Electrical Adjustment Instructions; Head Switching Position Adjustment - Philips MX5100VR/00 Service Manual

ELECTRICAL ADJUSTMENT INSTRUCTIONS

General Note: "CBA" is an abbreviation for
"Circuit Board Assembly."
NOTE:
1.Electrical adjustments are required after replacing
circuit components and certain mechanical parts. It
is important to do these adjustments only after all
repairs and replacements have been completed.
Also, do not attempt these adjustments unless the
proper equipment is available.
2.To perform these alignment / confirmation proce-
dures, make sure that the tracking control is set in
the center position: First, press the "VCR" button
on the remote control unit to put the System in
VCR mode. Second, press either "LCH? ? " or "KCH"
button on the remote control unit, then press the
"PLAY" button on the front panel.
Test Equipment Required
1.Oscilloscope: Dual-trace with 10:1 probe,
V-Range: 0.001~50V/Div.,
F-Range: DC~AC-20MHz
2.Alignment Tape (FL6A)

Head Switching Position Adjustment

Purpose:
To determine the Head Switching point during
playback.
Symptom of Misadjustment:
May cause Head Switching noise or vertical jitter
in the picture.
Test point Adj.Point
TP751(V-OUT)
TP504(RF-SW) (Switching Point)
GND (MAIN CBA)
Measurement
Tape
Equipment
FL6A Oscilloscope
Connections of Measurement Equipment
TP751
Main CBA GND
TP504
Mode
VR501
PLAY
(SP)
Spec.
6.5H±1H
(416.0µs±60µs)
Oscilloscope
CH1
Trig. (+)
EXT. Syncronize Trigger Point
CH1
CH2
Reference Notes:
Playback the Alignment tape and adjust VR501 so that
the V-sync front edge of the CH1 video output wave-
form is at the 6.5H±1H (416.0µs±60µs) delayed posi-
tion from the rising edge of the CH2 head switching
pulse waveform.
Input
-----
CH2
1-9-1
Figure 1
1.0H
6.5H±1H (416.0µs±60µs)
Switching Pulse
0.5H
V-Sync
E9515EA