Compaq CPQ-C1786FNSL Service Manual page 25

6-4 No Vertical Scan (Raster is one horizontal line)
Troubleshooting
No Vertical Scan
Check I301 voltage of
pin 1 is 12V, pin 4 is
-11V, pin 2 is 40V?
Yes
Check
pin 5 O/P waveform at
I301 ?
Yes
Check
pin 6, 7 of I301
waveform ?
Still no vertical scan
Check or replace CRT
CPQ-C1786FNSL/T (FS7550/V7550)
Ckeck or replace
No
I301.
Check R312, R307,
No R306, R313, R308,
R315, R316
No Replace I401