Electrical Adjustment Instructions - Durabrand DCD2203 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: Press either "CHANNEL L5 ? ? " or
"CHANNEL K" button on the front panel first, then
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 (FL8A)
Head Switching Position Adjust-
ment
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) VR501
TP302(RF-SW) (Switching Point)
GND (MAIN CBA)
Measurement
Tape
Equipment
FL8A Oscilloscope
Connections of Measurement Equipment
TP751
Main CBA GND
TP302
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(412.7µs) delayed position from the
rising edge of the CH2 head switching pulse wave-
form.
Mode Input
PLAY
-----
(SP)
Spec.
6.5H±1H
(412.7µs±60µs)
Oscilloscope
CH1 CH2
Trig. (+)
1-8-1
Figure 1
EXT. Syncronize Trigger Point
CH1
1.0H
6.5H±1H (412.7µs±60µs)
CH2
Switching Pulse
0.5H
V-Sync
H9400EA