the series diodes D112/D113 conduct, thus connecting the collectors of TR110/TR111 to the emitter followers TR114/TR115 and thence to the vertical output amplifier. The display exists for the duration of a chop or alternate sweep cycle, at the end of which diodes D111/D114 are caused to conduct, raising the cathodes of D112/D113 to a voltage higher than that of their cathodes. The sequence of operations described for the Y1 channel now occur in the Y2 channel, shunt diodes

D117/D118 and series diodes D115/D116 operating in a manner similar to their complements in the

Y1 channel.

TRIGGER CIRCUIT

The trigger polarity switch S9 selects signals from the internal sources Y1 or Y2 over S6, and from an external source over socket SKg. The selected source signal is fed to the trigger amplifier comprising

TR402/TR403/TR404. The output from TR403 is taken to the trigger coupling switch where filtering is introduced so that the circuit will respond to ac, ac fast or TVF signals. S10, the trigger coupling switch, connects trigger signals to the base of either TR405 or TR406 ovér S9, which determines the polarity of the trigger slope. TR405/TR406 are connected as a long tail pair amplifier, and an adjustable bias is applied to the bases from R4 to control the level on the slope waveform at which the time base is triggered. The output from the collector of TR406 is passed to the Schmitt trigger TR407/TR408, where fast edges are developed to trigger the time base bistable

TR409/TR410.

TIIl1E BASE CIRCUIT

The circuitry around TR412/TR413/TR414/D406 develops a constant voltage across the VELOCITY control R3 and R460/R461/R462. The slider of R3 is connected to timing resistors as selected by the TIME/CM switch and a constant current, which is independent of voltage, produces a linear charge in the selected timing capacitor. The time base is calibrated with R3 in the CAL position and this control may be operated to provide a continuous reduction of sweep speed over a ratio of more than

X3:1.

Before the commencement of a sweep TR409 is on and TR410 off, causing TR411 to saturate thus effectively short circuiting the timing capacitor. A negative going pulse from the Schmitt trigger is connected over C407/D401 to the base of TR409, turning it off. TR410 is now turned on and

TR411 turned off, removing the clamp across the timing capacitor which now begins to charge.

The positive going linear ramp voltage thus produced is connected to the horizontal output amplifier over the cascaded emitter follower circuit comprising TR412/TR413/TR414.

As the ramp voltage at the emitter of TR414 rises D404/R446/R447 pass a feedback voltage to D401

to prevent further trigger pulses reaching the base of TR409. To ensure complete freedom from residual trigger breakthrough the Schmitt circuit TR407/TR408 is biassed off by a positive voltage applied to both emitters for the duration of the sweep over TR401/D407. The junction of R446/R447 is connected to the hold-off capacitor as selected by S12, and in the course of a sweep this charges to a positive voltage. The final ramp amplitude at the emitter of TR414 reaches approximately + 10V, at which point feed back from the junction of R449/R450 turns on TR409. The bistable TR409/TR410 now reverts to its original quiescent condition and will accept the next trigger pulse after the hold off capacitor has discharged through R446/R448.

The ramp voltage at the emitter of TR414 is connected over R451 to the output socket SKf. The emitter of TR401 is connected over R457 to the GATE 0/P connector PLa.

BRIGHT LINE CIRCUIT

With the B R I G HT LINE ON/OF F switch S8 closed the screen will remain blank until the arrival of a trigger pulse initiates a sweep: the switch is now in the bright line off position. With S8 open (bright line on) a sweep is automatically initiated in the absence of a trigger signal or one that is too small to actuate the Schmitt trigger. On the arrival of a trigger signal operation of the LEV E L control wil I lock the display at any selected point on the slope of the triggering waveform. The action is as follows: with a trigger signal present the square wave at the collector TR408 is coupled over R452/

C408 to D402, where restoration produces a negative going signal with respect to the negative rail.

The signal now appearing at the emitter of TR419 is integrated by R453/409 and produces a do bias to hold off TR420. The time base is not affected by this condition. In the absence of a trigger signal or one that is too small, the bias is removed. The emitter of TR419 rises and turns on TR420.

