GV 900…, GV 940…
Adjustment Procedures
GRUNDIG Service
2 - 3
k
englisch • English • anglais
GB
Adjustment Procedures
1. Chassis Board
P201
P1501
1
4
P802 P801
R1626
AGC
IC1602
T1601
VCO
SW813 SW806 SW811
SW810 SW807
SW812 SW808 SW809
1
4
SC1503
TU1551
FM from
Tape
V-H.SW
.P
GND PB_CTL_OUT
AFT
RF_AGC
VIDEO_OUT
GND
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
Preparation
Adjustment Procedure
1. Headwheel
Position Indicator
2. Tracking Position
in Slow Motion
Mode
3. Demodulator
Circuit
T1601
(VCO)
4. Tuner control
voltage threshold
R1626 (AGC)
• 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.
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
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
±
0.2V.
With
R1626 (AGC) set the voltage to 4.3V
±
0.2V.
Oscilloscope: Channel 1 (trigger): ....................... P201-(2)
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.
This adjustment is to be made at the tape speed in
Standard Play and LongPlay (option) 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.
Turn R1626 (AGC) counterclockwise to stop position.
Feed a standard test pattern (channel 12, aerial signal
level 56dB
µ
V) into the warmed up machine.
Voltmeter: .................... P1501-(1) and P1501-(4) – GND
E-to-E mode
Feed a standard test pattern (channel 12, aerial signal
level 56dB
µ
V) into the warmed up machine.
Voltmeter: .................... P1501-(2) and P1501-(4) – GND
E-to-E mode
