Electrical Adjustments - Sanyo M7700L Service Manual

ELECTRICAL ADJUSTMENTS
REQUIRED EQUIPMENTS
VTVM (two sets)
Frequency Counter
Dummy Load (470 k-ohm)
Dualtrace Synchroscope
Test Tapes
* 3kHz test Tape (TEAC MTT-111) for Tape Speed
Adjustment
* 8kHz Test Tape (TEAC MTT113C) for Head Azimuth
Adjustment
* 1kHz Test Tape (TEAC MTT-112B) for Playback Gain
Adjustment
DC Constant-Voltage Regulator
Alignment Tool
Prior to the Electrical Adjustments, set the unit and
the measuring instruments as follows:
Function Switch 2.2... 0.0... 00 ees TAPE
Mode Switch............. 0000s STEREO
Input Select Switch ............. to REC/PB terminal
Beat Cancel Switch .......... 0.0000 eee ee es 1
DC Constant-Voltage Regulator Output ....... 7.5V DC
NOTE:
1. Perform each adjustment in the described order.
2. Obtain the output from the R/P DIN socket.
3. Supply 7.5 V DC from the constant-voltage regulator to
the unit.
4. When obtaining the output from the R/P DIN socket,
connect the leads noting the terminal numbers as
illustrated.
Ground
Right Channel Output
Right Channel Input
Left Channel Input Left Channel Output
TAPE SPEED ADJUSTMENT
1.
2
Remove the battery compartment lid and connect the
frequency counter to the left or right channel output
terminals of the R/P DIN socket as illustrated.
Frequency Counter
3,000Hz (+3%)
Dummy Load
470 k-ohm
Insert the 3 kHz test tape (Example: TEAC MTT-111) into
the compartment and play it back.
Adjust the tape speed by turning the potentiometer (P801)
on the Governor Circuit P.C.Board with an alignment tool to
obtain 3,000 Hz (43%) on the frequency counter. See the
illustration below.
Tape Speed Adjusting Hole
HEAD AZIMUTH ADJUSTMENT
ile
Remove the cassette compartment lid. Connect a VTVM and {
a dualtrace synchroscope to the R/P DIN socket as
illustrated.
Synchroscope
x.)
dc) Dummy Load
470 k-ohm
Dummy Load
470 k-ohm
Set the synchroscope as follows:
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Insert the 8 kHz test tape (Example: TEAC MTT-113) into
the compartment and play it back.
Slowly turn the azimuth adjusting screw until the
amplitudes of both channel output wave forms become
maximum and the wave forms overlap as well as possible in
the maximum condition of the VT VM as illustrated.
R/P Head