Service manual

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3 - 2 GRUNDIG Service
Adjustment Procedures GV 30…, GV 50…
GB
Adjustment Procedures
Chassis Board
View of Solder Side
TP182
TP183
IC301
R3031
TN-3
VR631
Test equipment / aids: Two-channel oscilloscope, 10:1 probes, voltmeter, colour generator, test cassette, branded video cassette
Service works on replacement of …
… the tape drum: Adjustment No. 1, 2
… IC305: Adjustment No. 1, 2
… Tuner/Modulator: Adjustment No. 3
Adjustment Preparation Adjustment Procedure
1. Headwheel
Position Indicator
2. Still Picture
Optimisation
3. Stereo Decoder
TN-3:
Crosstalk VR631
• Automatic adjustment: The adjustment process is
indicated on the display. The meter counts from "P: 0:01"
to maximum "P: 2:55". The meter will stop at the set value.
The value can then be adjusted manually.
• Manual adjustment: Use the buttons Ü or * to set the
head switching pulse to 6.5 ≥ 0.5 lines before the vertical
sync pulses.
6.5 –0.5H (lines)
V-sync
Channel 1:
2V/div 50 s/div
Head switching pulse
Channel 2:
1V/div 50 s/div
Video output
Press button Ł to leave the test mode. The indication
"P:– : –" appears for a short time on the display.
With buttons C / D set the still picture according to your
best personal impression.
With VR631 (stereo decoder TN-3) adjust for minimum
amplitude.
Oscilloscope:
Channel 1 (trigger): ................................................ TP183
Channel 2: ..................................... Euro-AV1-(19) socket
Test cassette, playback
When the playback picture appears touch the K button
three times immediately. The automatic adjustment mode
will start.
Feed a CCVS signal into the EURO-AV1 socket and
record it in Standardplay mode.
Play back this recording and press button Ó .
Feed in a standard test pattern with "Stereo" sound modulation.
– right channel 1kHz, 30% modulated
– left channel not modulated
Oscilloscope: ................................ EURO-AV socket Pin 3
Press the "Audio" button on the remote control so often as
is necessary to make "L R" appear in the display.