Sharp VC-V50S, Руководство по обслуживанию

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VC-V50S
VC-V80T
VC-V91T
36
FLOW CHART NO.5 SYSTEM CONTROL TROUBLESHOOTING(1)
No power is turned on.
Does power control (H) signal at pin(48) of IC801 change from "L" to "H" level?
Check IC801.
Does the base of Q928 change from "L" to "H" level?
Check lines between the Q928 and all the way up to IC801.
Is about 4.4V applied at the base of Q927?
Check Q921, Q922, Q923, Q927 and Q928.
Is 5V at the collector of Q927?
Check line between Q927 and all the way up to AT 5V line.
Is 5.2V at the emitter of Q927? Check peripheral circuits for poor soldering.
Check AT 5V line.
YES YES YES YES YES
NO NO NO NO NO
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, IC921, etc.)
NO
YES
Check whether the primary side photocoupler output control function normally.
Check the circuit and replace defective parts. (IC901, IC921, Q902, T901, etc.)
NO
YES
Replace IC901.
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 (L902, D901~905, D907~908, Q901~902, T901, C907, etc.), replace defective parts.
Are AT 5V voltage line normal?
Are AT 5V and M 12V lines normal?
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 (L902, D901~905, D907~908, Q901~902, T901, C907, etc.), replace defective parts.
Check for short-circuit of rectifying diode and circuit in each rectifying circuit of secondary circuit. (D921, 922)
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. (D921, D922, IC921, C927~928)
7.
TR
OUBLESHOO
TING