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Model
8904A
Service
5.
Desolder the three leads of the backup battery
(A2B1)
with a solder removal tool and remove
the battery.
6a.
If
the instrument has serial prefix
2942A
and below, put the three insulators (HP
3050-0990)
on
the leads
of
the new battery
(A2B1,
HP
1420-0281)
and solder in the battery. The bottom of the
battery case must not touch the circuit board
or
any solder pads.
6b.
If
the instrument has serial prefix
2948A
and above, solder in the battery
(A2B1,
HP
1420-0338).
7.
Remove the resistor and temporary backup connections on the
A2
assembly.
8.
Re-install the
A2
assembly and all connectors.
9.
Place the instrument in its normal operating position. Re-insert the power cord and switch
LINE
10.
Press
SHIFT PRESET.
The display should
show
the correct instrument serial number suffix
for
11.
Re-install the instrument’s top cover.
to
ON.
a few seconds.
rev.15DEC89
Troubleshooting (Memory Backup Battery)
8-48.3