Sharp MZ-80B - 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~_~_lt_~~_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, )
'cl 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.