Service manual

34
SECTION 7
SECTION 8
No OSD
Check IIC Bus (P903A to
P904). Press Enter key,
there should be a
sequential pulse appear
for IIC communication
I903 Vdd = 5V ?
YES
Check I903 and its
peripheral circuit
YES
No video
Raster exist
Check OSD (I903)
Check if Contrast is too
low ?
YES
NO
Check R,G,B at
CDT socket
YES
Check I904 R,G,B output
NO
Check 82V, 190V for
I904 and their peripheral
CKT
YES
Replace I904
YES
Check I904 input
NO
Check R,G,B signals at
P901
NO
Check IIC Bus
(P903A to P904).
Press Enter key ,
there should be a
sequential pulse
appear for IIC
communication
ViewSonic Corporation
Confidential – Do Not Copy
P90f-1