Sony TC-KA6ES Service Manual page 12

Bias 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.
2. Adjust T101 (L-CH) and T201 (R-CH) so that the digital
voltmeter reading becomes minimum.
Digital
voltmeter
B+ (+8.5V)
Adjustment Value : 120mV or less
(This Value is measured using CS-413 after bias adjustment.)
Bias and Recording level adjustment
Condition :
REC LEVEL control : Specified recording position (page 10)
Procedure :
1. Mode : simultaneous record and playback
LINE IN
AF OSC 315Hz, 50mV (—23.8dB)
10kHz, 50mV (-23.8dB) oo
"3 10kQ
O| Attenuator
o-oo
11
OOO
_
Crete
Oscilloscope VTVM J
ed) ee
oO
| |
LINE OUT
2. Adjust the following controls so that the minimum output
becomes the specified output level.
(1) RV104 (L-CH) and RV204 (R-CH) ...... Bias adjustment
(2) RV103 (L-CH) and RV203 (R-CH) ...... Recording level
adjustment
Adjustment Value :
(1) Level of 10kHz against 315Hz : 0 + 0.3dB
(2) 315Hz level : 48.3 to 51mV (—24.1 to —23.5dB)
Metal Bias Adjustment
Condition :
REC LEVEL control : Specified recording position (page 10)
Procedure :
1. Mode : simultaneous record and playback
315Hz, 50mV (—23.8dB)
LINE OUT
2. Adjust RV505 so that 10kHz R-CH output is + 0.3dB
relative to the 315Hz output.
Calibration Adjustment
Condition :
CALIBRATION switch : ON
TP801 : The state of short-circuit
Adjustment method (Oscillation input level) :
1. Short-circuit the test point TP801 of system control (A)
board.
2. Adjust RV904 (HIGH), RV905 (MID) and RV906 (LEVEL)
to become the level meter as the following display.
a HIGH
Vv
SRS MID
LEVEL >ma<
3. As for HIGH and MID, the segment with AV mark in the
left side should be lit. (approve of flashing)
And when the left segment is flashing, the right segment is
approved of flashing.
4. As for LEVEL, @ mark should be lit. (Both ends are
approved of flashing.)
5. Release the short-circuit of TP801.