R455 is now virtually connected between the negative rail and the cathode of D401, causing the hold off capacitor to be discharged rapidly: TR409 now turns off and a sweep is initiated. At the end of the sweep the charge accumulated on the hold off capacitor is again removed by the action referred to and the cycle is repeated, providing successive sweeps which produce a bright line at all sweep speeds.

HORIZONTAL OUTPUT AMPLIFIER

The ramp or X-Y signal at the emitter of TR414, as selected by the TIME/CM switch S12, is fed over

R432 to the base of TR415. TR415/TR416/TR417/TR418form along tail pair cascode amplifier, with the horizontal shift voltage applied to the base of TR416. Again of X1 or X10 is selected by S7 which introduces R450/R451 (X10) in shunt with R458/R459 (X1) between the emitters of TR415/

TR416. The differential output from the collectors of TR417/TR418 ís do connected to the horizontaF deflection plates of the cathode ray tube over R441 /443.

X-Y MODE

In the X-Y mode the vertical deflection with a sensitivity of 10mV/cm to 50V/cm is provided by the

Y2 channel. With S6 in the (X) position and the TIME/CM switch S12 in the X-Y position the output from the emitter of TR108 is do connected to the input of the horizontal amplifier. In this condition the gain of the horizontal amplifier is automatically set to X10 by contacts on S12, and signals applied to the Y1 channel provide horizontal deflection with a sensitivity of 10mV/cm to 50V/cm. Positioning df the tràce in the horizontal direction is by the horizontal shift control R5, the Y1 shift control being rendered inoperative. In the X-Y mode the time base is stopped b_y removal of the timing circuit and the application of a negative voltage to D401, which causes the cathode ray tube to remain permanently unblanked.

BLANKING

The collector of TR409 is connected to the base of TR423 ovér the emitter follower TR422. In the 7

~ ,,

absence of a sweep and for the duration of the fly back retrace the collector of TR409 is virtually at ground potential and the voltage at the collector of TR423 rises to approximately 120V. This collector potential is connected to the beam blanking electrode of the cathode ray tube; and blanking occurs

With the commencement of a sweep the potential at the collector of TR409 rises to approximately

20V, the collector voltage of TR423 drops to a very low value and the cathode ray tube is unblanked.

Pulses from the beam switch circuit are connected to the base of TR421, the collector of which is connected to the junction of R473 and the base of the emitter follower TR422. This circuit provides do coupled chop transition blanking.

CALIBRATOR

The base currerit of TR126 is de"rived from R217/D127 connected to the + 20V'line. The anode of

D126 is connected to the junction of R217/D127, its cathode being connected to an ac voltage at line frequency via terminal 17. Positive excursions of the ac.voltage saturate TR126 and negative voltages turn it off. The square wave thus produced is fed to the CAL output socket SKd, its amplitude being adjusted to 60mV ± 2% by R215.

POWER SUPPLIES

The power transformer T1 has primary windings to accept síx supply voltages at 45-44Hz. The appropriate connections are shown in the MAINTENANCE section of this manual. All internal power supplies are derived from T1, its secondary providing the following windings:-

6.3V (for c.r.t. heater) 22-0-22V, 150V, 1,000V & 1,200V. .

The 150V supply is rectified by MR1 and after smoothing by C36 and C37 provides approximately

195V do for the collectors of the high voltage transistors feeding the deflection plates of the cathode ray tube.

The 22-0-22V supply is rectified by M R2 and smoothed by C38 and C39 to provide approximately

26V do fot~ the +20V and -20V stabilised lines. Similar circuits are used in both the +20V and -20V lines, and a description of the +20V stabilised line will also apply to the -20V stabilised line. The circuit complements of the latter are given in brackets. The high gain amplifier, comprising TR424/

TR425 (TR427/TR428) compares the reference voltage of the Zener diode D407 (D408) with the voltage at the junction of R481/R482 (R487/R489), a potential divider connected between the emitter of TR426 (TR429) and ground. Any fluctuation of the line voltage at the emitter of TR426 (TR429), which supplies the +20V line, are fed to the báse of TR425 (TR428) and an inverted amplified correction voltage is applied to the base of TR426 (TR429). The voltage drop across R479 (R486) is pruportional to the output current demand at the emitter of TR426 (TR429). Normally this voltage is less than that across R478 (R484), and D411 (D414) is biassed off. If the output current rises beyond the safe maximum D411 (D414) turns on and takes current away from the emitter of

