Electrical Adjustment Instructions - FUNAI 23C-250 Service Manual

ELECTRICAL ADJUSTMENT INSTRUCTIONS

General Note: "CBA" is an abbreviation for "Circuit
Board Assembly".
Notes:
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: Press either channel " " or " "
button first, then the " PLAY " button (VCR's Front
Panel only).
Test Equipment Required
1. Oscilloscope: Dual-trace with 10:1 probe, V-Range:
0.001~50V/Div., F-Frange: AC~DC-20MHz
2. Alignment Tape ( FL6A )
1. Head Switching Position
Adjustment
Purpose: To determine the Head Switching point dur-
ing playback.
Symptom of Misadjustment: May cause Head
Switching noise or vertical jitter in the picture.
Test Point
TP751(V-OUT)
TP502(RF-SW) VR501 (SW-P)
GND
Tape
FL6A
Connections of Measurement Equipment
TP751
Main CBA
GND
TP502
EXT. Synchronize Trigger Point
CH1
1.0H
CH2
Switching Pulse
Reference Note:
TP502, TP751, VR501 : Main CBA
• Play back the test tape and adjust VR501 so that the
V-sync front edge of the CH1 video output wave-
form is at the 6.5H(412.7µs) delayed position from
the rising edge of the CH2 head switching pulse
waveform.
1-6-1
Adj. Point Mode
PLAY
(SP)
Measurement
Spec.
Equipment
6.5H±1H
Oscilloscope
(412.7±60µs)
Oscilloscope
CH1
Trig. (+)
Figure 1
V-Sync
0.5H
6.5H
H8740EA
Input
----
CH2