Mhz Deviation Adjustment (Vc-197 Board) - Sony GV-A500 Service Manual

1. 1.5 MHz Deviation Adjustment (VC-197 board)

Sets the spectrum of the L-ch (L+R/2 signal) level modulated during
recording. If deviated, the crosstalk of the audio signal will occur
and the audio level will drop during both playback and recording.
Mode VTR recording
Signal Input the AFM DEV jig output signal
to the right and left audio input
terminals (Note 1)
Measuring point CH1: AFM DEV jig TP31
CH2: AFM DEV jig TP3
Measuring device Oscilloscope
Adjustment page F
Adjustment address 52
Specified value The difference between CH1 signal
and CH2 signal should be minimum.
Connection:
1) Connect CN2 of the AFM DEV jig to CN207 of the VC-197
board.
2) Connect the audio output terminal (J1 and J2) of the AFM DEV
jig to AUDIO terminal of the unit.
3) Connect TP28 (DC), TP27 (GND) of the AFM DEV jig to the
DC power supply (+7 Vdc to +9 Vdc).
4) Set the AFM DEV jig switches to the following positions.
S1 ············· BIL position
S2 ············· NT position (NTSC)
PAL position (PAL)
S3 ············· SIN position
Note : NTSC model : GV-A500
PAL model : GV-A500E
Adjustment method:
1) Match the vertical ranges of CH1 and CH2 of the oscilloscope
to each other.
2) Set the oscilloscope to the ADD mode and CH2 to the INV
(inverse) mode.
3) Set page: 0, address: 01, data: 01.
4) Change the data of page: F, address: 52 and minimize the audio
signal level difference (A).
5) Press the PAUSE button of the adjusting remote commander.
6) Set page: 0, address: 01, data: 00.
Approx. 2msec
Fig. 5-3-25.
ADD mode
CH2 INV mode
A
2. 1.7 MHz Deviation Adjustment (VC-197 board)
Sets the spectrum of the R-ch (L–R/2 signal) level modulated during
recording. If deviated, the crosstalk of the audio signal will occur
and the audio level will drop during both playback and recording.
Mode
Signal
Measuring point
Measuring device
Adjustment page
Adjustment address
Specified value
Connection:
1) Connect CN2 of the AFM DEV jig to CN207 of the VC-197
board.
2) Connect the audio output terminal (J1 and J2) of the AFM DEV
jig to AUDIO terminal of the unit.
3) Connect TP28 (DC), TP27 (GND) of the AFM DEV jig to the
DC power supply (+7 to +9 Vdc).
4) Set the AFM DEV jig switches to the following positions.
S1 ············· BIL position
S2 ············· NT position (NTSC)
PAL position (PAL)
S3 ············· SIN position
Note : NTSC model : GV-A500
PAL model : GV-A500E
Adjustment method:
1) Match the vertical ranges of CH1 and CH2 of the oscilloscope
to each other.
2) Set the oscilloscope to the ADD mode and CH2 to the INV
(inverse) mode.
3) Set page: 0, address: 01, data: 01.
4) Change the data of page: F, address: 53 and minimize the audio
signal level difference (A).
5) Press the PAUSE button of the adjusting remote commander.
6) Set page: 0, address: 01, data: 00.
Approx. 2msec
5-37
VTR recording
Input the AFM DEV jig output signal
to the right and left audio input
terminals
CH1: AFM DEV jig TP32
CH2: AFM DEV jig TP2
Oscilloscope
ADD mode
CH2 INV mode
F
53
The difference between CH1 signal
and CH2 signal should be minimum.
A
Fig. 5-3-26.