Hi-Fi Switching Position Adjustment; (Ma-342 Board); Normal Audio System Adjustment; Ace Head Adjustment - Sony SLV-789HF Service Manual

2-4-2.

Hi-Fi Switching Position Adjustment

(MA-342 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
CH1: CN270 Pin 1 (HF ADJ)
Measurement point
CH2: CN270 Pin 3 (RF SWP)
Measuring instrument Oscilloscope
Adjusting element Remote Commander CH +/–
Specified value B=minimize
[Adjustment Method]
1) Check that "A H" is indicated on FL display.
2) Adjust so that part B becomes minimized at CH +/–.
3) Write data EEPROM by pressing PAUSE button.
4) Check that "A H" indicator turns off.
5) If "A H" indicator is still on, restart RF switching position
Adjustment from the beginning.
CH1
HFADJ
CH2
RF SWP
Fig. 6-2-5
B
2-4-3.

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.
2-4-4.

ACE Head Adjustment

Refer to the VHS mechanical adjustment manual
MECHANISM) (9-921-647-11).
2-4-5.

E-E Output Level Check

[Adjustment purpose]
Confirm that the output level adjust the reference input is within the
specification.
Mode
Signal
Measurement point
Measuring instrument
Specified value
[Check Method]
1) Input signal of 400 Hz and –7.5 dBs to the CJ561 L/R.
2) Check that the audio output level is –7.5 ± 2 dBs.
2-4-6.

Frequency Response Check

[Adjustment purpose]
Confirm that the frequency characteristic is within the specification.
Mode
Signal
Measurement point
Measuring instrument
Specified value
Note: Tape path adjustment must have been completed.
[Confirmation Method]
1) Supply a signal of 400 Hz, –27.5 dBs to CJ561 L/R.
2) Connect the audio level meter to CJ561 L/R.
3) Adjust the attenuator so that the audio level meter will indicate
–27.5 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 ± 3 dB.
6-4
E-E
400 Hz, –7.5 dBs
CJ561 L/R
Audio level meter
–7.5 ± 2 dBs
REC and PB (SP mode)
400 Hz, –27.5 dBs
7 kHz, –27.5 dBs
CJ561 L/R
Audio level meter
0 ± 3 dB
(S