Leak 2000 Service Manual

Page 1

RANK Hi-Fi

LEAK 2000 RECEIVER SERVICE MANUAL

INTRODUCTION
The servicing instruction in the manual is divided into two levels :

(1) Servicing to module level, where the fault is located to a module which can then
be replaced.

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

If further assistance is required please contact :

CONTENTS
1. Dismantling the Case
2. Key to Major Components

Fault Finding to Module Level

3.1

Access to Amplifier and Tuner Modules

4;.

5. Access to Front Panel Components
6, Restringing
7. Audio Section - Service Details

8. Radio Section ~ Service Details

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1 DISMAN'ILING THE CASE.

1a To remove top panel,

Remove fixing screws as shown from
two positions in back panel module.
Lift slightly and remove to rear as
indicated.

1b To remove side panels.

Remove one fixing screw from back
panel module, pull forward and
remove 1.0 side as indicated. Repeat
for other side.

Page 32

Step

6

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A. 31. Section Circuit Description

AM . Tuner

8k

81

The R. F. signal is picked up by the ferrite rod aerial which is tuned by
CH the AM section of the tuner gang. A secondary winding couples this
signal into the '1le base. The appropriate MW or LW coils are selected by
the wave change switch, SW1. TRG is a conventional self-oscillating mixer
with separate oscillator coils for medium and long wave. The oscillator

is tuned by 0T2, a second AM section of the tuner gang. The main winding
of the unused coil is shorted out by the wave change switch.

The IF signal (470kH2 approx ) passes from TRG Via a double tuned trans-
former T1 to TR7. TR7 amplifies the 11 signal and feeds the ceramic filter
X3 which (with 038) provides the main selectivity. X3 feeds TRB which
again amplifies the signal and drives the detector D3 via a fixed tuned
transformer T4. The detector D3 drives the tuning meter via R48, with R49
providing a positive bias so that the centre zero tuning meter is held at the
left of the scale until a signal is received. The negative output from the
detector moves the meter progressively to the centre and then on a strong
signal right across to the right hand side.

The negative detector output, after filtering by C43, L5 and C44, is coupled
via R50 to the AGC time-constant network C42, R45 and then via R40 and T1
to the base of TR7 and R44 to the base of TRB providing reverse AGC.

The audio output is taken via the isolating capacitor C46.

AM Tuner Specification

Frequency ranges :-
long wave : 150 to 350kHz
medium wave 2 510 to 1650kHz
Sensitivity for ZOdB signal/noise : ZOuV
Image rejection : 40dB
l. F. rejection : 40dB at 1MHz
30dB at 220kHz
Selectivity (IHFM) : 25dB
AF bandwidth (-3dB) : 3kHz

A. M. Section Alignment Procedure

AM Generator required set to 30% Modulation at 400Hz, RF level adjusted
as necessary to prevent overload. Generator output coupled via 10K resistor
to AM aerial input (2.5.1).

For all steps requirement is for maximum output at L. Speaker output.

Generator Waveband Tune to: - Adjust :-
Frequency

KHz
470 MW 350kHz Both cores of T1.

550 MW SSOkHZ T2 and then MW aerial
rod.

1400 MW 1400kl-lz CTZ and then CTl
Repeat 2 and 3 until no further improvement can be obtained

150 LW lFiOkllz T3 and then LW aerial rod

350 LW 3:30kllz CB4 and then C24

WW-'11 7! and I} until no lurthci' impi'mrcnuznt can he obtained.