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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 optput circuit defective
IC603 pin1, pin2, pin3
CRT drive circuit is defective
heater, power supply circuit
D206, G1, G2, FBT, D4410,
Q4410, Q4407, Q4408 and its
drive circuit
Turn up the screen control
and check whether the raster
appear.
0.7Vp-p
Heater: 6.3VDC
G1: -38V
G2: 660V
Yes
Yes
No
No
No
No
Yes
Yes
No
Yes
3Vp-p
72Vp-p
47
ViewSonic
Corporation
Co
nfidential
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Do
Not
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A91f+-1
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