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T 22
©
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 to aerial socket.
Level 300µV / 75Ω.
Digitalvoltmeter to testpoint F .
4. Station search
FM, 98MHz
Test generator 98MHz to aerial socket.
Level 100µV / 75Ω.
Digitalvoltmeter 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
Digitalvoltmeter 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.
GRUNDIG Service
Preperation
D
D
D (Pin 4).
D
= 38kHz.
mod
= 19kHz.
mod
= 1kHz.
mod
Abgleichvorschriften / Adjustment Procedures
Adjustment Procedure
Adjust F1 a to maximum and symmetry.
Adjust F7 i to K
(typ. 0.12%, max. 0.2%).
min
Adjust R 119 F to 1.5V + 0.05V.
Adjust R 123 S to 1.2V + 0.05V.
Adjust R 69 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 alternating,
end with 1449kHz.
at
III
2 - 2
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