Troubleshooting - Sharp VC-GH61SM Service Manual

FLOW CHART NO.1 POWER TROUBLESHOOTING(1)
No power.
NO
Is the fuse good?
YES
Is the normal state restored when
NO
once unplugged power cord is
plugged again after several seconds?
YES
NO
Are AT 5V voltage line normal?
YES
NO
Are AT 5V and AT 12V lines normally?
FLOW CHART NO.2 POWER TROUBLESHOOTING(2)
In case of Fuse (F901) blown out.
Check for leak or short-circuiting of
primary circuit part (D901~906, Q901
~903, T901, C906, L901, D912 etc.),
replace defective parts.
FLOW CHART NO.3 POWER TROUBLESHOOTING(3)
In case of abnormal noise (sound).
Check for short circuit of rectifying diode of each rectifying circuit of secondary circuit
and check for shunt regulator circuit. (D934, D933, IC903, C9335~9336)
The fuse blows out even when it is
replaced with new one.
See FLOW CHART NO.2
POWER TROUBLESHOOTING (2)
<In case of Fuse (F901) blown out.>
Check for leak or short-circuiting
of primary circuit part
(D901~906, Q901~903, T901,
C906, L901, D912 etc.), replace
defective parts.
Check each rectifier circuits and
short-circuit of secondary circuit.
Check for short-circuit of rectifying
diode and circuit in each rectifying
circuit of secondary circuit.(D934,
D933, D932, D931)
FLOW CHART NO.4 POWER TROUBLESHOOTING(4)
In case of output voltage at low level.
Check whether the secondary side
photocoupler circuit operates normally. NO
(IC903,C9336,R930,R932,R933)
YES
Check whether the primary side
NO
photocoupler output control function
normally. (Q901 & Q902)
YES
Replace IC901.
FLOW CHART NO.5 SYSTEM CONTROL TROUBLESHOOTING
No power is turned on.
YES
NO
Does power control (H) signal at pin(96)
of IC701 change from "L" to "H" level?
YES
NO
Does the base voltage of Q966
change from about 12.6V to 11.8V?
YES
NO
Is voltage of 12V sent out from the
collector of Q966 transistor?
YES
NO
Does the base voltage of Q961
change from about 5.5V to 6.2V?
YES
NO
Is voltage of 5V sent out from the
emitter of Q961 transistor?
Check the circuit and replace
defective parts. (IC901, IC903, etc.)
Check the circuit and replace
defective parts. (IC901, IC903, Q902,
T901, etc.)
Check IC701.
Check line between Q966, Q967 and
IC701.
Check peripheral circuit of or Q966
and AT 12V line.
Check line between emitter of or Q966
and base of Q961.
Check peripheral circuit of Q961 and
AT 5V line.