Hitachi C43-FD2000, Service Manual

Page: 54 / 131

SIG-POWER failure:
Sub-Power check flow
F902 blown?
No
Yes
Shutdowned by PROTECTION:
Check I905 and short-circuit of STBY5V with
higher voltage.
POWER-SUP
PWB
POWER-SUP PWB
Over current in live side.
Check I901, T901 and circuit connected to I901(3)
While the startup
V > 20V at I901(3)
transiently
Check D931, D932, C934, E903,
E904 and short-circuit of
SIG-POWER cold side.
While the startup,
V>0.5V at I903(1)
transiently
V < 5V at I901(3)?
(Vin pin)
No power for I901,
Check I901, D907, R907, R908 and etc.
SIG-POWER Feedback circuit not function.
Check D930, I902, D933, E905 and etc.
Over voltage of STBY5V
power on
0.8V
0V
I903(1)
Yes
No
POWER-SUP PWB
POWER-SUP PWB
Yes
POWER-SUP PWB
No
POWER-SUP PWB
become higher than 10V once
15V
0V
I901(3)
5V
power on
Note: Vin also becomes less than 5V if shutdowned by protection.
Check I905(5) first!
Yes
POWER-SUP PWB
POWER-SUP PWB
No
20V
15V
power on
10V
0V
POWER-SUP PWB