Grundig M 49-DPL, Руководство по обслуживанию

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2 - 4 GRUNDIG Service
Abgleichvorschriften / Adjustment Procedures M 49-DPL
GB
Adjustment Procedures
1. Tuner
Measuring instruments:
Standard/sweep signal generator, stereo coder, oscilloscope, distortion meter, DC voltmeter, AF voltmeter, audio signal generator
Service works after replacing the front end: Alignment no. 2
The frontend is a completely adjusted module. Only the IF filter is to be tuned to the IF amplifier.
Alignment Preparation Procedure
1. FM Oscillator
2. FM IF
3. FM Demodulator
4. Stereo Crosstalk
5. Adjacent channel
filter
6. MW Oscillator
7. LW Oscillator
8. AM IF
9. MW aerial
bandpass circuit
(MW RF)
10. LW aerial
bandpass circuit
(LW RF)
11. AF reject circuits
FM
DC voltmeter to Frontend Pin 5 (VT).
FM, 98MHz
Sweep generator 98MHz to aerial input.
Level about 100
µ
V/40dB
µ
V/75
Ω
, f
mod
= 1kHz, dev. 22.5kHz.
Distortion meter to Loudspeaker output.
FM
Signal generator 10.7MHz to aerial input.
f
mod
= 1kHz, deviation 22.5kHz.
AF voltmeter or oscilloscope to Loudspeaker output.
FM, 98MHz
Stereo coder, left channel modulated to aerial input.
98MHz, pilot tone, f
mod
= 1kHz, deviation 40kHz.
AF voltmeter to Loudspeaker output of right channel.
System off
Connect audio signal generator 114kHz, 100mV via a ca.
40nF capacitor to IC301 (Pin 8).
Connect AF voltmeter via a ca. 40nF capacitor to IC301 (Pin 9).
MW
DC voltmeter to Frontend Pin 5 (VT).
LW
DC voltmeter to Frontend Pin 5 (VT).
MW
Sweep generator 450kHz to aerial inputs.
U
out
as low as possible, m = 30%, f
mod
= 1kHz.
AF voltmeter or oscilloscope to Loudspeaker output.
MW
Signal generator to aerial inputs.
U
out
as low as possible, m = 30%, f
mod
= 1kHz.
AF voltmeter or oscilloscope to Loudspeaker output.
LW
Signal generator to aerial inputs.
U
out
as low as possible, m = 30%, f
mod
= 1kHz.
AF voltmeter or oscilloscope to Loudspeaker output.
FM, 98MHz
Signal generator to aerial socket.
Level about 100
µ
V/40dB
µ
V/75
Ω
, f
mod
= 19kHz.
AF voltmeter to Loudspeaker outputs.
Check at 108.0MHz for 8V
±
0.3V.
With IF Filter (inside of Frontend) set for minimum
distortion.
With IFT304 set for maximum.
With VR302 set for minimum.
Control the left AF output with modulated right channel.
With IFT303 set for minimum.
With IFT300 set to 8.0V
±
0.3V at 1620kHz.
With IFT301 set to 7.0V
±
0.3V at 290kHz.
With IFT302 set for maximum.
With IFT305 set for maximum at 558kHz.
With C429 set for maximum at 1440kHz.
Repeat alignments.
With IFT306 set for maximum at 160kHz.
With C428 set for maximum at 280kHz.
Repeat alignments alternately.
Align with LPF301 at the right channel, resp. with LPF300
at the left channel for minimum.
IF (MHz) IF Filter IF Filter
Ident letter Colour
10.6500 D black
10.6750 B blue
10.7000 A red
10.7250 C orange
10.7500 E white
When replacing one of the ceramic
resonators, take care that the colour code
of all resonators is the same.