GV470S…
Abgleichvorschriften / Adjustment Procedures
GRUNDIG Servicetechnik
3 - 9
3. S-VHS Board
Service work after replacing the Family Board
– 3.1 Luminance ................................................... Adjustment no. 6
3.1 S-VHS Board – Luminance (SH)
Test Equipment: Oscilloscope, 10:1 Test Probe, Frequency Counter, Digital Voltmeter, Stabilized Power Supply, Colour Generator, Test Cassette.
Service work after replacing the S-VHS Board, Family Board or the Head Amplifier: Adjustment no. 5, 9
Adjustment
Preparation
Adjustment Procedure
1. EE-Level / Sync-
Level Control
R3852 (EE)
2. CVS-Level
R3992 (CVS)
3. White / Dark
Clipper
3.1 White Clipper
R3772 (WC)
3.2 Dark Clipper
R3762 (DC)
4.1 Frequency Devia-
tion Sync Value
VHS
R3752 (SV)
S-VHS
R3795 (SV-S-VHS)
4.2 White Value
VHS
R3802 (WV-VHS)
S-VHS
R3790 (WV-S-VHS)
4. Video Record
Voltage
R3684 (YWV)
5. Playback Amplitu-
de
VHS
R3710 (PBA-VHS)
S-VHS
R3715 (PBA-S-VHS)
7. Dropout level
R3960 (DP)
8. VHS- / S-VHS-
Detection
R3899 (DET)
Set amplitude with R3852 (EE) to 0.4V
PP
.
Set amplitude with R3992 (CVS) to 1V
PP
.
100% CVS signal
A
B
5
µ
s/cm
Set overshoot A with R3772 (WC) to 110% of the CVS
signal.
Set overshoot B with R3762 (DC) to 80% of the CVS
signal.
Set frequency counter with R3752 (SV) to 3.8MHz.
Solder in C2901.
Set frequency counter with R3795 (SV-S-VHS) to 5.4MHz.
Solder in C2871.
Set frequency counter with R3802 (WV-VHS) to 4.62MHz.
Set frequency counter with R3790 (WV-S-VHS) to
6.67MHz.
Set FM signal with R3684 (YWV) – Family Board (IN/OUT
circuit stage) – to 0.28V
PP
.
Set amplitude with R3710 (PBA-VHS) to 0.4V
PP
.
Set amplitude with R3715 (PBA-S-VHS) to 0.4V
PP
.
With R3960 (DP) set the signal as shown in the oscillo–
grams below.
Incorrect
Correct
10ms/cm
With R3899 (DET) set the direct voltage to 2.25V.
Feed in a white test pattern (100% white, 1V
PP
, 0.3V sync
component, 0.7V CVS component).
Oscilloscope: ...................................................... MP
31
AV recording.
Feed in a white test pattern (100% white).
Oscilloscope: ...................................................... MP
36
AV recording "S-VHS"
Feed in a white test pattern (100% white).
Oscilloscope: ...................................................... MP
39
AV recording "S-VHS, Normal Play (NP)"
Frequency counter: ............................................. MP
35
AV recording.
Unsolder C2901.
Unsolder C2871.
Frequency counter: ............................................. MP
35
AV recording (100% white test pattern)
Oscilloscope: ............................. Head Amplifier, MP
1
AV recording.
Oscilloscope: ...................................................... MP
31
Play back a white test pattern (self-made recording).
Oscilloscope: ...................................................... MP
32
Play back a white test pattern (100% white, self-made
S-VHS recording).
Feed in a 50% white or green test pattern without colour carrier
S-VHS recording
Digital Voltmeter: ................................................ MP
34
