HP 9915A (industrial version of HP 85A)

From: Eric Smith <eric_at_brouhaha.com>
Date: Sun Oct 13 22:20:01 2002

> I am supposed to have an 9915B (that's what it says on the box), but the
> main PCB says 9915-66512 Rev A. Go figure.

The fact that the PCB part number in an HP product has a particular rev
level almost never has anything to do with the suffix of the model number
(e.g., 9915A or 9915B). For instance, the HP-95C and HP-95LX, which
aren't even *similar* products, have 00095-xxxxx parts, with various
PCB revs, as does the HP-9807A Integral PC. (Maybe the Integral was
originally going to be designated an HP-95 with some other letter
suffix?)

It's probable that the 9915A and 9915B have different PCB part numbers,
though both would likely be of the form 09995-6xxxx. This is an HP 5x5
part number; the first five digits are usually (but not always) the base
of the model number. PCBs are usually a -60xxx or -66xxx suffix; repair
exchange boards are usually ordered with a -69xxx suffix, though the board
etch will show the original part number. Subassemblies usually have
-8xxxx numbers, and documentation -9xxxx.

Sometimes on a 5x5 the leading zero is not shown, but it's really part
of the full part number.

4x4 part numbers are for "generic" parts, that are not specific to a
product. Things like resistors, common ICs, and such. Some 4x4 numbers
may only be used in a single product, though.

In the 60s, and maybe in the early 70s, HP had 4x4 and 4x5 part numbers
for model-specific stuff, but they all got changed into 5x5 part numbers
by prepending leading zeros.
Received on Sun Oct 13 2002 - 22:20:01 BST