Sanyo VHR-310 Service Manual page 13

AI-14285(N) 2/2
NOTE:
Self-recording means 'Record the audio signal and play
~.-
back the just-recorded portion".
2-3-3.
BIAS LEVEL ADJ.
[Al
Measuring point ] Measuring Equipment IADJ. Condition I
TP201 (HOT)
Oscilloscope REC mode
TP202 (GND)
AC voltmeter
Blank tape
I
AIM. Location
I
ADJ. Value
I
VR201 (BIAS)
] 24 mVrms I
1. Load the VCR with a blank tape and select the record
mode without all incoming signal.
2. After confirming on the oscilloscope that a 70 kHz sine
wave is being output, adjust VR201 (BIAS) so that the AC
L
voltmeter's reading is 24 mVrms.
[B]
PleasuringPoint Measuring Equipment
AW.
Condition
AUDIO OUTPUT Oscilloscope Self-recording
terminal
AC voltmeter Blank tape
Standard audio signal
generator (SG: signal
-33.8 dBs, 400
tiz
-33.8 dBs, 10 kHz)
ADJ. Location ADJ. Value
VR201(BIAS)
-4 dB . +4 dB
between 400 Hz and 10 kHz
1.
2.
3.
4.
5.
6.
7.
Connectthestandard audio signal generatortotheAUDIO
INPUT terminal.
Set the standard audio signal generator's output level to
-33.8 dBs.
Set the standard audio signal generator's frequency to
400 Hz and then 10 kHz. Record each of these frequency
signals.
Play back each of the just-recorded portion.
Confirm that the 10 kHz level on AC voltmeter's reading is
from -4 dB to +4 dB, compared with 400 Hz level.
if the 10 kHz level is less than -4 dB below 400 Hz level or
more than +4dB above 400Hz level, Rotate VR201 (BIAS)
slightly to adjust it.
Repeat steps 3 through 6 if necessary.
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