TR424 (TR427). As a result the voltage on the collector of TR425 (TR428)., and the base and emitter of TR426 (TR429), drops, and the current is limited to a safe value. Two further +10V stabilised lines are provided on the vertical amplifier printed circuit board. These are at low impedance, and extremely low ripple content, for feeding the early stages of the vertical amplifiers. ,

Thë -EHT line is obtained from the 1,000V supply and is rectified by MR401 and smoothed by C422 to C425 in series. The do output is taken over R493 to the stabilising Zener diodes D418 to D423 to provide the -EHT line of 1, 068V. The BRI LLiANCE control is across D418 which provides a total swing of 68V, the slider of the control being returned to the grid of the cathode ray tube to control the beam current. Similarly, the FOCUS is taken from an appropriate tapping on the Zener chain, the slider being connected to A2 of the cathode ray tube. The final accelerating potential applied to the PDA terminal is 2.5kV. This is obtained from the voltage doubler circuit C426/C427, MR402/

MR403 and C428/C427, which is fed from the 1,200V supply. The rectified and smoothed do output is connected over R495/R496 to the Zener diode chain D426/D438 to provide a stable + 2.5kV line.

Z MODULATION

Socket SKh on the rear is connected over C40 to the grid of the cathode ray tube. Signals applied to

SKh and its adjacent ground socket SKj produce intensity modulation of the trace.

CATHODE RAY TUBE CIRCUIT

The cathode ray tube and associated circuitry are shown in Fig. 1. The BRI LLIANCE and FOCUS controls are connected as described above. A3 is connected to R211 which is pre-set during test~for minimum astigmatism and optimum focussing over the whole trace. The geometry control R213 is connected to the electrostatic shield between the X and Y plates. R213 is adjusted during test to provide optimum geometry of a test raster. After deflection by the X and Y plates the beam is further accelerated by the 2.5kV applied to the PDA terminal of the cathode ray tube.

MAINTENANCE

REMOVAL OF COVER

Remove two screws from handle shrouds and three screws at the bottom of each side of the cover.

The cover can now be I ifted off.

TRANSFORMER PRIMARY CONNECTIONS

Thè instrument must be disconnected from the supply before making adjustments to the transformer primary. Figure 4 shows connections to be made to suit supply voltages in the range 95 to 260V.

After making adjustments ensure that the correct fuse is fitted. It is important that the fuse be a slow blow type.

CRT REPLACEMENT

Remove bottom cover.

Remove CRT base and PDA cap.

Remove screws from rear of CRT support clip and the clip tightening screw.

Push CRT towards rear of cabinet allowing the support clip to slide along the mu-metal shield. With the CRT fully removed from the front support bezel it can be tilted at an angle and removed through bottom of the cabinet.

Remove mu-metal shield and internal gun shield and fit to the replacement CRT. Be careful nod to knock the mu-metal shield as this may impair its magnetic properties.

Fit CRT support clip, but do not tighten. The CRT can now be put back in position.

Fit clip retaining screws but do not fully tighten. Fit CRT base and PDA cap.

Switch on and rotate CRT so that a horizontal line display is true to the graticule. Fit clip tightening screw and tighten so that it grips the mu-metal shield without distorting it.

Tighten clip retaining screws.

FAULT FINDING

Before attempting to locate a fault it is advisable to check the supply line voltages. The input supply voltage should be approximately at the centre of the range for which the transformer is adjusted.

The voltages are measured with respect to OV (chassis) and are given in Table 1.

LINE

+20V

-20V

+195V

-1060V

+2500V

MEASURED VOLTAGE

+19 to +21 V

-19 to -21 V

+180 to +210V

-1000 to -1120V

+2375 to +2625V

TABLE 1

Table 2 specifies voltages at varíous points on the circuits and may be used as a guide to fault finding.

Wide variations from the voltage indicated may locate a fault condition. in general, all components are accessible without removal of printed circuit boards. If the fault cannot be located the instrument should be returned to the manufacturers or your local service agent for repair. Before making voltage measurements set up the various controls as follows:—

BR I LL, Y1 and Y2 shifts, X shift to mid-position.

