Sony TC-K808ES Service Manual page 11

Blas Consumption Current Adjustment
Note: The bias consumption current must be adjusted before adjusting
the record bias. Retry record bias adjustment after the bias
consumption current is adjusted.
Procedure:
1,
Set semi-fixed resistors RV104 (L-CH), RV204 (R-CH) and RV505
for record bias adjustment to mechanical center, and select the
recording mode without applying a signal.
Adjust T101 (L-CH) and T201 (R-CH) so that the digital voltmeter
reading becomes minimum.
Digital
voltmeter
B+ (+8.5V)
Specification: 120mV or less
(This value is measured using CS-413 after bias adjustment.)
Blas and Recording level adjustment
Condition:
REC LEVEL control: Specified recording position (Page 9)
Procedure:
1.
2.
Mode: simultaneous record and playback
LINE IN
315Hz, 25mV (—30dB)
AF 7
10kHz, 25mV (—30dB) Blank tape
10kQ CS-222
Ay Bass Le
Oscilloscope VTVM J
LINE OUT
Adjust the following controls so that the minimum output becomes
the specified output level.
(1) RV104 (L-CH) and RV204 (R-CH) srrrrsreres Bias adjustment
(2) RV103 (L-CH) and RV203 (R-CH) serrrtssees Recording level
adjustment
Adjustment Value:
(1) Level of 10kHz against 315Hz: 0+0.3dB
(2) 315Hz level: 30.9 — 33.1mV (—28.0 — —27.4dB)
Metal Bias Adjustnemnt
Condition:
REC LEVEL control: Specified recording position (page 9)
Procedure:
1, Mode: simultaneous record and playback
315Hz, 25mV (—30dB)
LINE OUT
2. Adjust RVSO5 so that 10kHz R-CH output is 0+0.3dB relative to
the 315Hz output.
Calibration Adjustment and Level Meter Adjustment
Condition:
CALIBRATION switch: ON
Procedure (oscillation output level adjustment):
1, Mode: record (No signal to LINE IN)
VIM Blank tape
[A TP501 CS-222
2, Adjust RV508 so that the 400Hz check point level is 2.32 —2.59V
(9.5dB—10.5dB).
3. Adjust RV507 so that the 8kHz check point level is 2.32 — 2.59V
(9.5dB—10.5dB).
Procedure (level meter adjustment):
1. Record mode (No signal to LINE IN)
2. Adjust RV102 to higher side, then lower it gradually.
Adjsut so that the level "'a" higher by one point than 0dB of LOW
FREQ segment (lower) of CAL level meter turns off.
3. Adjust RV202 so that HIGH FREQ segment (upper) up to 0dB
position of CAL level meter turns on.
HIGH: Blinking of level "a" higher by 1 point is acceptable.
HIGH
REC CAL FREQ L oem mem wae ee ee
LOW Bo ew ee eee oe ee oe
FREQ '
REC EO CAL NOP
"gy!
LOW: Blinking of level "a" higher by 1 point is not acceptable.