Sharp VC-MH80 Service Manual page 42

VC-MH80
CHECKING OF LINEAR AUDIO PLAYBACK
LEVEL
Measuring
AC milli-voltmeter
instrument
Mode
Playback
Input signal
Alignment tape. (VROCPZJS)
Test point
Specification I -12.0 + 2dBs
1. Connect an AC milli-voltmeter to the AUDIO OUT
jack.
2. Play!the alignment tape (VROCPZJS).
3. Make sure that the audio output level is as
s p e c i f i e d . ' :
If it is out of specified value, verify the bias
current (ADJUSTMENT OF LINEAR AUDIO BIAS
CURRENT).
CHECKING OF Hi-Fi AUDIO PLAYBACK
LEVEL
' Measuring A C milli-voltmeter
instrument
Mode Playback
Alignment tape. (VRQCBFFS)
Test point
Specification
jack.
2. Play the alignment tape (VROCBFFS).
3. Make sure that the audio output level is as
specified.
Note: Check the PLAYBACK level is less than 2.0dB
both Left channel and Right channels.
CHECKING OF Hi-Fi/NORMAL
RECORD/PLAYBACK LEVEL
Measuring
instrument
Mode
Feed the audio signal shown in table to the left
channel of the AUDIO IN jack.
Connect an AC milli-voltmeter to the left channel
of the AUDIO OUT jack and right channel of the
Make sure so that the mill?voltmeter reads
specified value.
Note: Check the PLAYBACK level is less than 2.0dB
both Left channel and Right channels.
CHECKING OF ,ERASE V0LTAG.E AND OS-
CILLATION FREQUENCY
Measuring
instrument
Mode
Test point
Control
Specification
1. Put the unit in record mode.
2. Connect an oscilloscope across the full erase
head.
3. Make sure the erase voltage across the full erase
head is approx. 4OVp-p or more and frequency is
70 !I 5kHz.
42
AC milli-voltmeter
Record/Playback
Oscilloscope
Record
Full erase head
70 + 5kHz, 4OVp-p or greater