Electrical Adjustment Instructions - Toshiba DVR80KF Service Manual

ELECTRICAL ADJUSTMENT INSTRUCTIONS

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
procedures, make sure that the tracking control is
set in the center position: Press either [PROGRAM
5 ? ? ] or [PROGRAM
first, then the [ B ] (VCR) 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)
NOTE: BOARD MEANS PRINTED CIRCUIT BOARD.
] button on the front panel
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
J171(V -OUT )
TP504(RF-SW) (Switching Point)
GND
Tape
FL6A
Connections of Measurement Equipment
J171
BOARD
GND
AV
TP504
EXT. Syncronize Trigger Point
CH1
1.0H
6.5H±1H (416 μs ± 64 μs)
CH2
Switching Pulse
Reference Notes:
Playback the Alignment tape and adjust VR501 so
that the V-sync front edge of the CH1 video output
waveform is at the 6.5H ± 1H (416μs ± 64μs)
delayed position from the rising edge of the CH2
head switching pulse waveform.
1-7-1
Adj.Point Mode
VR501
PLAY
(SP)
(BOARD AV)
Measurement
Spec.
Equipment
6.5H ± 1H
Oscilloscope
(416μs ± 64μs)
Oscilloscope
CH1
Figure 1
0.5H
Input
-----
CH2
Trig. (+)
V-Sync
E9TK0EA