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8-3.
AUDIO CIRCUIT ADJUSTMENTS
BIAS LEVEL Adjustment _
Measurement point
TP201 (HOT)
MU 170 (00) 0 D))
Measurement equipment]
AC voltmeter
.
:
Frequency counter
Specified value
22mV
:
71 + SkHz
Adjustment Method
1) Load a cassette tape, and set the voltage between
TP202(COLD)and TP201(HOT) to 22mV(220 uw A).
2) Make sure that the oscillation frequency is 71kHz +
SkHz.
a
NORMAL PB LEVEL Adjustment
Adjustment Method
1) Play back the Alignment tape (MH-1), and adjust so
the output voltage to — 7 + 1dBm.
ALC OUTPUT Checking
Adjustment Method
1) Make standard input into audio input jack and, in the
E-E mode, wait until the output voltage of the audio
output jack stabilizes.
2) Set the input level to — 20dB and to +20dB and
confirm that the fllowing standards are fulfilled.
Input Level
Output Level
+ 20dB
—6 + 2dBs
0dB
—7 + 3dBs
— 20dB
—28 + 4dBs
RECORD CURRENT Checking
a
0
TP202 (COLD)
Adjustment Method
1) Input the reference input to be in record state.
2) Short-circuit between Q2001 base and emitter to stop
the bias oscillation.
(Or, pass the output signal
between TP202 (COLD) and TP201(HOT) through
1kHz B. P. F. to remove the bias.)
3) Make sure that the record current is 2.7 + 0.5mV.
FREQUENCY CHARACTERISTIC Check and Adjustment
a
ee
AC voltmeter
:
Adjustment Method
1) In 2H mode, play 1kHz and 10kHz signals. Confirm
that the 10kHz play level is in — 1dB to +2dB range
in relation to 1kHz play level.
.
Recording and Playback Output Check and Distortion
Factor Check
[ise [Rennes Pane
Specified value
Playback level
: — 7+ 3dBm
Distortion factor : 3% or less
Adjustment Method
1) Make standard input (1kHz) into audio input jack
and, in the E-E mode, wait until the output of the
audio output jack stabilizes.
2) Play recording in the 2H mode. Confirm that play
output is
—
7 + 3dBs. Also, confirm that the
distortion rate is 3% or less
— 150 —
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