Sony TC-377 Service Manual page 18

14. Dummy Coil Adjustment
Control/Switch Setting:
TAPE SELECT switch:
TPAE SPEED selector:
MONITOR switch:
LINE RECORD
VOLUME control:
NORMAL -
7% ips (19 cm/s)
TAPE
'See page 16
Procedure:
1. Mode: stereo record
' af osc
"s
oO
blank tape
LINE IN a a
20kHz, -30d8 (25mV) cae
LINE OUT (L, R)
Memorize VTVM readings.
Set L-channel (R-channel) only
mode,
in record
Adjust L502.(L501) with non-magnetic screw-
driver, taking care not to break the core, so
that VTVM reading is the same as that obtained
' in step 2.
Adjustment Location:
L502
for L-CH
L501
for R-CH
bias ose circuit board
15. Erase Ratio Measurement
Control/Switch Setting:
TAPE SELECT switch:
TAPE SPEED selector:
MONITOR switch:
.LINE RECORD
VOLUME control:
NORMAL
7% ips (19 cm/s)
TAPE
See page 16
Procedure:
1. Mode: stereo record
af osc
=) attenuator
oo
1000
oO O
LINE IN
400 Hz, OdB (0.78V)
blank tape
2. Rewind half of the recorded part.
3. Mode: stereo record (erase)
rewound portion
no input signal
4. Mode: playback
recorded
portion
400 Hz bandpass
100k. filter
LINE OUT
Specification:
Recorded Signal VTVM Reading
level difference: greater
| erased portion | | erased portion | than 65 dB