VC-MH705 (serv.man9). Electrical adjustment - Sharp VCR Service Manual (repair manual). Page 3

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30
VC-MH705HM/LM
VC-MH815HM/LM,MH85HM
VC-MH715HM,MH835HM
1. Be sure that E-E level has been correctly specificed.
2. Connect a 75 ohm terminating resistor to the VIDEO
OUT jack and connect an oscilloscope across this
terminating resistor.(See Note below  1)
3. Play a self-recorded tape.
4. Make sure that the output signal amplitude is 1.0Vp-p
as shown in Figure 5-4.
Note:
1
If the 75 ohm terminating resistor is missing, the signal
amplitude will be doubled.
2
Self-recorded tape is a tape which program was re-
corded by the unit being adjusted.
1.0 Vp-p
Figure 5-4.
CHECKING OF PLAYBACK LEVEL
Measuring
Oscilloscope
instrument
Mode
Record/Playback
Cassette
Self-recorded tape
(See Note below 2)
Specification
1.0
±
0.2Vp-p
1. Connect an AC milli-voltmeter to the AUDIO OUT jack.
2. Feed the audio signal shown in table to the AUDIO IN
jack.
3. Put the unit in E-E or recording mode.
4. Make sure that the output level is value shown in table.
AUDIO CIRCUIT ADJUSTMENT
CHECKING OF E-E LEVEL
Measuring
AC milli-voltmeter
instrument
Mode
E-E/Record
Input signal
1kHz, –3.8 dBs
Test point
AUDIO OUT jack
Specification
–3.8 
±
 2dBs
1. Connect an AC milli-voltmeter to the AUDIO OUT jack.
2. Feed the audio signal shown in table to the AUDIO IN
jack.
3. Make the self-recording and playback of the signal.
4. Make sure that the output level is value shown in table.
CHECKING OF AUDIO RECORD LEVEL
Measuring
AC milli-voltmeter
instrument
Mode
Record/playback
Input signal
1kHz, –8.0 dBs
Test point
AUDIO OUT jack
Specification
–8.0 
±
 3dBs
CHECKING OF ERASE VOLTAGE AND OS-
CILLATION FREQUENCY
Measuring
Oscilloscope
instrument
Mode
Record
Test point
Full erase head
Control
T601
Specification
70 
±
 5kHz, 40Vp-p or greater

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