7. 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.
Check the circuit and replace
defective parts. (IC901, IC903, etc.)
NO
YES
Check whether the primary side
photocoupler output control
function normally.
Check the circuit and replace
defective parts. (IC901, IC903, Q902,
T901, etc.)
NO
YES
Replace IC901.
FLOW CHART NO.5 SYSTEM CONTROL TROUBLESHOOTING(1)
No power is turned on.
Does power control (H) signal at
pin(76) of IC701 change from "L" to
"H" level?
Check IC701.
Does the base of Q967 change from
"L" to "H" level?
Check lines between the Q967 and
all the way up to IC701.
Is about 4.4V applied at the base
of Q968?
Check Q967, Q968, and Q961.
Is 12V at the collector of Q968?
Check line between Q968 and
all the way up to AT 12V line.
Is 12V at the emitter of Q968?
Check peripheral circuits for poor
soldering.
Check AT 12V line.
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
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