TRIG SOURCE slide switch to Y1.

B/L slide switch to ON and LEVEL control clockwise to B/L.

TIME/CM switch to X=Y.

Centre spot on screen with Y1, Y2 and X shift controls.

LOCATION

Emitter of TR109 and TR121

Collector of TR104, TR105, TR119, TR120

Emitter TR108

Col lectors TR 124, T R 125

Collectors TR303, TR305

Collector TR403

Collector TR404

Colléctor TR405

Collector TR408

Col léctor T R419

Collector TR420

Emitter TR414

Emitters TR415, TR416

Collector TR415, TR416

,. TABLE 2

TYPICAL VOLTAGE

+10V (adjustable on R141 and R189)

+ 5.6V

+ 4.6V

+ 13V

+ 100V

+ 17V

+11V

+ 17.5V

+ 20V

- 20V

- 6V

+ 4V

+ 4.5V

+ 100V

STABILITY OF SUPPLY LINES

The stability of the supply lines can be checked by varying the supply input voltage ± 7'/2%around the centre voltage of the primary tapping in use. As an example with the primary connected for operation from 222 to 260V, set up a variable autotransformer to supply 240V ± 1%. With variations of input supply voltage between 222 to 260V the supply lines should not change by more than stated in

Table 3.

LINE

+ 20V

- 20V

+,195V

-1060V

+2500V

TABLE 3

DEVIATION ' not measurable

~ 7'h%approximately

± 1 % "

± 0.5%

SÉTTING UP &CALIBRATION

Test equipment required:

1. Multi-range meter 0 - 3kV at 20,000 o.p.v. .

2. Sine/square wave signal generator 10Hz - 100kHz.

3. Oscilloscope calibrator providing accurate voltage and time calibration signals.

4. TV video waveform generator.

5. Flat top square wave generator 200 - 500kHz providing output of 60mV into

50 ohms. Rise time less than 5nsec.

VERTICAL AMPLIFIERS

Check that a horizontal trace on the CRT is true to the graticule. It is important that the following procedure be carried out in the order specified.

Astigmatism and geometry: display about 10 cycles of a 1 kHz sine wave. I n conjunction with the

FOCUS control adjust R211 for optimum focus over the whole display, which should have an amplitude of about ócm. Adjust R213 for the best compromise between horizontal and vertical pincushioning and barrelling. Re-check the focus and, if necessary, re-set R211

Sensitivity: Switch Y1 and Y2 attenuators to 10mV/cm and from oscilloscope calibrátor apply a

60mV 1 kHz square wave to both channels. Both channels should deflect to exactly ócm. If necessary adjust R147 (Y1) and R151 (Y2) to achieve this result.

Calibrator: Immediately after carrying out the above test apply CAL output to both channels —with input coupling set to DC —and check that deflection is exactly ócm. If not adjust R215 for this result

Attenuator compensation: using a IkHz square wave adjust each step of the attenuators for a display free from overshoot or undershoot. At each step the input signal should be adjusted to give a display of about 5cm. The compensating capacitors of each attenuator have identical layouts —see Fig.1 (c).

SETTING

10mV/cm

20mV/gym

50mV/cm

.1 V/cm

.2V/cm

.5V/cm

1 V/cm

2V/cm

5V/cm

10V/cm

20V/cm

50V/cm

ADJUSTMENT no adjustment adjust C16/C17

" C10/C11

" C32/C33

" C12/C13

" C8/C9

" C26/C27 no adjustment if C12/C13 correct

" adjust C20/C21

" C8/C9 " no adjustment if C12/C13 correct

" " C8/C9 "

Return both attenuators to 10mV/cm and apply 600mV 1 kHz square wave to each channel in turn, via 10:1 probe. With the probe first connected to the Y1 channel adjust the probe compensation capacitor for optimum square wave response. Next fit the probe to the Y2-channel and, if necessary, adjust C118 fór optimum square wave response. If this cannot be achieved carry out the above procedure in reverse order, i.e. setting up the probe first on Y2 channel and adjusting C102 for optimum square wave response from the Y1 channel. Now make the.following adjustments to the input attenuators with 1 kHz square wave applied via probe:—

.1 V/cm

1 V/cm

10V/cm adjust C30/C31

C24/C25

C18/C19 in each case the displayed signal should have an amplitude sufficient to permit accurate adjustment of the compensating capacitors.

