Electrical Adjustment Instructions - Durabrand ADB2737BD Service Manual

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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 com-
pleted. 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 [PROG. L5 ? ? ] or
[PROG. K] button on the front panel first, then the
[VCR 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 position during
playback.
Symptom of Misadjustment:
May cause Head Switching noise or vertical jitter
in the picture.
Test point
J236(JK1-V-OUT)
TP504(RF-SW) (Switching Point)
GND
Tape
FL6A
Connections of Measurement Equipment
J236
GND
Main CBA
TP504
Adj.Point Mode
VR501
PLAY
(SP)
(MAIN CBA)
Measurement
Spec.
Equipment
6.5H±1H
Oscilloscope
(416µs±64µs)
Oscilloscope
CH1
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 (416µs±64µs) delayed position
from the rising edge of the CH2 head switching pulse
waveform.
Input
-----
CH2
Trig. (+)
1-7-1
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Figure 1
1.0H 0.5H
6.5H±1H (416µs±64µs)
Switching Pulse
18/6/2013
V-Sync
H9710EA