Read Sharp LC-28HM2E (serv.man2) Service Manual online
43
LC-28HM2
AN-28SP2
TROUBLE SHOOTING TABLE
(Continued)
No picture and no sound
No
Ye
s
Check IC703 output (3.3V) and its
peripherals, IC701 output (5V) and
its peripherals, and IC7005 output
(3.3V) and its peripherals.
Also check IC705, Q715 and their
peripherals.
Are there normal outputs of +31V,
+9V and +5V at secondary side of
T701?
Is display power interrupted?
Enter process adjustment mode at
display side.
Ye
s
Check R503, R504 and system
connector peripherals on rear
terminal unit.
No
Are F704 and F705 normal?
No
Is there short-circuit in loading
section with F704 and F705
removed?
No
Ye
s
Replace F704 and F705.
Ye
s
Is AVC system side switching
regulator making normal outputs of
PC3.3V, PC2.5V, PC5V, 12V, 16V
and 5V?
Ye
s
Is there normal +9V output at E of
Q715?
Are the outputs of PC3.3V, PC2.5V
and PC5V out of spec?
Ye
s
It is possible that PC I/F unit (CPCi-
0040CE11) has internal problem.
Ye
s
No
Check IC705, Q715,
L701 and their
peripherals.
Check IC703 output
(3.3V) and its
peripherals, IC701
output (5V) and its
peripherals, and
IC7005 output (3.3V)
and its peripherals.
Is only 16V output out of spec?
Ye
s
Check the peripherals of IC9701.
Is only 5V(D) output out of spec?
Ye
s
Check 5V(D) line.
No
No
No
No
Is 12V output out of spec?
No
Is signal waveform normal at
primary side of T701?
Ye
s
Check secondary side loading of
T701.
No
Check IC705, Q715 and their
peripherals as well as primary side
of T701.
No
Check IC702, Q702, L701 and
their peripherals.
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