Bandwidth: Set TIME/CM switch to 1usec/cm and TB slide switch to X1. Apply output from flat top 5nsec rise time generator, terminated 50 ohms, to the Y1 input with the attenuator set to

10mV/cm. Adjust C113, C303, R316 for optimum square wave response free from ringing and overshoot. It is important that the adjustments be made such that the leading edge is as steep as possible and free from steps. Transfer signal to the Y2 channel and adjust C116 for optimum response.

With both channels still set to 10mV/cm apply to 100kHz sine wave to the Y1 channel and adjust the output from the generator to give exactly ócm of deflection. Note the precise output from the signal generator and re-set the generator to 15mHz with precisely the same output. The resultant display should have a minimum amplitude of 4.2cm, corresponding to -3dB. Repeat the above test for the Y2 channel.

NQTE: a time base setting of 10usec/cm is suitable for the above tests.

TIME BASE CALIBRATION

Set TIME/CM switch to 1 msec/cm and apply accurate 1 msec time markers to the Y1 channel, adjusting the attenuator for a suitable amplitude. Lock signal and adjust F~459 so that each marker is displayeciaccuratelyVat 1cm intervals on the graticule. Set TIME/CM switch to 10usec/cm and time mark generator to 10usec. Adjust C44 for exact spacing of time markers. Check that all other sweep speeds are within stated tolerance.

TIME BASE EXPANSION

Set up a locked display of 1 msec/cm with TB slide switch in X1 position. Now switch TB slide switch to X10 and apply 10msec time markers to the Y1 input. Adjust R451 so that the signal is accurately displayed at 1 cm intervals on the graticule.

TRIGGER SENSITIVITY

(1)• With trigger coupling switch in AC position apply a 10Hz sine wave signal to the Y1 input and check that the display can be locked by the LEVEL control down to an amplitude of 2mm approximately in both the B/L ON and B/L OFF conditions.

(2) Apply a SmHz signal with an amplitude of 2mm approximately and check that the display can be locked as in (1) above.

(3) Carry out the test as in above but with an amplitude of 5mm approximately. Increase the input frequency to 15mHz and check that the display can be locked.

(4) Switch to AC fast and apply a 10kHz signal to give a 5mm deflection. Check that it is difficult to lock this signal.

(5) Switch to TVF and apply a signal from the video waveform generator with an amplitude of about 2cm. Check that the LEVEL contról can be adjusted to give a stable display triggered from the video frame pulse.

(6) Apply an external trigger signal and check that it can be locked from a 1 V input over the range 10,Hz to 15mHz.

X-Y OPERATION

Set up the instrument for X-Y operation and apply the 60mV CAL signal to the Y1 input with input coupling set to DC. Set the Y2 input coupling to the ground position. .Check thát the two spots span ócm exactly in the horizontal direction: if not adjust R139 for this result. Remove CAL signal and apply a 10kHz sine wave to produce a horizontal line of exactly ócm. Note the precise output from the signal generator and rë-set to 1 mHz with exactly the same output. The resulting line should not be less than 4.2cm in length. This indicates a 1 mHz bandwidth -3dB. A lire in excess of 4.2cm indicates a still higher bandwidth.

Z MODULATION

Set Y1 attenuator to 5V/cm,-Y2 input coupling to ground position and TIME/CM switch to 1msec/cm.

Apply a 10V 1 kHz square wave to Y1 output and Z modulation socket at rear of instrument. Lock the Y1 display and then shift off the screen. Centre the Y2 display and check that the resultant horizontal line is adequately blanked at normal brilliance levels.

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,~ c--~

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,--

PARTS LIST

COMPONENT SPECIFICATIONS.

All resistors carbon film ±

5% 1/3 watt, unless specified. All capacitors paper, ceramic or polystyrene minimum working voltage 50V do unless specified. All transistors as specified, except that suitable alternatives may be used in some instruments. All Zener diodes 300 milli-watts minimum, unless specified.

