Sharp VC-H982U

39
VC-A582U
VC-A582U(A)
VC-H982U
7. TROUBLESHOOTING
FLOW CHART NO.1 POWER TROUBLESHOOTING(1)
No power
Unplug the AC power cord. Replug it a few minutes later.
See FLOW CHART NO.2 POWER TROUBLE SHOOTING(2)
YES
YES
YES YES
YES
NO
NO
NO
NO
NO
Is the fuse good?
Replace fuse.
Are AT 5V voltage line normal?
Check primary circuit.
Are AT 44V, AT 12V, -24V, AT 18V and filament voltage lines normal?
Check each rectifier circuits and short-circuit of secondary circuit.
Is "H" level applied at pin(1) of IC701?
Check Q905 and P-FAIL(L) signal line etc.
Check system control circuit (IC701) and cam switch circuit.
FLOW CHART NO.2 POWER TROUBLESHOOTING(2)
In case of Fuse(F901) blown out.
Replace F901, Q901 and Q902, check D921~D925 as a result of check, if poor, replace at the same time.
Check short-circuit or leak of D905 thru to D909, D918 and secondary circuit.
FLOW CHART NO.3 POWER TROUBLESHOOTING(3)
In case of abnormal noise(sound)
Check D905 thru to D909 and D918.
YES
YES
YES
NO
NO NO
FLOW CHART NO.4 POWER TROUBLESHOOTING(4)
In case of output voltage at low level.
Check the D914, Q903 and Q904.
Replace D914, Q903 and Q904.
Check IC901.
Replace IC901
Check short-circuit or leak of T901.
Replace T901.
Check primary circuit,Q901,Q902, C907 thru to C909 and C930.
FLOW CHART NO.5 TIMER(1) TROUBLESHOOTING
The flourescent display tube fails light up.
Is the supply voltage of 5V feed to pin (18) of IC801?
Check AT 5V line.
Is the supply negative voltage of-24V feed to pin(16) of IC801?
Check negative voltage line and power circuit.
Is there 500kHz oscillation at pins(19) and (20) of IC801?
Check FL801 and IC801.
Is filament voltage applied between (1)/(2) and (31)/(32) of the flourescent display tube?
Also negative voltage applied between these pins and GND.
Check power circuit and peripheral circuit of D952.
Does the flourescent display tube function?
Replace IC5001.
Check for cracks on the flourescent display tube.
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO