Panasonic Omnivision VHS PV-V402, Руководство по обслуживанию

Страница: 40 / 105

Dual Trace Oscilloscope
VHS Alignment Tape (VFMS0003H6)
Post Adjustment Driver (VFK0329)
H-Position Adjustment Driver (VFK0330)
6.2.2.2.1. ENVELOPE OUTPUT ADJUSTMENT
The height of the P2 and P3 Posts replacement part is preadjust at the factory.
Purpose:
To achieve a satisfactory picture and secure precise tracking.
Symptom of Misadjustment:
If the envelope is output poorly, much noise will appear in the picture.
Then the tracking will lose precision and the playback picture will be
distorted by any slight variation of the tracking control circuit.
Equipment Required:
Post Adjustment Driver (VFK0329)
1. Insert the alignment tape.
2. Press and hold FF button and CH DOWN buttons on VCR together
over 5 seconds in power off condition.
The power comes on and the unit goes into service mode.
3. Play back the alignment tape.
4. To enter Tracking center mode, press PLAY button in Play back mode.
"TRACKING CENTER" will be displayed on the TV monitor.
5. Connect the oscilloscope to TP3002 on the Video Signal Process
Section of the Main C.B.A. Use TP6205 as a trigger.
6. Confirm that the RF envelope is flat enough (V1/V-max. is 0.7 or more).
If not, with Post Adjustment Driver, adjust P2 and P3 post height so
that the envelope waveform becomes as flat (V1/V-max. is 0.7 or more)
as possible (No envelope drop). If the envelope drop appears on the
left-half of the waveform, adjust P2 post height. If the envelope drop
appears on the right-half of the waveform, adjust P3 post height.
CAUTION:
Overtightening P2 and P3 posts may cause the threads to strip.
Note:
It will be possible to confirm Step 6 according to following steps.
1. Release the Tracking center mode.
2. Press the Tracking Control Up or Down button on remote control.
Make sure that the envelope waveform remains flat. If not, readjust P2
40
MC-Service