Sharp MZ-80B Service Manual page 23

• Trouble Shooting Chart
Problem 1: No picture appears.
No pioture
-1
N~
Check CPU board,
I NO
Check
CPU board.
i
Check
I
Check VR-2002
Check
Only
video
Check
02001, Q2002 and
r
raster f-----'
L
video ~
+12V power
r--
input signal.
vide0-40V power
appears.
YES
circuit.
supply,
supply.
Y~
Neither
L.
raster nor
picture NO
appears.
-1
Check CAT plug.
I
W
rl
Defective CAT.
~.
Check
CRT
heater.
YES
Check high
~
voltage at K,
Gl,G2and
G3 of CRT.
Problem 2: Sync operation remains ineffective.
N
n
Check CPU I
Neither
board.
r-
horizontaJ nor
vertical sync.
~.0~e
I
sync, -
~gnal?
operation is
ineffective.
-
Only vertical
YE S
sync. operation
is ineffective.
y
Only hOrizontal
. sync. operation
l.
is in.effective.
Problem 3: Raster is too narrow.
NO Chcek V-HOLD
VR~
, - - ~ _ i _ ~ ~ _ ~ _ ~ w _ i ~ _ ~ _ l t _ ~ ~ _ f _ ~ m _ ' ~ _ 4 _ ' ~~I!,
I
I~~.:::'·:~:::~·I
' "
.1
L '
_ ~ _ ~ _ g _ r _ ~ . _ a _ n _ d ~
of IC2001 (at pin I
YES (".')
normal? :
Is output
L.....::..:...... .-
YESl.. waveform of
IC2001 normal?
Problem 4: No sound comes out.
NO Agalfl set
correct program.
Is there
YES
j
audio
~.ignaP
NrO _ _ --'!
Check
CPU!
L~oilrd.
_-_ _ J
I
YES
Is input
signal of
IC2002 (at
pin@1
normal"?
NO
YES
- 21 -
iD2009, D2010
Q2007)
Cheek middle/
YES
high voltage
rectification
YES (D 2006. D 2009 and
n
Defective CRT.
FBT.!
'-----.
f-- Check AFC, )
' c l
Check
J-
NO
horizontal .
NO FBT circuit.
oscill",or
and
~
drive output
circuit.
~.-
. . . . . .
Check sync.
separation (D2001
and Q2003l.
Check integrating.
Circuit (R2030 to R2023,
and C2011 toC2013).
Check AFT circuit
(Check point
CD
output of
FBT, R2030, C2021 , R2033,
R2055 and C2055)
NO
Defective IC2001.
YES
,Check deflection coil (C2016L
Chceck VR,
I
R2050 and
I
C2043
--.J
NO
Is output
signal of IC2002 )-_ _
/at pin
(7))
normal?-
YES
Check C2053 and
J
speaker.