Sharp LC-28HM2, Service Manual

Page: 14 / 128

14
LC-28HM2
AN-28SP2
Æ
Specific faults and countermeasures
Symptom
P
ossib
le cause
P
ossib
le f
ault location
Counter
measure
System cab
le and connector
.
P
anel side decoder IC sync
output and the circuits to f
ollo
w
.
P
anel side decoder IC
.
PC I/F Unit. System cab
le and connector
.
A
VC System:
TXD_M and RXD_M
line Monitor
: MTXD and MRXD
line
.
System cab
le and connector
.
SMPO
W line and per
ipherals
.
System cab
le and connector
.
CCKM line and per
ipherals
.
Shor
t-circuit in the per
ipherals of
po
w
er line
P
o
w
er line shor
t-circuit mode with
such troub
le as anti-static de
vice
b
ur
nout.
Same as left.
Replace cab
le or connector
and chec
k connection.
Chec
k the circuits f
ollo
wing the
sync output of the decoder IC
.
P
anel side decoder IC
.
Replace PC I/F Unit. Replace cab
le or connector
and chec
k connection.
Chec
k the line in question.
Replace cab
le or connector
and chec
k connection.
Chec
k the line in question.
Replace cab
le or connector
and chec
k connection.
Chec
k the line in question.
Chec
k the line in question.
Chec
k diodes and others
betw
een signal line and po
we
r
line on the ter
minal board.
Replace PC I/F Unit.
Cautions:
»
With this model, neither the displa
y unit nor the A
VC system can perf
or
m the independent oper
ation in the nor
mal mode
.
»
Star
t-up ma
y not be possib
le in some cases because of the lamp f
ailure or other cause
. In this case
, star
t up with the process adjustment
mode of the monitor unit independently
, and initializ
e the times of lamp f
ailures recorded.
(See the Ser
vice Man
ual.)
T
o simply chec
k the
times of lamp f
ailures
, ref
er to the process adjustment mode page 1 LAMP NG CHECK.
Video signal (sync signal) is not f
ed into the panel control
G/A (Detected b
y sync
signal). T
ransmission f
ailure between
displa
y and A
VC system.
F
ault in control line from the
displa
y unit to tur
n on the
po
w
er at the A
VC system.
F
ault in pow
er star
t-up chec
k
line and per
ipher
als
.
A
VC system s
witching po
w
er
cut-off b
y o
v
er
load protection
circuit, or b
ur
nout fuse
.
PC I/F Unit G/A damage
.
Blue screen. No bac
klight illumination, although both displa
y
LED and A
VC system LED are lit in g
reen.
When the po
w
er is s
witched on, the
displa
y
unit
’s
po
w
er rela
y is tur
ned on, b
ut the A
VC system po
w
er
rela
y is not tur
ned on in succession.
When the po
w
er is s
witched on, the
displa
y
unit
’s
po
w
er rela
y is activ
ated, and then the A
VC system
po
w
er rela
y is tur
ned on once b
ut it is tur
ned off
immediately
. The po
w
er is tur
ned on when the
process adjustment is entered b
y displa
y b
utton
oper
ation while k
eeping connection betw
een the
displa
y
and the center
.
When the po
w
er is s
witched on, the
displa
y
unit
’s
po
w
er rela
y is activ
ated, and then the A
VC system
po
w
er rela
y is tur
ned on once b
ut it is tur
ned off
immediately
.
The po
w
er is not tur
ned on when tr
ying
to enter the process adjustment b
y displa
y b
utton
oper
ation while k
eeping connection betw
een the
displa
y
and the center
.
No OSD appear
ing (Remote control is oper
ativ
e).