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2-3.
SERVO SYSTEM CHECK
2-3-1.
RF Switching Position Adjustment
(MA-372 Board)
[Adjustment Purpose]
To adjust the link of the A-ch and B-ch of the tape playback outputs.
To make the unit compatible with other tapes and units. If this
specification is not satisfied, the link will appear on the screen and
the screen will be disrupted, etc.
Mode
Playback
Signal
Alignment tape: SP color bar portion
Measurement point
CH1: CN262 pin 1 (PB RF)
CH2: CN262 pin 2 (RF SWP)
Measuring instrument
Oscilloscope
Adjusting element
Remote commander CH+/–
Specified value
A=minimize
[Adjustment Method]
1) Playback the alignment tape.
2) Short CN262 pin 5 to Ground.
3) Check that "A P" is indicated on FL display.
4) Adjust so that part A becomes minimized at CH +/–.
5) Write data in EEPROM by pressing PAUSE button.
6) The display "A P" disappears and then the Adjustment mode
terminates.
A
CH1
PB RF
CH2
RF SWP
Fig. 6-2-3
2-4.
AUDIO SYSTEM ADJUSTMENT
[Connecting Instruments]
CN500
3 A (L) OUT
4 A GND
J481 AUDIO IN
Audio level meter
or distortion meter
Audio oscillator
600 Ω
47 kΩ
Attenuator
VTR
Fig. 6-2-4
2-4-1.
Normal Audio System Adjustment
• Make adjustment in the SP mode unless otherwise specified. Use
a normal VHS cassette for an adjustment tape.
• Set AUDIO MONITOR to normal.
2-4-2.
ACE Head Adjustment
Refer to the VHS mechanical adjustment manual
MECHANISM) (9-921-647-11).
2-4-3.
E-E Output Level Check
[Adjustment purpose]
Confirm that the output level adjust the reference input is within the
specification.
Mode
E-E
Signal
400 Hz, –6.3 dBs
Measurement point
CN500 Pin 3
Measuring instrument
Audio level meter
Specified value
–6.3 ± 2 dBs
[Check Method]
1)
Input signal of 400 Hz and –6.3 dBs to the J480.
2)
Check that the audio output level is –6.3 ± 2 dBs.
2-4-4.
Frequency Response Check
[Adjustment purpose]
Confirm that the frequency characteristic is within the specification.
Mode
REC and PB (SP mode)
Signal
400 Hz, –26.3 dBs
7 kHz, –26.3 dBs
Measurement point
CN500 Pin 3
Measuring instrument
Audio level meter
Specified value
0 ± 3 dB
Note: Tape path adjustment must have been completed.
[Confirmation Method]
1)
Supply a signal of 400 Hz, –26.3 dBs to J481 AUDIO IN.
2)
Connect the audio level meter to CN500 Pin 3.
3)
Adjust the attenuator so that the audio level meter will indicate
–26.3 dBs.
4)
Make recording in the SP mode.
5)
Set an audio line input signal to 7 kHz and make recording.
6)
Playback a recorded portion, and measure output levels at 400
Hz and 7 kHz.
7)
Confirm that the 7 kHz playback output level within a range of
the 400 Hz playback output level 0 dB to ± 3 dB.
6-3
2-5.
ADJUSTING PARTS LOCATION DIAGRAM
MA-372 BOARD
(CONDUCTOR SIDE)
LINE-1(TV)
(S
CN500
E
Q601
B
B
Q600
E
B
E
Q602
JK-179 BOARD
(CONDUCTOR SIDE)
J481
LINE-2 IN
CN262
1
5
6-4
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