GV 67 �, GV 69 �Adjustment Procedures
GBAdjustment Procedures
1.S-VHS-Board � Luminance (SH)
Test equipment / aids:Oscilloscope (>50MHz) and Frequency Counter with 10:1 Test Probe, Digital Voltmeter, Colour Generator.
Service work after changing the �
� S-VHS Board:�
� Family Board, headwheel or IC7600:Adjustment no. 10
AdjustmentPreparationAdjustment Procedure
1.Record Level,Oscilloscope:............................................................. MP 6With R3487 (REC) set the amplitude to 400mV.
PP
R3487 (REC)AV recording (100% white test pattern, 1VPP, S-VHS)
2.EE Level,Oscilloscope:............................................................. MP 2With R3637(EE) set the amplitude to 2VPP.
R3637(EE)AV recording (100% white test pattern, 1VPP, S-VHS)
3.White / Dark ClipperOscilloscope:............................................................. MP 4
AV recording (100% white test pattern, 1V, VHS, Standard
PPA
Play)
100% Luminance Signal
B
5ms/cm
White Clipper,With R3515(WC) set the overshoot A to 195% of the luminance
R3515(WC)signal.
Dark Clipper,With R3521(DC) set the overshoot B to 65% of the luminance
R3521(DC)signal.
4.Sync ValueFrequency Counter:...................................................MP 3
VHS,
R3503(SV-VHS)AV recording without input signal (VHS)With R3503(SV-VHS)set the frequency to 3.8MHz.
S-VHS,
R3509(SV-S-VHS) AV recording without input signal (S-VHS)With R3509(SV-S-VHS)set the frequency to 5.4MHz.
5.White ValueFrequency Counter:...................................................MP 3
VHS,
R3507(WV-VHS)AV recording (100% white test pattern, VHS)With R3507(WV-VHS)set the frequency to 4.62MHz.
S-VHS,
R3513(WV-S-VHS) AV recording (100% white test pattern, S-VHS)With R3513(WV-S-VHS)set the frequency to 6.67MHz.
6.Luminance WritingOscilloscope:............................................................. MP52With R3765(YWV) set the FM signal to 250mVPP.
Current, R3765(YWV) AV recording (S-VHS)
7.Playback AmplitudeOscilloscope:............................................................. MP 6
VHS,
R3543(PBA-VHS)Play back white test pattern (VHS self made recording)With R3543(PBA-VHS) set the amplitude to 400mV.
PP
S-VHS,
R3545(PBA-S-VHS) Play back white test pattern (S-VHS self made recording)With R3545(PBA-S-VHS) set the amplitude to 400mV.
PP
8.Dropout Level,Oscilloscope:............................................................. MP 7With R3723(DP) set the signal as shown in the oscillograms
R3723(DP)Play back 100% white test pattern (S-VHS self made recording)below.
10ms/cm
9.S-VHS-PB DetectionPlay back a100% white test pattern (self made recording, VHS).
Measure the voltage at MP37 with the digital voltmeter and
note it down.
Reference Level
� S-VHSConnect IC7800, Pin 4 with ground (GND) and Pin 5 with +5V.With R3791(REFS) adjust the voltage so that its level is 0.35V
R3791(REFS)Digital Voltmeter:........................................................MP 39higher than that measured at MP37 .
� VHSConnect IC7800, Pin 4 with +5V and Pin 5 with ground (GND).With R3795(REFV) adjust the voltage so that its level is 0.25V
R3795(REFV)Digital Voltmeter:........................................................MP 38higher than that measured at MP37 .
Remove the connections to ground and +5V.
10.FM ReferenceFeed in a red raster test pattern.Press button "CODE ". Enter the figures 5 2 in this order and confirm
Level for "ACC+"Insert a record/play cassette.with "CODE ". The message "ADJUST" appears on the display.
(Automatic ContourCall up the Service Function with the remote control:On successful completion of this adjustment the display shows
Control)� Press button "CODE " repeatedly until "CODE ----" appears on"READY".
the display.Terminate the Service Function by pressing button A or by
� Enter 4 9 3 4 in this order and confirm with button G.disconnecting the VCR from the mains.
GRUNDIG Service7 |
ACEC
