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[ D-VHS signal circuit]
2. D-VHS switching point
Measuring instrument and condition
Oscilloscope
Test point
TPHSL,TPHSR
EXT trigger
TP2H,TP3Y
Measurement
DIV
10 mV
range
TIM
50 µs
PCB-MAIN (Component side)
TP2H
TP5A
TP5B
TP3Y
PCB-HEAD AMP (Component side)
TPHSR
TPHSL
Adjustment purpose
To adjust the timing for switching the video head during playback.
Symptom when
Images may not be displayed or block noise may appear.
incorrectly adjusted
VCR set up condition
Input signal
– – –
Alignment Tape
Using tape
VCR
Playback
condition
Using Jig
– – –
CH1
CH2
1. Playback an alignment tape (D-VHS [HS/STD] :
STD part).
2. Connect TP5A and TP5B for short circuit.
3. Press the SP/EP button.
4. Connect the CH1 of the oscilloscope with TPHSL,
and connect the CH2 with TP2H.
5. Trigger at the rising edge of the waveform of TP2H.
Set the period from the trigger point of TPHSL to
the specified value as shown in the figure below by
pressing the JOG +/- button or the CH UP/DOWN
button on the remote hand unit.
6. Disconnect TP5A and TP5B.
7. Playback an alignment tape (D-VHS [HS/STD] : HS
part).
8. Carry out step 2 and 3.
9. Press the PLAY button to switch to display "AM" on
the fluorescent display.
10. Carry out step 4 and 5.
11. Press the PLAY button to switch to display "PM" on
the fluorescent display.
12. Connect the CH1 of the oscilloscope with TPHSR,
and connect the CH2 with TP3Y.
13. Trigger at the rising edge of the waveform of TP3Y.
Set the period from the trigger point of TPHSR to
the specified value as shown in the figure below by
pressing the JOG +/- button or the CH UP/DOWN
button on the remote hand unit.
14. Disconnect TP5A and TP5B.
234 ± 15µs
421 ± 15µs
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