Sharp 13VT-L200 Service Manual page 46

TAKE-UP REEL PULSE GENERATOR TROUBLESHOOTING
No reel sensor pulse appears.
Insert the cassette, and
put the unit in FF or REW
mode.
Are there the take
about
up/supply reel pulses at
4.5Vp-p
the collectors of
D7702/D7703.
Replace the take
up/supply reel sensors
D7702/D7703.
HEAD SWITCHING PULSE TROUBLESHOOTING
No head switching pulse.
4.2
Is the drum motor
D-PG
0
rotating?
4.4
D-FG
0
Are the drum PG and
drum FG signal inputted
to pins (86) and (87) of
IC7701, respectively?
Are there the drum PG
and drum FG Signals at
pins (3) and (5) of
connector AD?
Check the harness AD-
ME and the drum motor
unit.
FLOW CHART NO.1-7
NO
Check between D7702
YES
and pin (80) of IC7701,
between D7703 and pin
(79) of IC7701.
NO
FLOW CHART NO.1-8
NO
See FLOW CHART NO.
1-9.
YES
Check pin (18) of IC7701
YES
and signal line of head
switching pulse.
NO
Check all the way up to
YES
pins (86) and (87) of
IC7701.
NO
DRUM MOTOR TROUBLESHOOTING
The drum motor fails to run.
Is the voltage more than about
NO
2.6V applied at pin (1) of ME
connector.
YES
NO
Is 5V at pin (7) of ME connector?
YES
NO
Is 12V at pin (4) of ME connector?
YES
Check/replace the drum motor.
The drum motor runs only for a few seconds.
NO
Is drum PG signal at pin (5) of
ME connector?
YES
NO
Is drum PG signal at pin (86) of
IC7701?
YES
NO
IS H.SW. pulse at pin (18) of
IC7701?
YES
Check pin (76) of IC7701.
FLOW CHART NO.1-9
Check between the ME socket
and pin (78) of IC7701, and
between the ME socket and pin
(76) of IC7701.
Check the AT 5V line.
Check the AT12V line.
Check the drum motor.
Check between the ME
connector and all the way up to
pin (86) of IC7701.
Check or replace IC7701.