HP 98770 CE Handbook page 15

Inoperative Unit
(Remove top cover)
I
CAUTION
I
98770 Troubleshooting
4-3
BEFORE REMOVING OR INSTALLING ANY tl,SSEMBL Y DIS-
CONNECT UNIT FROM POWER SOURCE BY REMOVING POW-
ER CORD FROM BACK OF UNIT.
Note
As viewed from rear of unit the left-hand fan is ac powered, the
right-hand fan is de powered.
Turn Unit ON
If no display, then observe Power Supply Indicators. See page 4-2.
Observe the fans. If the ac fan (left-hand) is not turning, check:
a. Fuse
b. Power source (wall connector, power cord, etc.)
c. Computer (use the turn-on fixture)
d. Primary wiring
Note
If the ac fan starts turning as soon as the power cord is connected.
the power-on relay controlling it may be stuck closed.
If the ac fan is turning but the dc fan (right-hand) is not, check:
1. Number 4 LED in the right indicator group.
If lit (brite), power supply is functional. Skip
to Step 2.
2. If off (dark), Power supply is not powered or inoperative. Replace power supply and AS
assembly and do this section again. (see AS and power supply procedure See Page 4-S. )
Check Which LED's Are Lit
The following list is for
Left
indicator group of LED's unless otherwise stated.
LED #1 Lit
- SO Volt supply overcurrent.
1. Unplug power cord.
2. Disconnect high voltage assembly.
3. Plug in and turn on (no display will be visible).
a. All LED's dark, unplug power cord and replace H.V. assembly.
b. LED #1 still ON, unplug and remove A6 board.
4. Plug in and turn on.
a. All LED's dark, unplug power cord and replace A6 board.
b. If LED #1 still lit. go to minimum configuration tests See Page 4-S.
LED #2 Lit
- SO Volt supply overvoltage.
1. Unplug power cord
2. Replace AS and Power supply.
(See AS and Power Supply procedure See Page 4-S.)
3. Plug in and turn ON. (no display will be visible). If LED #2 still lit, go to minimum
configuration tests See Page 4-S.