Leak 2200 Service Manual

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RANK HI-FI
LEAK 2200 AMPLIFIER SERVICE MANUAL

INTRODUCTION

The servicing instructions in the manual are divided into two levels:-

(1) Servicing to module Level, where the fault is located to a module or
major component which can then be replaced.

(2) Complete servicing, where circuit descriptions, circuit diagrams and
test point voltages are provided to assist the qualified service engineer-

CONTENTS

1 . Dismantling the Case

2. Key to Major Components

3. Faultfinding to Module Level

4. Access to Main Amplifier Module
5. Access to Front Panel Components
6. Access to Rear Panel Components

7 . Detailed Servicing

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1 DISMANTLING THE CASE

1a. To remove the top panel:

1b.

Remove the two fixing screws "A" from the back panel. Lift slightly and
remove to rear.

To remove the side panels:

Remove the single fixing screw B" from the back panel, pull the side panel
forward approximately 1 inch and remove to side.

Repeat for the other side.
To remove the bottom plate:

Remove the fixing screws "C" as indicated from the three positions at -
rear of bottom plate, remove bottom plate to rear.

Re-assembly is a direct reversal of these sequences.

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3 FAULTFINDING TO MODULE LEVEL

3.3 DETAIL CHECK PROCEDURES (Cont. . .)

3.3.5

3.3.6

3.3.7

3.3.8

Function Switch and Indicator Check:-

If any of indicators do not illuminate check bulbs. If O.K. check
associated wiring. If O.K. check function selection switch. If for
any selected function there is no output at the speaker sockets check
associated wiring. If O.K. check function selection switch. To
remove function selection switch see Section 5.

Procedure:-

If indicator does not illuminate check bulb. If O.K. check associated
wiring. If O.K. check function selection switch. If no output at speaker
sockets:-

3. Check for signal at input to disc preamp.

b. Check for signal at output from disc preamp.

c . Check for input to function selection switch.

d. Check for output from function selection switch.
If have a. and not b. fault on amplifier module.

To replace amplifier module see Section 4.

If have b. and not c. check associated wiring.

If have 0. and not d. check function selection switch.
To remove function selection switch see Section 5.

Procedure:-

a. Check for input to microphone preamplifier.

b. Check forloutput from microphone preamplifier.

c . Check for input to left channel main amplifier.

If have a. and not b. then fault on microphone preamplifier board.
To replace microphone preamplifier board see Section 6.

If have b. and not c . then fault in associated wiring.

Inject a signal at the input pin of the left channel amplifier such that the
left channel socket output voltage is 10V rms.

Switch the FOUR CHANNEL MATRIX SWITCH TO 0, -1, -2 and -3.

3.. Check that left channel output decreases as follows:-

Matrix Switch Position Socket Output Voltage (rms)
off" 10V: ZdB
0 5v 5 ZdB
-1 2v t 2:13)
_2 1 '5] : ZdB ) if (Sighzakers
-3 0.8V t 2dB ) u p

If above results are not obtained check associated wiring, switch for
correct operation, and the values of attenuation resistors.
To remove switch see Section 5.

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. 7 DETAILED SERVICING

7.5 FRONT PANEL MODULE CIRCUIT DESCRIPTIONS

7. 5.1 Control Amplifier Circuit:-

The appropriate audio signal selected by the Function Selection Switch
(1 .8) is connected to the volume control VRZ. This linear control is
centre-tapped and loaded by El and VRl on the right channel and R2 on
the left channel. These resistors give the control a logarithmic law
and VRZ allows balancing of the channels at half rotation of the volume
control. When 'loudness" is selected at switch bank (1.8) Cl and CZ
are added into circuit to provide bass boost at low volume settings. TRl
in conjunction with C18, R3 and R19 provides impedance transformation
and fixed low frequency roll-off (ldB - 20Hz, 10dB - 10Hz) after which
the signal is fed to the normal Baxendall type feedback tone control.
The amplifier section consists of TR2 and TR3, an emitter coupled NPN
pair connected to TR4 a PNP inverter.
L1, 015 and R14 form a 12dB per octave scratch filter selected by

" "high-filter" at switch bank (1.8). The output from the balance control
V35 goes to CS, right channel and CG left channel on the switch bank (1.8)
which provides a BdB per octave rumble filter selected by low-filter" at
switch bank (1 . 8).

7. 5.2 Control Amplifier Specification:-

Frequenoy Response (t 1 .5dB : ZSHz - 401€Hz
Treble Control ; films at man:
Bass Control : ilsdn at 50Hz
. _ . , -3dB at 5kHZ
High Filter . _10 dB at 10 kHz
. . -3dB at 70Hz
LOW-Filter ' -10d.B at 20Hz

+lOdB at SOHZ
(-40dB volume setting)

Output Impedance : 101(0th nominal

Loudness

7.5.3 Meter Board Circuit:-
The amplifier outputs from the speaker switches (1 .8) are half wave
rectified by the diodes DlR, right channel and DlL, left channel. R1
and Cl smooth the signal and along with R2 and VR1 provide the required
attack and decay times for the meter. Deflection of the meter is
controllable by VRl .
Two fuses F1 and F2 are positioned on the board to protect the indicator
lamps circuitry. The fuse ratings are 2 amp. slow blow.

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