ViewSonic P90F - Troubleshooting Section 3

30
SECTION 3
NO
LED Green
No Raster
Is DC Voltage at Pin2 of
FBT Pro
p
er
(
80 V A
pp
rox.
)
NO
YES
Is the voltage 6.3V at
heater?
NO
YES
Check Q121 output
300 V
p
-
p
a
pp
rox.
Check I101 pin 2 > 2.5V
NO
Check OVP CKT setting
build by Q114,115,116
Is the voltage at collector of
Q
433
p
ro
p
er ?
YES
NO
Go to SECTION 4 No
raster ,but High Voltage
exist
Check SMPS DC O/P
(
SECTION 1
)
Check S.M.P.S
(SECTION 1)
Check P902 connection
OK ?
YES
Check P904 connection
OK ?
YES
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Confidential – Do Not Copy
P90f-1