Electrical Adjustment Instructions - Durabrand AD214BD 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 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 "CHANNEL L5 ? ? " or
"CHANNEL K" button on the remote control unit
first, then the "PLAY" button (Front Panel only).
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
J23(V-OUT)
TP502(RF-SW) (Switching Point)
GND
Tape
FL6A
Connections of Measurement Equipment
J23
Main CBA
GND
TP502
EXT. Syncronize Trigger Point
CH1
1.0H
6.5H±1H (416µs±64µs)
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.
1-6-1
Adj.Point Mode
VR501
PLAY
(SP)
(MAIN CBA)
Measurement
Spec.
Equipment
6.5H±1H
Oscilloscope
(416µs±64µs)
Oscilloscope
CH1
Figure 1
0.5H
Switching Pulse
FEGVCREA
Input
-----
CH2
Trig. (+)
V-Sync