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Model 8904A
Service
HOW
TO RESTORE THE SERIAL NUMBER
IN
A
REPLACEMENT A2 DIGITAL ASSEMBLY
Description
If the A2 Digital Assembly has been replaced by
a
new
or
exchange assem,,;, the instrument’s serial
number suffix will need to be entered into non-volatile memory (RAM). The suffix is the last five
digits of the serial number.
For
example, the suffix of serial number 1234A56789 is 56789.
The serial suffix can be entered from the front-panel keyboard by the following procedure. Note,
however, that the procedure will only work for an assembly coming from a Hewlett-Packard sales office
or
service center. If the instrument has lost the contents of
its
non-volatile memory (for example, if
the backup battery fails), the serial number cannot be entered; the A2 Digital Assembly must first be
replaced, then the serial number can be entered.
The procedure is written with simple steps followed by detailed notes. Normally, it
is
only necessary to
follow the simple steps and ignore the notes. Refer to the notes when a step doesn’t work quite right.
NOTE
If the instrument
htls
Option
001,
003,
and/or
005,
these options can be
restored after restoring
the
serial number. Refer to the procedure following
this one.
Procedure
1.
Switch
LINE
to
OFF
and then back to
ON.
After the instrument powers up, the display should
read
*I
*
HP
8904A
Main Selection Level
I
fl
Channel Confia.
NOTE
After about
3
minutes
if
no key
has
been pressed, the backlighting on
the display will
go
off.
This
is
normal.
When
another key
is
pressed
the
backlighting will
go
back on.
2.
Press
SHIFT
PRESET.
The display will look something like the following, then after about
3
seconds it will time out. (The example shows an instrument with Option 002 installed.) Check
that the serial suffix is
00000.
HP
8904A
Opts
02
Firmware Revision
18387A
Serial
No
00000
rev.
15DEC89
Troubleshooting (Serial Numbers) 8-43