41
37VT-26H(GY)
Notes:
»
Before the adjustment:
Electrical adjustments described here are often required after replacement of electronic components and mechanical
parts such as video heads.
Check that the mechanism and all electric components are in good working condition prior to the adjustments,
otherwise adjustments can not be completed.
»
Instruments required:
Dual-trace oscilloscope
Blank video cassette tape
Colour bar generator
Alignment tape (VROCBZF)
»
Adjustment of the VCR should be done in the TV/VCR combinated style. But there is a function that is able
to cut off high voltage of TV. Namely, you can check only VCR part by taking the plug of P2002 off the
socket SC2002 in Main PWB (PWB-A). Therefore you can use this function on the occasion of checking
and adjustment of VCR part.
ADJUSTMENT OF THE VCR ELECTRICAL CIRCUITRY
SERVO CIRCUIT ADJUSTMENT
ADJUSTMENT OF HEAD SWITCH-
ING POINT
Figure 2-1.
Measuring
Dual-trace oscilloscope
instrument
Mode
Playback
Cassette
Alignment tape(VROCBZF)
Test point
TP2201 (Video Out) to CH1
TP3302 (Head Switching Pulse,
Trigger) to CH2
Control
Remote Control
Specification
5.5
±
0.5H (lines)
5.5
±
0.5H(Iines)
V-sync.
CH-2
HEAD
SWITCHING
PULSE
CH-1
VIDEO OUT
CH-1: 1V/div 50
µ
sec/div
CH-2: 2V/div 50
µ
sec/div
1. Play back the alignment tape (VROCBZF)
2. Press the CH
"
(TR
) button and the "0" button of
remote control at the same time to turn the set into
the adjustment mode for the head switching point.
"TEST" is displayed on the TV screen.
3. Connect a dual trace oscilloscope to the test points
TP2201 (Video Out) and TP3302. (Trigger the
oscilloscope with the head switching pulse on
TP3302.)
4. Press the PLAY button of remote control to make the
adjustment of the head switching point. The head
switching point is automatically adjusted so that the
leading edge of head switching pulse is set 5.5H
(lines) ahead of the vertical sync as shown in Figure
2-1, then the adjustment mode is released. "TEST"
disappears on the screen.
5. Press the STOP button to stop the tape.
Notes:
1
The data of this adjustment for the head switching
point is memorized in the EEP-ROM IC.
2
Pressing both the CH
"
(TR
) button and the "0"
button at the same time transmits the test code. When
the unit receives this test code in the playback mode,
the unit is turned into the adjustment mode for the
head switching point and "TEST" is displayed at the
center of the monitor screen. This function is available
to the remote control : RRMCG1521PESA.
