Sharp VC-MH815HM/LM

41
VC-MH705HM/LM VC-MH815HM/LM,MH85HM VC-MH715HM,MH835HM
7. ELECTRICAL TROUBLESHOOTING
FLOW CHART NO.1 POWER TROUBLESHOOTING(1)
No power.
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.>
YES
YES
YES
NO
NO
NO
NO
Is the fuse good?
Is the normal state restored when
once unplugged power cord is
plugged again after several seconds?
Check for leak or short-circuiting
of primary circuit part
(D901~906, Q901~903, T901,
C906, L901, D912 etc.), replace
defective parts.
Are AT 5V voltage line normal?
Are AT 5V and AT 12V lines normally?
Check each rectifier circuits and
short-circuit of secondary circuit.
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 for short-circuit of rectifying
diode and circuit in each rectifying
circuit of secondary circuit.(D934,
D933, D932, D931)
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)
FLOW CHART NO.4 POWER TROUBLESHOOTING(4)
In case of output voltage at low level.
Check whether the secondary side
photocoupler circuit operates normally.
(IC903,C9336,R930,R932,R933)
Check the circuit and replace
defective parts. (IC901, IC903, etc.)
NO
YES
Check whether the primary side
photocoupler output control function
normally. (Q901 & Q902)
Check the circuit and replace
defective parts. (IC901, IC903, Q902,
T901, etc.)
NO
YES
Replace IC901.
YES



YES



YES



NO
NO
NO
FLOW CHART NO.5 SYSTEM CONTROL TROUBLESHOOTING



No power is turned on.



Does power control (H) signal at pin(96)
of IC701 change from "L" to "H" level?
Check IC701.
Does the base voltage of Q966
change from about 12.6V to 11.8V?
Check line between Q966, Q967 and
IC701.
Is voltage of 12V sent out from the
collector of Q966 transistor?
Check peripheral circuit of or Q966
and AT 12V line.
YES



YES



YES



NO
NO
Does the base voltage of Q961
change from about 5.5V to 6.2V?
Check line between emitter of or Q966
and base of Q961.
Is voltage of 5V sent out from the
emitter of Q961 transistor?
Check peripheral circuit of Q961 and
AT 5V line.
Check peripheral circuit for poor
soldering.
www.freeservicemanuals.info
6/17/2019
Digitized in Heiloo the Netherlands
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