Sony RMT-V259, Service Manual

Page: 71 / 93

7-3
2-4. AUDIO SYSTEM ADJUSTMENTS
• Adjust both Lch and Rch.
[Connection]
Fig. 7-2-4.
2-4-1. Hi-Fi Audio System Adjustment
(EXCEPT SLV-SE350/SE500)
• Set switches and knobs to the following positions to make ad-
justment unless otherwise specified.
INPUT SELECT switch ................... LINE
AUDIO MONITOR .......................... STEREO
[Adjustment Sequence]
1. AF Switching Position Adjustment
2. Frequency Response Check
3. Overall Level Characteristic and Distortion Factor
Check
4. Overall S/N Check
1. AF Switching Position Adjustment
(MA-373 BOARD)
Purpose:
Adjust the interval between A CH and B CH of tape playback
output. Improve the interchangeability with other tapes and sets.
When it is out of order, noisy sound is increased and big noise is
heard.
Mode PB
Signal Alignment tape SP mode
color bar
Measurement point CH1: Pin
2
of CN262
CH2: Pin
1
of CN263
Measuring Instrument Oscilloscope
Specified Value Fig. 7-2-5
Adjusting Method:
1) During playback, connect MA-373 board CN262 pin
3
and
the pin
5
for about 1 second to activate the RF switching
position adjustment mode.
2) Press the record button to activate the AF switching position
adjustment mode.
3) Check appear “A H” on FL display.
4) Using the ch and – buttons, minimize a chipped por-
tion. At this time, confirm that a noisy sound is not heard.
5) Press the pause button.
Fig. 7-2-5.
2. Frequency Response Check
Purpose:
Confirm that the frequency characteristic is within the specifica-
tion.
Mode REC and PB (SP, LP mode)
Signal 400 Hz, –26.3 dBs
30 Hz, –26.3 dBs
20 kHz, –26.3 dBs
Measurement point Audio output terminal
Measurement equipment 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 both L and R chan-
nels of Audio Line Input.
2) Connect the audio level meter to the Audio Line Output.
3) Adjust the attenuator so that the audio level meter will indi-
cate –26.3 dBs.
4) Make recording.
5) Set an audio line input signal to 30 Hz and make recording.
6) Set an audio line input signal to 20 kHz and make recording.
7) Playback a recorded portion, and measure output levels at 400
Hz and 30 Hz and 20 kHz.
8) Confirm that the 30 Hz and 20 kHz playback output level within
a range of the 400 Hz playback output level 0 ± 3 dB.
CH2
CH1
RF SWP
OK
NG
Audio
generator
Attenuator
600
Ω
47 k
Ω
VCR
Audio level meter or
distortion meter
AUDIO LINE OUT
AUDIO LINE IN
Feed signal both
channelssimultaneously.