Adjustment Procedures; Chassis Board - Grundig GV 900 SV/1 Manuel De Service

GV 900..., GV 940...

Adjustment Procedures

GB

1. Chassis Board

Test equipment / aids: Two-channel Oscilloscope with 10:1 Test Probes, Voltmeter, colour generator, test cassette, branded video cassette
Service works on replacement of ...
... the tape drum: Adjustment No. 1, 2
... IC705: Adjustment No. 1, 2; VCR Option Code (page 2-2)
... the tuners or IC1602: Adjustment No. 3, 4
Adjustment
1. Headwheel Oscilloscope: Channel 1 (trigger): ....................... P201-(2)
Position Indicator Channel 2: ................................. Euro-AV1-(19) socket
Play test cassette.
Bridge test points P802 on the chassis board shortly
(activating the test mode). All segments will be indicated on
the display. Subsequently, automatic or manual adjustment
is possible.
2. Tracking Position This adjustment is to be made at the tape speed in
in Slow Motion Standard Play and LongPlay (option) mode.
Mode Feed a CCVS signal into the EURO-AV1 socket and
record it.
Play back this recording in slow motion mode.
Bridge test points P802 on the chassis board shortly
(activating the test mode). All segments will be indicated on
the display.
3. Demodulator Turn R1626 (AGC) counterclockwise to stop position.
Circuit T1601 Feed a standard test pattern (channel 12, aerial signal
(VCO) level 56dBµV) into the warmed up machine.
Voltmeter: .................... P1501-(1) and P1501-(4) – GND
E-to-E mode
4. Tuner control Feed a standard test pattern (channel 12, aerial signal
voltage threshold level 56dBµV) into the warmed up machine.
R1626 (AGC) Voltmeter: .................... P1501-(2) and P1501-(4) – GND
E-to-E mode
GRUNDIG Service
IC1602
1 4
P201
T1601
R1626
VCO
AGC
P1501
1 4
SW813 SW806 SW811
Preparation
P802 P801
SW810 SW807 SW812 SW808 SW809
Adjustment Procedure
• Automatic adjustment: Press Å button. "PLAY" flashes
on the display (at a frequency of about 1Hz) during automatic
adjustment. On successful completion, "PLAY" disappears
from the display.
• Manual adjustment: Use the buttons Ï or Ì to set the
head switching pulse to 6.5 ±0.5 lines before the vertical
sync pulses.
Channel 2:
1V/div 50µs/div
Video output
6.5 ±0.5H (lines)
Channel 1:
2V/div 50µs/div
Head switching pulse
Press button ı to leave the test mode.
Use the buttons C / D to set the picture so that no
disturbances are visible on the screen.
Repeat another section of this recording in slow motion
and correct this setting if necessary.
Press button ı to leave the test mode.
With T1601 (VCO) set the voltage to 2.5V
With R1626 (AGC) set the voltage to 4.3V
Adjustment Procedures
V-sync
±
0.2V.
±
0.2V.
2 - 3