Troubleshooting; Initial Checks - HP 98770 CE Handbook

Check
[s the base operating?
(Try PR[NTER [S 0
PR[NT "HELLO")
[s there any display?
Adjust intensity control.
Press control-stop
[s there a cursor?
Check voltage select switches,
fuse, and line power.
Still no display?
98770 Troubleshooting
4-1
Chapter
4
Troubleshooting
Initial Checks
Action
Yes - Proceed with [nitial Checks.
No - Fix base.
Yes - Proceed to Raster Checks
No - Proceed with [nitial Checks.
Yes - Proceed to Raster Checks.
No - Proceed with [nitial Checks.
Correct any fault.
Proceed to Inoperative Unit Checks.
Inoperative Unit Problem Chart
(Remove top cover.)
Symptom
Fuse keeps blowing.
Neither back panel fan runs.
Fan above voltage selector switches doesn't run.
Probable Cause
Fault in: Power Supply
Rear Panel Assembly
Transformer
Spark Gap
Fault in: Rear Panel Assy
Turn-On Relay
Transformer
Fuse located below power
supply (early units only).
Fault in: Power Supply or other
area of unit. (See Power
Supply Indicators)
Fan
Proceed to Inoperative Unit Problem Chart -
Power Supply Indicators.
I