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5.
Video is defective
﹒
No video display
Does the entire screen
light up?
Are the voltage on
heater, G1,G2 of CRT
socket normal?
Are the waveform of the
terminal BK,RK,GK of
CRT socket normal?
Are the waveform at the
pin21, pin24, pin26 of
IC601?
Are the input waveform
at P601 pin1, pin3, piin5
normal?
The CRT is defective.
The raster don't appear.
Check the signal cable or
computer
IC601 its buffer or its drive
circuit.(clamping pulse,blanking
pulse, is defective)
Video output circuit defective
IC603 pin1, pin2, pin3
CRT drive circuit is defective
heater, power supply circuit
D206, G1, G2, FBT
and its drive circuit.
Turn up the screen
and check whether the
appear.
0.7Vp-p
Heater:
G1: -38V
G2: 660V
Yes
Yes
No
No
No
No
Yes
Yes
No
Yes
3Vp-p
72Vp-p
46
ViewSonic
Corporation
Co
nfidential
-
Do
Not
Copy
G90f/B-3
Summary of Contents for G90f/B-3
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Page 103: ...10 Schematic Diagrams 100 ViewSonic Corporation Confidential Do Not Copy G90f B 3...
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