ViewSonic P90F Service Manual page 38

SECTION 7
No video
Raster exist
Check OSD (I903)
Check if Contrast is too
low ?
Check R,G,B signals at
P901
SECTION 8
ViewSonic Corporation
NO
YES
NO
No OSD
Check IIC Bus (P903A to
P904). Press Enter key,
there should be a
sequential pulse appear
for IIC communication
I903 Vdd = 5V ?
Check I903 and its
peripheral circuit
YES
Check IIC Bus
(P903A to P904).
Press Enter key ,
there should be a
sequential pulse
appear for IIC
communication
YES
YES
34
Check R,G,B at
CDT socket
NO
Check I904 input
YES
Check 82V, 190V for
I904 and their peripheral
CKT
YES
Check I904 R,G,B output
NO
Replace I904
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