Sharp LC-28HM2E (serv.man2) Service Manual ▷ View online
41
LC-28HM2
AN-28SP2
TROUBLE SHOOTING TABLE
(Continued)
System does not star
t up.
No
Does system star
t up in the
process adjustment mode?
Ye
s
“0”
What is
“LAMP NG”
count?
“5”
Replace f
aulty lamp
.
Ye
s
What is the v
oltage at pin (2) of
IC2004?
No
No
Chec
k displa
y side po
w
er unit.
Chec
k pins (3) and (17) of P2001
and its per
ipher
al circuits
.
Is the v
oltage at pin (11) of P2001
measured at 4.2V or higher when
b
lue LED is ON?
Red LED lights up from the
beginning.
Blue LED lights up first, b
ut soon
red LED lights up
.
Ye
s
Is the v
oltage 0V at pin (27) of
IC2004?
3.75~5 V
2~3.75 V
1~2 V
0~1 V
Chec
k system cab
le
.
Nor
mal oper
ation
Chec
k output at pin (21)
of P701.
Chec
k output at pin (3)
of P2001.
42
LC-28HM2
AN-28SP2
TROUBLE SHOOTING TABLE
(Continued)
No po
wer suppl
y
Chec
k LED lamp color
.
Displa
y - Green,
A
VC system - Green
(Nor
mal)
Displa
y
- Green,
A
VC system - Red
(F
aulty condition)
Press po
w
e
r
b
u
tton of remote
controller
.
Chec
k po
w
e
r
supply at A
VC
system.
Displa
y
- Red, A
VC
system - Green
(F
aulty condition)
Press po
w
e
r
b
u
tton of remote
controller
.
Switch off the
po
w
e
r.
Chec
k IC2004.
Displa
y - Red, A
VC
system - Red
(Same as stand-b
y
Press po
w
e
r
b
u
tton of remote
controller
.
Star
t up with the
displa
y process
adjustment mode
.
Chec
k po
w
e
r and
GND of IC2004.
Chec
k
pins (5)
and (6) of IC2004.
Is pin (19) (MPO
W)
of IC2004 at high
le
v
e
l?
Chec
k lamp
condition.
Is there an
y brok
en
lamp?
If it is lik
ely that
lamp error count is
tr
igger
ing alar
m,
reset the lamp error
counter
.
Chec
k CCKM line
per
ipher
als of both
displa
y and center
.
Chec
k the system
cab
le
.
Displa
y LED is
OFF
.
Is +5V a
v
ailab
le at
pin (5) of P2001?
Is +5V a
v
ailab
le at
pin (2) of P3601 on
RC unit?
Chec
k LED and
per
ipher
als on RC
unit.
Chec
k RC PWB
fur
nace or +5V
po
w
e
r line
.
A
VC system LED is
OFF
.
Is there LED
VCC
output from
monitor?
Chec
k LED per
ipher
als on front
ter
m
inal unit.
Is +5V a
v
ailab
le at pin (37) of SC404 and
pin (13) of both D501 and SC401?
No
No
Is specified v
oltage
output a
v
ailab
le
from displa
y po
w
e
r
unit?
Ye
s
Is pin (19) (MPO
W)
of IC2004 at high
le
v
e
l?
Ye
s
Is specified v
o
ltage
output a
v
ailab
le
from DC/DC unit?
Ye
s
Chec
k the
per
ipher
al circuits
of X2001.
No signal
Chec
k the
per
ipher
al circuits
of IC2004.
No
No
Ye
s
Ye
s
Y
e
s
Ye
s
No
Change
occurs
.
No change
occurs
.
No change
occurs
.
No screen
appears
.
No screen
appears
.
No
prob
lem
Signal
present
The set
star
ts up
.
Screen
appears once
,
b
u
t disappears
soon.
When CCKM
per
ipher
a
ls are
not f
aulty
.
<Ref
erence>
DC/DC PWB output
+3.3V
, +5V
, -4.5V
,
-15V
, +28V
, +9V
Displa
y po
w
e
r unit output
+13V
, 5V
Chec
k DC/DC unit.
No
Chec
k displa
y
po
w
e
r unit.
If A
C
po
w
e
r connection is nor
mal, it is
possib
le that displa
y po
w
e
r unit is
faulty
.
It is also possib
le that +5V line is shor
t-
circuited and activ
ating the protection
circuit f
o
r the displa
y po
w
e
r unit.
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.
44
LC-28HM2
AN-28SP2
TROUBLE SHOOTING TABLE
(Continued)
No sound
Ye
s
No
Does output icon show
headphone when volume
key is operated?
No sound from speaker
No
Is pin (15) of SC401 at
high level?
No
Check headphone plug
peripherals on front
terminal unit.
Check the peripherals
of speaker connector
terminal.
Ye
s
No
Does output icon show
lineout when volume key
is operated?
Monitor output in main menu is set to
"variable". Switch it to "fixed" or set video 3
to "input".
No
Ye
s
Are there normal outputs
at pins (52) and (54) of
IC401?
Check the peripherals
of IC401.
No
Ye
s
Are there normal outputs
at pins (1) and (7) of
IC306?
Check IC306 and its
peripherals.
Check rear terminal unit.
It is also possible that
display has problem.
No sound from headphone
No
Ye
s
Does output icon show
headphone when volume
key is operated?
Check headphone plug
peripherals on front
terminal unit.
Ye
s
Ye
s
Is pin (14) of IC505 at
high level?
Headphone is muted.
Check the peripherals
of IC505 and D306.
No
Ye
s
No
Are there normal audio
outputs from pins (7) and
(18) of IC301?
Is pin (9) of IC301 at
low level?
No
Ye
s
Is B of Q303 at high level?
Are there normal audio
inputs at pins (2) and
(23) of IC301?
No
Check the peripherals
of IC401.
Check IC307, Q309
and their peripherals.
Ye
s
Check C383 and the
peripherals of IC704.
Ye
s
Check the peripherals
of IC301.
No
Ye
s
Are there normal audio
outputs from pins (1) and
(7) of IC305?
Check the peripherals
of IC305.
Check the peripherals of
C2401 and C2402 on
front terminal unit.
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