HP 98780 CE Handbook page 12

4-2 98780 Troubleshooting
Problem Charts
The following charts attempt to list some of the more common problems and identify the most
probable assemblies associated with that problem. The numbers in the charts indicate the
probability; i.e., a "I" is the most probable cause and a "4" is the least probable cause.
Raster Problem Chart
No display
Improper focus
Improper intensity
No high voltage
Symptom
No raster deflection
Distorted raster shapes
Alpha Problem Chart
Symptom
No alpha display
Improper or incorrect characters
Characters missing (every other line) or incorrect
Incorrect highlighting
Alpha cursors missing or incorrect
No alpha blanking
Graphics Problem Chart
Symptom
No graphics display
Extra or missing vectors
Extra or missing arcs
Improper or no area fill
Improper line type or no line type control
Random or repetitive dC)ts either !Tl!ss!ng or
always on display
Intermittent display dots
Can't read or write into graphics memory
Graphics cursors missing or incorrect
Probable Cause
A12/ CRT/ HV
All
A14 Yoke XFMR
2
4
A21
2
2
2
4
2
2 3
3
3
2
Probable Cause
A3liA32
3
3
A34
2
2
Probable Cause
A3liA32
2
2
2
2
2
2
A5liA52
2
1
2
3
3
4
2
All
4
Heat
sink
1
2
3