STR-KIV300 - Sony Audio Service Manual (repair manual). Page 20

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STR-KIV300
20
 SECTION 5
TROUBLESHOOTING
Power Check Flow (1/2)
Check that the output voltages of the switching regulator
(SWR1) are the following value.
CN301 pin 5: 12 V (ICUNSW12V)
CN301 pin 6: 12 V (UNSW12V)
CN301 pin 7: 12 V (FL12V)
Check that the following fuses and thermistor are not damaged.
F5301, F5303
Ye
s
Ye
s
C
heck 
each 
vol
tage w
ith r
ef
er
ence 
to the 
sc
hematic 
diagrams,
and check 
that ther
e is
 no 
pr
oblem 
in them.
Check the 
related IC 
on 
the 
MB1306 
board.
Ye
s
C
heck 
the 
fo
llow
ing 
pow
er
 contr
ol 
si
gnal 
in the power on state.
(Nor
mally voltage: 
+3
.3 
V)
MB1306 b
oa
rd
 IC
801 pin 
36 
to 
38
(PCON
T1 to
 PCON
T3)
Pin 25 
(PCONT
_F
L)
Ye
s
The power is turned on.
A
No
Yes
Pr
otect 
mode happened “PROTECT”
dis
play appear
on 
fluor
es
cent 
tube.
No
Ye
s
C
heck 
that har
nes
s is
 ins
er
ted nor
m
ally 
at 
CN101
Remove harness 
of 
CN
101, CN
4, 
FFC 
CN
3505.
Measure switchi
ng supply 
board 
CN
101 
pin1, 
pin2
(normal voltage 
30V)
Ye
s
Ye
s
AMP boar
damage. 
Exchange the 
complete AMP 
board.
Check 
that harness is 
inse
rted normally at 
CN
301 
and
C
N
5301. 
When har
nes
is 
ins
er
ted 
nor
mally, 
exchange the
switching regulator (SWR1).
No
Exchange the 
damaged f
us
or 
thermistor. 
Exchange the
complete MB1306 board, when the power is not turned on,
even if
 you 
exchange f
us
es
.
No
Pow
er
 s
upply IC
 is
 damaged. Exchange 
the 
pow
er
 s
upply IC.
No
Exchange 
the 
complete MB1306 board.
No
No
Ins
er
t nor
mally the har
nes
s and 
pow
er
 O
N
 again.
No
Sw
itching s
upply 
boar
damage. Exchange the 
complete
sw
itching s
upply 
boar
d. 
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