Read Sharp VC-MH834 (serv.man3) Service Manual online
41
VC-M314HM
VC-MH834HM
VC-MH834HM
7. ELECTRICAL
TROUBLESHOOTING
FLOW CHART NO.1 POWER TROUBLESHOOTING(1)
No power
Unplug the
AC power cord.
Replug it a few minutes later
.
See FLOW CHAR
T
NO.2 POWER
TROUBLESHOOTING(2)
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
Is the fuse good?
Replace fuse.
Is
A
T
5V voltage line normal?
Check primary circuit.
Are A
T
42V
, A
T
23V
, A
T
12.6V
,
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 peripheral circuits Q9603
and P-F
AIL
(L) signal line etc.
Check system control circuit
(IC701).
FLOW CHART NO.3 POWER TROUBLESHOOTING(3)
In case of abnormal noise(sound)
Check D9603, D9604, D9605
and D9606.
The D9603, D9604, D9605 and
D9606 as a result of check
if poor the replace.
NO
FLOW CHART NO.2 POWER TROUBLESHOOTING(2)
In case of Fuse(F901) blown out.
Replace F901, Q901 and R904,
check D910, D91
1, D912 and
D913 as aresult of check, if poor
,
replace at the same time.
Check short-circuit or leak of
D9603, D9604, D9605, D9606
and secondary circuit.
FLOW CHART NO.5 TIMER TROUBLESHOOTING (1)
The LCD display fails to light up.
Is the supply voltage of 5V fed to
pin(37) of IC8001?
Check STBY
5V line.
Is the supply voltage of 3.4V
, 1.7V
feed to pin(38) and pin(39) of IC8001?
Check pin(38), (39) of IC8001
and peripheral circuits.
Is it possible to confirm signals
LCD RESET
, LCD CS, LCD CLOCK
and LCD DA
T
A
on the pins(36),
(42), (43) and (44) of IC8001?
Are the segment signals
supplied to the LCD display
(LC8001) fromthe driver IC
(IC8001)?
Check peripheral circuit of pin(41)
of IC8001.
Check that the LCD display is
free from damages such as
crack.
Replace IC8001.
YES
YES
YES
YES
NO
NO
NO
NO
NO
YES
YES
YES
NO
NO
NO
FLOW CHART NO.4 POWER TROUBLESHOOTING(4)
In case of output voltage at low level.
Check peripheral circuits IC901,
IC9601, C9613, R9608, R9609,
R9610 and R961
1.
The IC901, IC9601, C9613, R9608,
R9609, R9610 and R961
1 as a result
of check, if poor the replace.
Check IC901 and peripheral
circuits.
Replace Q902.
Check short-circuit or leak of
T901.
Replace T901.
Check primary circuit and peripheral
circuit of Q901 and Q902.
Check the signal line between
IC701 and IC8001.
YES
IC8001 present?
Is the OSC signal at pin(41) of
Click on the first or last page to see other VC-MH834 (serv.man3) service manuals if exist.