X Board MD 163

R401 47K

R402 10K

R403 1 K

R404 47R

R405 4K7

R406 100R

R407~ 10R

R408 100K

R 409 100 R

R410 6K8

R411 120R

R412 100K 2 watts

R413 330R

R414 10R

R415 1 K

R416 4K7

R417 1 K2

R418 1 K2

R419 47R

R420 47 R

R421 270R

R422 1 K5

R423 4K7

R424 3K3

R425 1 K

R426 68K

R427 47 R

R428

R429

10K

2K7

R430 1 K2

R431 39K

R432 100R

R433 1 K8

R434 1 K8

R435 2K ± 2%

R438 100R

R439 1 K8 ,

R440 10K 2 watt

R441 100R

R442 10K 2 watt

R443 100R

R444 56K 1 watt

R445 56K 1 watt

R446 1 K

R447 1 K

R448 27 K

R449 15K

R450 100R

R451 100R pre-set

R452 10K

R453 1 M5

R454 1 K

R455 10K

R456 10R

R457 10K

R458 1 K8

R459 1 K pre-set

R460 56K 1 watt

R461 2M2

R462 3K9

R463 1 K2

R464 27 R

R465' 3K3

R466 100K

R467 1 K8

R468 12K

R 469 47 K

R470 3K9

R471 3K9

R472 560R

R473

R474

R486

R487

10 R

10R

R475 22K

R476 15K

R477 15K 2 watts

R478 82R

R479 5R6

R480 47K

R481 2K2

R482 1 K3

R483 , 10R

R484 82 R

R485 47K

5R6 r

2K2

R488 100R' ~

R489 1 K3

R490 10R

R491 47 K

R492 47 K

R493 120K 1 watt

R494 33K

R495 3M3 1 watt

R496 100K

R497 100R

R498 ~ 27K

R499 100K

R 500 680

NOTE: R451 was 470R and R472 was 100R on some models.

C401 .01 u F

C402 680 p F

C403 .1 u F

C404 10 uF 25V Elect.

C405 22 uF 25V Elect.

C406 33 p F

C407 6. 8 p F

C408 .01 uF

C409 10 uF 10V Tantatum

C410 220 p F

C411 .01 u F

C412 .1 uF

C413 .1 uF

C414 .01 u F

C415 33 pF

C416 .01 u F

C417 .01 uF

C418 33 pF

C419 27 pF

C420 22 p F

C421 180 pF

C422 2.2 u F 450V E I ect.

C423 • 2.2 uF 450V Elect.

C424 2.2 uF 450V Elect.

C425- 2.2 uF 450V Elect,

C426 .02 u F 1.5kV

C427 .02 u F 1.5kV

X Board MD 163co~v.

C428 4700 p F 4kV

C429 4700 pF 4kV

C430 1 uF 35V Tantalum

C431 .01 u F

C432 6.8 pF

C433 .01 u F

D401 1 N4148

D402 11V4148

D403 1N4148

D404 1 N4148

D405 10V Zener

D406 7.5V Zener

D407 1 N4148

D408 6.8V Zener

D409 1 N4148

D410 1N4148

D411 1 N4148

D412 1 N4148

D413 1N4148

D414 1 N4148

D415 1 N4148

D416 1 N4148

D417 1N4148

D418 68V Zener 1 watt

D419 200V Zener 1 watt

D420 200V Zener 1 watt

D421 200V Zener 1 watt

D422 200V Zener 1 watt

D423 200V Zener 1 watt

D424 1N4148

D425 1 N4148

D426 200V Zener 1 watt

D427 200V Zener 1 watt

D428 200V Zener 1 watt

D429 200V Zener 1 watt

D430 200V Zener 1 watt

D431 200V Zener 1 watt

D432 ~200V Zener 1 watt

D433 200V Zener 1 watt

D434 200V Zener 1 watt

D435

D436

D437

D438

200V Zener 1 watt

MR401 MR250 *

M R402 M R 250 *

M R403 M R250 *

* suitable alternatives may be used.

