Panasonic PV-M2738 Operating, Service Manual, Page: 47 / 151

2-26
Eq Pulse
T
1V 5V
One Horizontal Line
Start of V Sync
CH1 : TP3001
CH2 : TP6205
2ms 2 0.1ms
CH1: TP2005
CH2: TP2006
5V 5ms 1 5V
1
2
3 4 5
6
1. Connecting Point
3. Volts/DIV
5. Time/DIV
2. Volts/DIV
4. Connecting Point
6. Trigger Channel of
the Scope
1 : CH1
2 : CH2
CH1
CH2
ELECTRICAL ADJUSTMENT
Note:
Picture Tube Ass'y is preadjusted at factory and should
not be disturbed unless absolutely necessary.
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. MTS/SAP Signal Generator
(TV Multi-Channel Sound Modulator (U.S.A.))
4. Frequency Counter
Frequency Range : 0 to 150MHz
5. Plastic Tip Driver and Non-Metal Driver
6. Isolation Transformer (Variable)
7. VHS Alignment Tape (VFMS0003H6)
8. White Pattern Generator
HOW TO READ THE ADJUSTMENT
PROCEDURES
Fig. E1
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 adjust the R6201
(PG SHIFTER) so that the leading edge of the head
switching pulse is placed 6H +/- 1H (0.38 +/- 0.06msec.)
before the start of the vertical sync pulse.
Fig. E2