Sony TC-KB920S Service Manual page 11

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Tape Speed Adjustment
Procedure:
Mode: playback
test tape
WS-48B
(3 kHz, 0 dB)
set
1. Set to FWD playback mode.
2. Adjust RV71 so that the frequency counter reading becomes
3,000±90 Hz.
3. Frequency difference between the beginning and the end of
the tape should be within 3%.
Adjustment Location: AUDIO board (See page 12.)
Sample value of Wow and Flutter: 0.3% or less W.RMS (JIS)
Playback Level Adjustment
Procedure:
Mode: playback
test tape
P-4-L300
(315 Hz, 0 dB)
TE
L 13942296513
Adjust RV121 (L-CH) and RV221 (R-CH) so that the reading on
level meter meets the adjustment limits below.
Adjustment Limits:
LINE OUT level: –7.7±0.5 dB (0.301 to 0.338 V)
Level difference between channels: within 0.5 dB
Check that the LINE OUT level does not change even if Playback
and Stop operation is repeated several times.
Adjustment Location: MAIN board (See page 12.)
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frequency counter
47 k Ω
+
–
LINE OUT
(WS-48B)
level meter
47 k Ω
+
set
–
LINE OUT
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8
Bias Consumption Current Adjustment
Procedure:
LINE IN
(no signal)
set
1. Set RV103 (L-CH) and RV203 (R-CH) to mechanical center
and turn the set recording mode.
2. Connect digital voltmeter as shown by the following table.
3. Adjust the following transformers for the minimum readings
on the digital voltmeter.
Measurement Point
2 and 3, TP321
L-CH
1 and 2, TP321
R-CH
Adjustment Location: MAIN board (See page 12.)
Record Bias Adjustment
Setting:
REC LEVEL control: Standard Record (See page 10.)
Procedure:
Q Q
1. Mode: record and playback
3 6 7 1 3 1 5
AF OSC
Attenuator
level meter
2. Adjust RV103 (L-CH) and RV203 (R-CH) so that 10 kHz play-
back output is 0±0.3 dB relative to the 315 Hz output.
Adjustment Location: MAIN board (See page 12.)
co
.
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9 4 2 8
CS-413 blank tape
47 k Ω
TP321
3 2 1
B+ (+7.5 V)
Adjustment Part
T101
T201
0 5 8 2 9 9 4 2 8
LINE IN
315 Hz
50 mV (–23.8 dB)
10 kHz
10 k Ω
600 Ω
set
47 k Ω
+
–
LINE OUT
m
9 9
digital voltmeter
–
+
Value
minimum
9 9
CS-123
blank tape