Grundig RR 740 CD Bedienungsanleitung Seite 17

RR 740 CD / RR 770 CD
3. Tuner
Measuring instruments: Signal generator, Sweep generator, Oscilloscope, Digital voltmeter.
Function switch: Radio
Adjustment
1. AM IF Couple in a sweep signal of 450kHz to L503 (ferrite aerial)
via a loop aerial.
Oscilloscope to testpoint
Band switch: MW
2. MW Oscillator MW, 1620kHz
Digital voltmeter to testpoint
Band switch: MW
3. MW Aerial MW 612kHz, MW 1404kHz
bandpass Couple in a standard signal to L503 (ferrite aerial) via a
loop aerial, (f
that the signal is just visible).
Oscilloscope to the headphone socket.
Band switch: MW
4. LW Oscillator LW, 281kHz
Digital voltmeter to testpoint
Band switch: LW
5. LW Aerial LW 164kHz, LW 272kHz
bandpass Couple in a standard signal to L504 (ferrite aerial) via a
loop aerial, (f
that the signal is just visible).
Oscilloscope to the headphone socket.
Band switch: LW
6. FM IF FM 10.7MHz
Couple in a sweep signal via a 10nF capacitor to testpoint
TP 1
Oscilloscope to testpoint
Band switch: FM
7. FM Oscillator FM, 108MHz
Digital voltmeter to testpoint
Band switch: FM
8. FM Aerial FM 90MHz, FM 106MHz
bandpass Couple in a standard signal via a 10nF capacitor to
testpoint
U as low as possible so that the signal is just visible).
a
Oscilloscope to the headphone socket.
Band switch: FM
GRUNDIG Service
Preparations
(IC502 Pin 18).
TP 5
(CN501 Pin 9).
TP 6
= 1kHz, m = 30%, U as low as possible so
a
mod
(CN501 Pin 9).
TP 6
= 1kHz, m = 30%, U as low as possible so
mod a
/ (GND).
TP 2
(IC502 Pin 19).
TP 4
(CN501 Pin 8).
TP 7
= 1kHz, ∆f = 22.5kHz,
/ (GND) (f
TP 1 TP 2
mod
62
62
62 $
'
&
62 %
Abgleichvorschriften / Adjustment Procedures
Adjustment Process
Adjust to maximum with T502.
±
At 1620kHz adjust to 8.2V 0.1V with L505.
At 612kHz adjust to maximum with L503 (MW aerial coil,
move).
At 1404kHz adjust to maximum with TC502.
Repeat this adjustment alternately.
±
At 281kHz adjust to 7.9V 0.1V with L506.
At 164kHz adjust to maximum with L504 (LW aerial coil,
move).
At 272kHz adjust to maximum with TC503.
Repeat this adjustment alternately.
Adjust to maximum and symmetrical
response with T501.
Adjust to symmetrical response
centered with T503.
Repeat this adjustment alternately.
±
At 108MHz adjust to 7.9V 0.1V with L502 (bend).
At 90MHz adjust to maximum with L501 (bend).
At 106MHz adjust to maximum with TC501.
Repeat this adjustment alternately.
Tuner Board
62 !
S-Kurve
S Curve
62 #
62 "
2 - 5