Grundig freaxx 20 Service Manual page 12

GRUNDIG Service
2. Tuner
Measuring instruments: Signal generator, sweep generator, oscilloscope, frequency counter.
Function switch: Radio
Adjustment
1. AM IF Couple in a sweep signal of 465kHz to L506 (ferrite aerial)
via a loop aerial.
Oscilloscope to testpoint TP5 / TP4 (GND).
Band switch: MW
2. MW Oscillator Var. capacitor to limit stop: MW f
Couple in a standard signal to L506 (ferrite aerial) via a
loop aerial, (f
that the signal is just visible).
Oscilloscope to testpoint TP5 / TP4 (GND).
Band switch: MW
3. MW Aerial MW 600kHz, MW 1400kHz
bandpass Couple in a standard signal to L506 (ferrite aerial) via a
loop aerial, (f
that the signal is just visible).
Oscilloscope to testpoint TP5 / TP4 (GND).
Band switch: MW
4. LW Oscillator Var. capacitor to limit stop: f
Couple in a standard signal to L505 (ferrite aerial) via a
loop aerial, (f
that the signal is just visible).
Oscilloscope to testpoint TP5 / TP4 (GND).
Band switch: LW
5. LW Aerial LW 153kHz, LW 261kHz
bandpass Couple in a standard signal to L505 (ferrite aerial) via a
loop aerial, (f
that the signal is just visible).
Oscilloscope to testpoint TP5 / TP4 (GND).
Band switch: LW
6. FM Oscillator Var. capacitor to limit stop: FM f
Couple in a standard signal via a 10nF capacitor to
testpoint TP1 / TP2 (GND) (f
as low as possible so that the signal is just visible).
Oscilloscope to testpoint TP5 / TP4 (GND).
Band switch: FM
7. FM Aerial band- FM 88MHz, FM 106MHz
pass Couple in a standard signal via a 10nF capacitor to
testpoint TP1 / TP2 (GND) (f
as low as possible so that the signal is just visible).
Oscilloscope to testpoint TP5 / TP4 (GND).
Band switch: FM
Preparations
515kHz, f
u o
= 1kHz, m = 30%, U as low as possible so
a
mod
= 1kHz, m = 30%, U as low as possible so
a
mod
292kHz
o
= 1kHz, m = 30%, U as low as possible so
a
mod
= 1kHz, m = 30%, U as low as possible so
mod a
87.35MHz, f
u
= 1kHz, ∆f = 22.5kHz, U
mod
= 1kHz, ∆f = 22.5kHz, U
mod
Adjust to maximum with T501.
1635kHz At f (515kHz) adjust to maximum with L504.
u
At f (1635kHz) adjust to maximum with VCT501(D).
o
Repeat this adjustment alternately.
At 600kHz adjust to maximum with L506 (MW aerial coil,
move).
At 1400kHz adjust to maximum with VCT501(C).
Repeat this adjustment alternately.
At f (292kHz) adjust to maximum with TC501.
o
At 153kHz adjust to maximum with L505 (LW aerial coil,
move).
At 261kHz adjust to maximum with TC502.
Repeat this adjustment alternately.
108.25MHz At f (87.35MHz) adjust to maximum with L503.
o u
At f (108.25MHz) adjust to maximum with VCT501(C).
o
Repeat this adjustment alternately.
a
At 88MHz adjust to maximum with L502 (bend).
At 106MHz adjust to maximum with VCT501(D).
Repeat this adjustment alternately.
a
2 - 4
FREAXX 20 RRCD 4202
Adjustment Process