Panasonic Omnivision PV-9661, Service Manual

Page: 290 / 407

6.3. ELECTRICAL ADJUSTMENT
6.3.1. TEST EQUIPMENT
To do all of these electrical adjustments, the following
equipment is required.
1. Dual-Trace Oscilloscope
Voltage Range: 0.001 to 50V/Div.
Frequency Range: DC to 50MHz
Probes: 10:1, 1:1
2. NTSC Video Pattern Generator
3. Color TV Receiver or Monitor
4. Plastic Tip Driver and Non-Metal Driver
5. Isolation Transformer (Variable)
6. VHS Alignment Tape (VFMS0003H6)
6.3.2. HOW TO READ THE ADJUSTMENT
PROCEDURES
Fig. E1
6.3.3. PG SHIFTER ADJUSTMENT
Purpose: Determine the Video Head Switching
Point during Playback.
Symptom of
Misadjustment: May cause Head Switching Noise and/or
Vertical Jitter.
Test Point: TP3001 (Main C.B.A.)
TP6205 (Main C.B.A.)
Adjustment: R6201 (Main C.B.A.)
Specification: T = 6 +/- 1H (0.38 +/- 0.06msec.)
Mode: SP Playback
Equipment: Oscilloscope,
VHS Alignment Tape (VFMS0003H6)
1. Connect the channel-1 scope probe to TP3001 and the
channel-2 scope probe to TP6205. Trigger from channel-2.
2. Playback the VHS alignment tape, and then connect
TP6003 to GND to be in PG Shifter Adjustment mode.
3. Adjust the R6201 (PG SHIFTER) so that the trailing edge of
the head switching pulse is placed 6H +/- 1H (0.38 +/-
0.06msec.) before the start of the vertical sync pulse.
4. Disconnect TP6003 and GND to set the adjustment value of
PG Shifter.
Fig. E2
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PV-9661 / PV-9662