Hitachi DV-RV8500E, Service Manual

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5 - 2
Adjustment / Maintenance > VCR Electrical Adjustment
5-2 VCR Electrical Adjustment
5-2-1 Head switching adjustment
(1) Supplement
If the SYSTEM microprocessor (IC501) or EEPROM (IC503) on VCR P.C.B is replaced, be sure to
perform the head switching adjustment.
If the drum assembly is replaced, be sure to perform the X-value adjustment and head switching
adjustment.
Fig. 5-2-1 Connection Diagram
(2) Adjustment method
1) Connect oscilloscope CH-1 to the H/SW terminal on VCR P.C.B, and CH-2 to the VCR VIDEO
terminal on VDR P.C.B.
2) Use CH-1 (H/SW) to trigger the oscilloscope.
3) Play back the alignment tape.
4) Play back the tape for approx. 3 seconds, while simultaneously holding down the REC and
PLAY buttons on recorder for several seconds (FL display: _ _).
5) Simultaneously hold down the REC and PLAY buttons on recorder for several seconds again:
The adjustment will automatically start.
When the adjustment is complete, “PG” will appear in the FL display.
6) Observe the waveforms on oscilloscope, and make sure that the phase from the vertical sync
signal to the leading edge (trigger position) of H/SW pulse is 6.5H ± 0.5H.
Fig. 5-2-2 Waveform Diagram
H/SW
(TP)
TP
[VCR
VIDEO]
(CH2)
(CH1)
Oscilloscope
CH1 CH2
H/SW
(VCR P.C.B)
VCR P.C.B
VDR P.C.B
"VCR VIDEO"
(VDR P.C.B)
H/SW
(50µs/div.)
V-Sync
6.5H±0.5H
Trigger Point
VCR VIDEO
(500mV/div.)
1H 1H
(5V/div.)