Service manual

6-10
VL-H870U
VL-H875U
VL-H890U
VL-H870U
VL-H875U
VL-H890U
Measuring instrument Oscilloscope
Mode VCR STOP
Input signal Color bar
Measuring point TL7443
Adjustment address 3A
Adjustment level 400 ± 20 mVp-p
16. Adjustment of REC-Y equalizer (Normal-8 MP)
(1) Input the color bar signal into the video input/output terminal in the VCR STOP mode.
(2) Enter the VCR adjustment mode with an adjustment remote control, and select the address 3A.
Select the address, using the FF or REW key, and fix it with the PB key.
(3) Make an adjustment so taht the SYNC TIP portion gets 400 mVp-p on TL7443.
Select the data, using the FF or REW key, and fix it with the PB key.
After the adjustment, press the STOP key, and exit from the adjustment address 3A.
17. Adjustment of REC-C equalizer
Measuring instrument Oscilloscope
Mode VCR STOP
Input signal Color bar
Measuring point TL7441
Adjustment address 59
Adjustment level 114 ± 10 mVp-p
(1) Input the color bar signal into the video input/output terminal in the VCR STOP mode.
(2) Enter the VCR adjustment mode with an adjustment remote control, and select the address 59.
Select the address, using the FF or REW key, and fix it with the PB key.
(3) Make an adjustment so taht the SYNC TIP portion gets 114 mVp-p on TL7441.
Select the data, using the FF or REW key, and fix it with the PB key.
After the adjustment, press the STOP key, and exit from the adjustment address 59.
18. Adjustment of Y recording current
Measuring instrument Oscilloscope
Mode EE (VCR STOP)
Input signal (Tape) Color bar
Test point CH1; TL7410/TL7401 (GND)
CH2; TL7409/TL7401 (GND)
Adjustment address 105
Adjustment level 144 ± 10 mVp-p
(1) Connect TL7455 and TL 7453 with a proper short-jumper.
(2) Select the address105.
(3) Set the oscilloscope.
1 Connect the SIG side of oscilloscope CH1 probe to the TL7410, the GND side to the TL7401.
2 Connect the SIG side of oscilloscope CH2 probe to the TL7409, the GND side to the TL7401.
3 Using the oscilloscope, invert either CH1 or CH2 signal, and add two signals.
4 At this time match the CH1 and CH2 volts levels.
(4) Change the data value, and make an adjustment to get the specified value at SYNC position.
Measuring instrument Oscilloscope
Mode EE (VCR STOP)
Input signal (Tape) Color bar
Test point CH1; TL7410/TL7401 (GND)
CH2; TL7409/TL7401 (GND)
Adjustment address 104
Adjustment level 34 ± 2 mVp-p
19. Adjustment of C recording current
(1) Connect TL7454 and TL 7453 with a proper short-jumper.
(2) Select the address104.
(3) Set the oscilloscope.
1 Connect the SIG side of oscilloscope CH1 probe to the TL7410, the GND side to the TL7401.
2 Connect the SIG side of oscilloscope CH2 probe to the TL7409, the GND side to the TL7401.
3 Using the oscilloscope, invert either CH1 or CH2 signal, and add two signals.
4 At this time match the CH1 and CH2 volts levels.
(4) Change the data value, and make an adjustment to get the specified value at Red position.
114 mVp-p
Red part
34 mVp-p
Red part
400 mVp-p
SYNC
(TL3402)
144 mVp-p
SYNC
(TL3402)