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SECTION 7
SECTION 8
No OSD
Check I
2
C Bus (P903A
to P904). Press Enter
key, there should be a
sequential pulse appear
for I
2
C 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
Check I904 R,G,B input
NO
Check 82V, 193V for
I904 and their peripheral
CKT
NO
Replace I904
YES
Check I904 output
YES
Check R,G,B signals at
P901
NO
NO
Check
I901
ViewSonic Corporation
34
Confidential – Do Not Copy
A
9
0f+-1
Summary of Contents for A90f+ 1
Page 57: ...12 PCB Layout ViewSonic Corporation 54 Confidential Do Not Copy A90f 1...
Page 58: ...VIDEO PWB 0414 ViewSonic Corporation 55 Confidential Do Not Copy A90f 1...
Page 59: ...KEY CONTROL PWB 0488 ViewSonic Corporation 56 Confidential Do Not Copy A90f 1...
Page 60: ...MAIN BOARD 13 Schematic Diagrams ViewSonic Corporation 57 Confidential Do Not Copy A90f 1...
Page 61: ...VIDEO ViewSonic Corporation 58 Confidential Do Not Copy A90f 1...
Page 62: ...KEY CORTROL ViewSonic Corporation 59 Confidential Do Not Copy A90f 1...
Page 63: ...POWER SUPPLY CKT ViewSonic Corporation 60 Confidential Do Not Copy A90f 1...
Page 64: ...MCU CONTROL CKT ViewSonic Corporation 61 Confidential Do Not Copy A90f 1...
Page 65: ...Time Base DeflectionCKT ViewSonic Corporation 62 Confidential Do Not Copy A90f 1...
Page 66: ...H V DYNAMIC FOCUS CKT ViewSonic Corporation 63 Confidential Do Not Copy A90f 1...
Page 67: ...14 Exploded Diagram ViewSonic Corporation 64 Confidential Do Not Copy A90f 1...