Adjustment Procedures - Grundig RCD 400 Serviceanleitung

Ableichvorschriften / Alignment Procedure
GB

Adjustment Procedures

Test Equipment:
Sweep generator, Test generator, Stereo coder, AF generator, Oscilloscope, Digital voltmeter, AF voltmeter, Distortion meter
Note:
The frontend is a completely preadjusted module. Only the IF filter must be adjusted to the IF amplifier (1). The values of the tuning voltages are:
87.5MHz = typ. 1.6V min 1.3V
108MHz = typ. 8.0V max 9V
Adjustment
1. IF Filter FM, 98MHz.
Sweep generator 98MHz to aerial socket. Level approx.
100µV / 75Ω.
Oscilloscope to testpoint B .
2. Demodulator FM, 98MHz
Test generator 98MHz to aerial socket. Level approx.
100µV / 75Ω, ∆f = ±40kHz.
Distortion meter to AF output.
3. Field strength FM, 98MHz.
indication Test generator 98MHz, U
Digital voltmeter to testpoint F .
4. Station search FM, 98MHz.
Test generator 98MHz, U
Digital voltmeter to testpoint G .
5. Stereo Crosstalk FM
Stereocoder, left channel modulated, to aerial socket.
AF voltmeter to AF output, right channel.
6. Adjacent channel FM
AF generator 114kHz, approx. 100mV to the input of F2 D
filter
(Pin 2).
AF voltmeter to the output of F2 D
7. 38 kHz Filter FM
Test generator to aerial socket; FM, f
AF voltmeter to AF output.
8. 19 kHz Filter Test generator to aerial socket; FM, f
AF voltmeter to AF output.
9. MW Oscillator MW, 531kHz
Digital voltmeter to testpoint E .
10. MW RF Circuits MW
Test generator via 120-150µH parallel to frame aerial; AM,
U = 3µV, m = 30%, f
RF
AF voltmeter to AF output.
2 - 2
Preperation
= 300µV / 75Ω to aerial socket.
RF
= 100µV / 75Ω to aerial socket.
RF
D (Pin 4). D D D
= 38kHz.
mod
= 19kHz.
mod
= 1kHz.
mod
Adjustment Procedure
Adjust F1 a to maximum and symmetry.
Adjust F7 i to K
(typ. 0.12%, max. 0.2%).
min
Adjust R119 F to 1.5 V + 0.05V.
Adjust R123 S to 1.2V + 0.05V.
Adjust R69 C to minimum.
Control the left AF output with modulated right channel.
Adjust F2 D to minimum.
Adjust F9 J (left channel) and F11 K (right channel) to
minimum.
Adjust F9 G (left channel) and F11 H (right channel) to
minimum.
Adjust L18 to 1.1V.
VI
Adjust C3 and F6 at 1449kHz and L1
IV VII
558kHz to maximum. Repeat the adjustment reciprocally,
end with 1449kHz.
RCD 400
at
III
GRUNDIG Service