Sharp VT-G14 - Page 58

58
VT-G14
VT-G21
YES
YES
YES
YES
YES
YES
YES
YES
NO
FLOWCHART NO. 1-11
DRUM SERVO TROUBLESHOOTING
Drum servo does not function.
Is there 16MHz
oscillation at pins (38)
and (39) of IC7701 ?
Is there the durm PG
signal at pin (86) of
IC7701 ?
Is there the reference
signal (V-sync.) at pin
(84) of IC7701 ?
Is there the head
switching pulse at pin
(18) of IC7701 ?
In REC modeIn PB mode
Is there the drum control
output at pin (78) of
IC7701 ?
Is there the durm FG
signal at pin (87) of
IC7701 ?
Check FG and PG signal
at pins (3) and (5) of the
connector ME and the
drum motor.
Check the signal line of
drum PG.
Is there the drum control
voltage applied to pin (7)
of connector AD ?
Check the composite
sync. signal at pin (14) of
IC2201, Q2201, Q2202
and Q7706 all the way up
to pin (84) of IC7701.
Check the signal line
between pin (7) of AD
and pin (78) of IC7701.
Check and replace the
drum motor.
See FLOWCHART NO.
1-8.
NO
NO
NO
NO
NO
NO
NO
Replace IC7701.
Check X7701, C7705
and C7706.
Replace IC7701.
Is pin (76) of IC7701 in
high impedance ?