Sony TC-RX77 - Bias Current Adjustment

Bias Current Adjustment
Procedure :
LINE IN
(no signal)
CS-413 blank tape
digital voltmeter
47k
L-CH
oO
x
Ana ces |
TP301
B+ (+7.5V)
1. Set RV103 and RV203 to mechanical center and turn the set
recording mode.
2. Connect digital voltmeter as shown by the following table.
38. Adjust the following transformers for the minimum readings
on the digital voltmeter.
Adjustment Part
@ and @, TP301 T101 not more than
.® and ©, TP301 T201 130mV
Adjustment Location: Main board
Record Bias Adjustment
Setting :
REC LEVEL control: Standard Record (See page 7.)
test pin TP801: short
Procedure :
1, Mode: record
sine
CS-123
10k
Q
blank
tape
ae)
attenuator
Of
ny
o—o
I]
ooo
|
|
eee
|
LINE
IN
1)
315Hz
2)
10kHz
24.5mV(—
30dBs(m))
2. Mode: playback
recorded
portion
po
Playback the signal recorded in step 1.
Confirm that the 10kHz playback output is 0+0.5dB relative to
the 315Hz output. If necessary, adjust RV103 (L-ch) and RV203
(R-ch) for repeat the steps given above.
VTVM
LINE OUT
Adjustment Location: Main board
Record Level Adjustment
Setting:
REC LEVEL control: Standard Record (See page 7.)
test pin TP801: short
Procedure :
1, Mode: record
AF OSC
€) attenuator
(oe)
VTVM
LINE OUT
LINE IN
315Hz, 32.2mV(— 27.7dBs(m))
2. Mode: playback
recorded
portion
LINE OUT
3. Playback the signal recorded in stepl.
Confirm that the signal level is within the adjustment limits
below. If necessary, adjust RV102 (L-ch) and RV202 (R-ch)
repeat the stepl-2.
Adjustment Limits: —27.7dBs(m) + 0.5dB(80.4~34.2mV)
Adjustment Location: Main board
Quick Reverse Sensitivity Adjustment
Conditions :
DIRECTION MODE switch : y=
digital voltmeter
Adjustment procedure:
Quick reverse
adjustment tape
(Leader of the ‘ nee
black cassette
tape) TP802
Connect the digital voltmeter to test point TP802.
2. Load quick reverse adjustment tape and play back the leading
portion in FWD mode.
3. Adjust the RV801 for 4.5+0.5V reading on the digital
voltmeter.
Play back quick reverse adjustment tape in FWD mode again.
Confirm that the reading on the digital voltmeter is “L” level
at the magnetic portion of the tape.
6. Confirm that the tape stop around the tape end (boder of
the leading and the magnetic portions).
Adjustment Location: Main board
220i: