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Instrument Changes Model 8904A
7-9.
MODIFICATION FOR POTENTIAL POWER SUPPLY SHORT
(Serial Prefix 2817A and below)
A
problem has been noted in HP 8904A Multifunction Synthesizers with Option
002
(a
second output)
and with serial prefix 2817A and below. In these instruments
it
is
possible for the heatsinks on the
output transistors on the A10 Output Assembly (installed only in Option
002)
to touch the bottom
cover when the instrument
is
jarred.
If
the instrument
is
jarred often enough, the anodization (an
insulator) on the heatsinks will wear through and could make electrical contact with the cover. Should
this occur while the instrument
is
on, a
16
V
power supply may short to ground. This may cause the
power supply fuse to blow
or
it
may intermittently cause the following error to be displayed
!!
Reference
Loop
Reports
Out
Of
Lock
!!
To
prevent
or
solve this problem,
it
is
recommended that an insulator
(HP
part 08904-00015)
be
installed on the inside of the bottom cover. The insulator has a peal-off adhesive backing. Place
it
just
behind the front perforations.
It
should cover any scuff marks left by the heatsinks.
7-10.
CABINET PARTS COLOR CHANGE
(Serial Prefix 2914A and above)
NOTE
Serial prefix 2914A changes the color
of
the instrument covers and accessories.
The old color cover and accessories are no longer available.
If
your
instrument
has
serial prefixes 2913A and below, and
you
must replace
one
of
these parts,
we recommend that
you
order the
full
set
of
covers and accessories. Affected
cabinet parts are items
61-67,
and items
69-70
(see table
6-3).
7-14
Firmware Updates/Hardware Modifications
rev.
15DEC89