HP 5890 SERIES II Service Manual page 275

Replace Communications Interface PCB
HAZARDOUS VOLTAGES ARE PRESENT IN
THE INSTRUMENT WHEN THE POWER CORD
IS CONNECTED.
DANGEROUS
DISCONNECTING
BEFORE WORKING ON THE INSTRUMENT.
1. Set the main power line switch to the off position.
2. Disconnect the power cable from its receptacle.
3. Allow time for the oven and heated zones to cool.
4. When the heated zones are cool, turn off all gas
supplies.
5. Remove the electronics carrier top cover by
grasping it at the rear and lifting upwards until
its catch releases, then pulling it towards the
rear of the instrument.
6. Remove the right side panel by removing four screws: two each along its upper and lower
edges.
This procedure requires precautions against ESD (Electro- Static Discharge). Use a
grounded wrist strap (part no. 9300- 0969 - large, or 9300- 0970 - small) connected
to a suitable ground. Failure to heed this caution may result in damage to the
instrument.
Depending upon the type of communications PCB installed, there may be one or
more connecting cables installed which must be disconnected before PCB removal.
7. If a non- buffered INET PCB, buffered INET PCB, or HPIB/RS- 232- C PCB is installed, discon-
nect the INSTRUMENT NETWORK (INET) IN and OUT cables from their connectors on the
communications PCB.
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AVOID A POTENTIALLY
SHOCK HAZARD
THE POWER CORD
ELECTRONICS
CARRIER TOP
COVER
NOTE
SVC 10- 2
BY
RED O VISIBLE
OFF ON
SCREWS
RIGHT SIDE
PANEL
SCREWS