Sharp VC-H92HM Serviceanleitung Seite 45

CHECKING OF LINEAR AUDIO PLAYBACK
LEVEL
AC milli-voltmeter or
Oscilloscope
Playback
Alignment tape. (VROCBFFS)
(1kHz level conrtol signal)
AUDIO OUT jack
-9dBs*75. (at RCA jack)
+2dB
1. Connect an AC milli-voltmeter or oscilloscope to
the AUDIO OUT jack.
2. Play the alignment tape (VROCBFFS).
3. Make sure that the audio output level is as
specified.
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 AC milli-voltmeter or
instrument Oscilloscope
Input signal Alignment tape. (VROCBFFS)
(1kHz level conrtol signal)
Specification — 5.0dBs + 2dB (at RCA jack) or
— 3.8dBs + 2dB (at 21PIN jack)
1. Connect an AC milli-voltmeter or oscilloscope to
the AUDIO OUT 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.
AC milli-voltmeter or
Oscilloscope
Record/Playback
1kHz, — 3.8dBs (at 21PIN jack)
AUDIO OUT jack
— 5.0dBs + 3dB (at RCA jack) or
— 3.8dBs + 3dB (at 21PIN jack)
1. Feed the audio signal shown in table to the left
channel of the AUDIO IN jack.
2. Connect an AC milli-voltmeter or oscilloscope to
the left channel of the AUDIO OUT jack and right
channel of the AUDIO OUT jack.
3. Make sure so that the milli-voltmeter or
oscilloscope reads specified value.
Note: Check the PLAYBACK level is less than 2.0dB
both Left channel and Right channels.
CHECKING OF ERASE VOLTAGE AND OS-
CILLATION FREQUENCY
Oscilloscope
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 ease
head is approx. 40Vp-p or more and frequency is
70 + 5kHz.
Measuring
instrument
Input signal
Test point
Specification
Measuring
instrument
Test point
Control
Specification