Troubleshooting - Sharp DV-550U Service Manual

11. TROUBLESHOOTING

FLOW CHART NO.1 POWER TROUBLESHOOTING(1)
No power.
Unplug the AC power cord.
Replug it a few minutes later.
Is the fuse good?
Yes
Is AT 5V voltage line normal?
Yes
Are AT 8V,AT 12V,AT -30V and filament voltage
lines normal?
FLOW CHART NO.2 POWER TROUBLESHOOTING(2)
Replace F9001,Q9007,Q9010 and D9020, check
D9016 as a result of check, if poor, replace at the
same time.
FLOW CHART NO.3 POWER TROUBLESHOOTING(3)
In case of abnormal noise(sound).
Check D9024,D9005,D9006,D9007 and D9008.
FLOW CHART NO.4 POWER TROUBLESHOOTING(4)
In case of output voltage at low level.
Check the D9014,Q9006 and Q9009.
Yes
Check D9020.
Yes
Check D8022 and R8030.
Check short-circuit or leak of T901.
Yes
Check primary circuit,Q9007,Q9010,C9023,C9024,
C9027,D9011 and D9014.
FLOW CHART NO.5 DISPLAY TROUBLESHOOTING
The fluorescent display tube fails light up.
Is the supply voltage of 5V fed to pin(18) of
IC5001?
Yes
Is the supply negative voltage of -30V fed to pin
(16) of IC5001?
Yes
Is there about 4MHz oscillation at pins(19) and
(20) of IC5001?
Yes
Is filament voltage applied between (1)/(2) and
(61)/(62) of the fliorescent display tube?
Also negative voltage applied between these pins
and ground.
Yes
Dose the flourescent display tube function?
Yes
Replace IC5001.
See FLOW CHART NO.2 POWER TROUBLE-
SHOOTING(2)
No
Replace fuse.
No
Check primary circuit,D9007,L9001,C9019,C9014
and C9013.
No Check each recifier circuits and short-circuit of
secondary circuit.
In case of Fuse(F9001) blown out.
Check short-circuit or leak of D9005 thru to D9008
and secondary circuit.
No
Replace D9014,Q9006 and Q9009.
No
Replace D9020.
No
Replace T9001.
No
Check AT 5V line.
No Check negative voltage line (AT -30V) and power
circuit.
No
Check FL5001 and IC5001.
No Check power circuit and peripheral circuit of
D5001.
No
Check for cracks on the flourescent display tube.
11-1
No
DV-550U