TR401 BSX20

TR402 BSX20

TR403 BSX20

TR404 BSX20

TR405 BSX20

TR406 BSX20

TR407 BSX20

TR408 BSX20

TR409 BSX20

TR410 BSX20

TR411 BSX20

TR412 BC212

TR413 BC212

TR414 BC182

TR415 BC212

TR416 BC212

TR417 BF258

TR418 BF258

TR419 BC212

TR420 BC182

TR421 BSX20

TR422 BSX20

TR423 B F258

TR424 BC212

TR425 BC182

TR426 BC301

TR427 BC182

TR428 BC212

TR429 BC303

X Board MD163 completely assembled our Part No. MD163C

Y1 Attenuator

R22

R24

R26

R28

R30

R32

R43

R 14

R 16

500K ± 1%

1 M± 1%

R 18 • 800 K± 1%

R20 250K ± 1%

900K ± 1%

111 K± 1%

990K ± 1 %

10K1 ± 1%

1M± 1%

1K± 1%

10R

C10

C12

C14

3-10 pF

4-20 pF

6.8 pF

C16

C18

C20

• C22

C24

C26

C28

C30

C32

C34

6-25 pF

4=20 pF

3-10 pF

39 pF

4-20 pF

1000 pF

4-20 pF

3-1C pF

.01 uF

Y2 Attenuator

R 15

R 17

R19

R21

R23

R25

R27

R29

R31

R33

R45 10R

500K fi 1%

1 M± 1%

800K± 1%

250K ± 1%

900K ± 1%

111 K± 1%

990K ± 1%

10K 1± 1%

1 M± 1%

1K± 1%

C11

C13

C15

' C17

C19

C21

C23

3-10 pF

4-20 pF

6.8 pF

6-25 pF

4-20 pF

3-10 pF

39 p F

C25

C27

C29

C31

4-20 pF

10Q0 pF

4-20 p F

C33

C35

3-10 p F

.01 u F

Y1 or Y2 attenuator completely assembled MD 162C

Frontpanel components

1K Y1 shift

1 K Y2 shift

5K Velocity

100K Level

R5 . , 5K X shift

1 M Focus

250K Brill +S2

~ ~ r

.~,

..~

--,

R 8

R 10

R11

R 12

R12

22K *

22K * l n Y 1 atten.

In Y2 atten.

100K 2W **

4K7 **

1N4148

1 N4148

1 N4148 * ~.

* were 27 K on some models.

** now mounted on

X Board M D 163 as

R412, R416 and

D416, D417, D424, D425

560 p F

1 uF Tantalum

6.8 pF *

.01 u F

.1 u F 400V

* now on X board

M D 163 as C432

N 1 120V neon

Rear panel components

R34 1M

R35 1 K5 2W

R36

R46

1K 1W

100K

--,

~ c

C36

C37

C38

C39

C40

M R 1

M R2

FS 1

100 u F 275V

200 u F 275V

1000 u F 50V

.02 1.5kV

W006 *

W004 *

300 mA or 600 mA slow blow fuse

T1 TR/D12

* mounted on T1

Time/cm switch

C41 1 uF ± 1%

' C42 .01 uF± 1%

C43 68 pF

C44

C45

6-25 pF

4.7 u F

C46 .047 u F

C47 560 pF

C48 560 pF

R37

R38

R39

R40

R41

R40

100K ± 1%

100K ± 1 %

300K ± 1 %

500K ± 1 %

1M ± 1%

3M ± 1 %

10K

D5 1 N4148

Switch completely assembled our

Part TB/D 12

YBoardMD161

R 101 8k2

R102 4k7 pre-set

R103 2K7

R104 100R

R105 10R

R 106 ±

R 107 330K

R108 47 R

R109 15K

R110 10R

R111 6K8

R112 10R

R113 3K9

R114 10R

R115 10R

R116 470R

R117 1K8

R118 470 R

R119 470R

R120 47 R

R121 4K7 pre-set

R122 4K7

R123 100 R

R124 100R

R 125 2K7

R126 180R

R 127 4K7 pre-set

R128 100 R

R 129 4K7 pre-set

R130 1K2

R131 10R

R 132 2K4

R 133 10R

R 142

R 143

R144

R145

R146

R147

R148

R149

R 134

F~ 135

R 136

R137

R138

R139

R 140'

R141

2K7

1 K pre-set

390R

10R

4K7 pre-set

10R

10K pre-set

10R

8K2

330 R

180R

500R pre-set

2K7

R150

R151

180R

500 R pre-set

R152 330R

R153 330 R

R154 8K2

R155 10R

R 156 10R

R157 10R

R158

R159

R 160

R161

10R

4K7

R162 4K7

R163 4K7 pre-set

R164 8K2

R165 10R

R166 2K7

R167 1M ± 1%

R168 330K

R169 10R

R170 47 R

R171 10R

R172 15K

R173 15K

R 174 10R

R175 3K9

R176 10R

R177 10R

R 178 10R

R179 4K7

R180 4K7 pre-set

R181

R182

470R

470 R

R183 470 R

R184 47 R

R 185 1 K8

R186 10R

R187 10R

R188 6K8

R189 10K pre-set

R190 10R

R191 10K

R192 100K

R193 10R

R194 15K

R195 2K7

R196 180R

R197 18K

R 198 4K7 pre-set

R199 10K

R200 18K

R201 82K

R202 2K7

R203 82K

R204 8K2

R 205 18K

R206 18K

R207 15K

• R208 18K

180 R

R 209

R210 10R

R211 100K pre-set

R212 5K6

R213 100K pre-set

R214 5K6

R215 10 K pre-set

R216 6K8

R217 100K

R218 5K6

R219 100K.

R220 100K

R221 10K

R222 1008

R223 100R

R 224 S.O.T.

R225 S.O.T.

R226 100R

R227 47 R

~~.O.T. = selected on test

C101 10 u F 25V

C1Ó2 3-10 pF

C103 .01 u F

C104 .01 u F 400V

C105 39~ p F

C 106 S.O.T.

C 107 39 pF

C108 .01 u F

C109 ï 0 u F 25V

C110 1 uF 35V "Tantalum

C111 T 22 u F 25V

C1'12 .01 u F

C113 6-60 p F

C114 68pF•

C115 68 pF

C116 6-60 p F

C117 .01 u F

C118 3-10 pF

C119 .01 u F

C120 10 u F 25V

C121 . .01 u F

C122 22 uF 25V

C123 39 pF

C124 .01 uF

C125 10 u F 25V

C126 .01 u F

C127 56 p F

C128 .01 uF

C129 56 p F

C130 18 pF

C131 18 pF

C132 56 pF

C133 1000 p F

C134 .01 uF

D101 1 N4148

D102 1 N4148

D103 6.8V Zener

D104 6.8V Zener

D°105 15V Zener

D 106 15V Zener

D107 1 N4148

D108 1N4148

D109 not used

D110 6.8V Zener

D111 1 N4148 ;

D112 1 N4148

D113 1 N4148

D114 1N4148

D115 1 N4148

D116 1 N4148

D117 1 N4148

D118 1 N4148

D119

D 120

1 N4148

D121 1 N4148

D122 6.8V Zener

D 123 1 N4148

D 124 1 N3595

D125 1 N3595

D 126 1N4148

D 127 1 N4148

TR 101 2N3819

T R 102 2N3819

TR 103 BSX20

T R 104 BSX20

TR 105 BSX20

TR 106 BSX20

TR 107 BSX20

TR 108 BSX20

TR 109 BSX20

TR110 BSX20

TR111 BSX20

TR112 BSX20

TR 113 BSX20

TR 114 BSX20

TR115 BSX20

TR116 2N3819

TR117 2N3819

TR118 BSX20

TR119 BSX20

TR 120 BSX20

TR121 BSX20

TR 122 BSX20

TR 123 BC212

T R 124 BCY71

TR 125 BCY71

TR 126 BSX20

Y Board MD161 completely assembled our Part. No. MD 161 C

Vertical output board MD 164

R301 5K6 '2W

R 302 3 K3 2W M

R303 5 K6 2UÏ!

R304 3K3 2W

R305 47 R

R306 10R

R307 10R

R308 39K

R309 220 R

R310 220 R

, R311 39K

R312 220R

R313 22K preyset

R312 100R

R315 100R pre-set

R316 100R pre-set

C301 .01 u F

C302 .068 u F

C303 6-60 p F

C304 180 pF

D301 1 N4148

D302 1 N4148

TR301 • 'BSX20

TR302 BSX20

TR303 B F380

TR304 B F380

Vertical output Board

MD164 completely assembled our

Part No. MD164C

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