Before I put time in making a documentation package (will take me couple of
days) I would check if it is interesting for somebody -- don't want to waste
my time on something nobody needs.
It is Keithley 2001 upgrade. Older instruments had a single PLCC-44
HN27C4096 EPROM for their firmware. That firmware ended at A08 version. Then
Keithley made a newer instrument with firmware in 2 8-bit EPROMs and
released Bxx version firmware with greatly extended functionality. The
latest (and almost certainly the last) version is B17. Bxx series firmware
is too big to fit in that HN27C4096 and that was the reason they made a
newer 2001 version. Those newer instruments have everything identical to the
older ones except a new Digital (CPU) board. That board, in turn, is almost
identical to the older one except having 2 4096 Kbit 8-bit EPROMs (for 8
Mbit total) with some circuitry to interface them to the same CPU instead of
one 16-bit 4096 Kbit EPROM in the older instruments.
I made a small 2-board stack adapter for a single 16-bit 8192 Kbit 5V FLASH,
MX29F800CBTI, that replaces that single 4 Mbit EPROM. It is installed into
existing footprint of that PLCC-44 socket (which needs to be removed,
desoldered). MX29F800CBTI is 2x the older EPROM size, exactly as that 2-chip
solution on the newer boards so it fits the B17 firmware just fine. As it is
16-bit FLASH no additional circuitry is required, just ODD/EVEN parts of
firmware have to be assembled into a single image.
I actually made it 2 years ago but didn't have time to install it until
yesterday. B17 firmware runs just fine, everything fits mechanically without
problems. I built one panel of 9 tops with thin TSOP48 sockets for that new
FLASH 2 years ago, now one of those tops (as it's been said it is a STACK of
top and bottom boards) along with the bottom is in my 2001.
The MC29F800CBTI is readily available from DigiKey and it is not expensive
($5 or so for single quantity). I do still have 8 assembled tops left that I
don't need along with matching bottoms. Also have 9 FLASH chips that I can
program with B17 firmware if there is interest.
I actually have even more of those boards (4 more panels of 9 each) but
those are bare boards, not assembled, if somebody needs them. However, those
should have FLASH chips soldered to those tops directly, without sockets.
The reason is those sockets are rare as hens' teeth and I don't have more of
them except those remaining 8 that are already assembled. As a matter of
fact I DO still have sockets but it is not the SOCKETS that are rare, it is
their COVERS that lock the chip in the socket are. I don't know why but they
decided to supply socket bases and their covers SEPARATELY, as separate
parts and those covers are unobtanium now.
I don't think it is a big problem to have the FLASH soldered in as there
will be no more new firmware available but anyway...
It is relatively easy to upgrade an older 2001 if one have proper
desoldering equipment to remove the existing PLC-44 socket without damaging
the board. However, there is one difficult step is one doesn't have
precision soldering iron and microscope to work with. It is that yellow wire
clearly seen on the attached photo. It is A19 signal from the CPU required
for addressing the bigger FLASH. This signal is not routed to anything on
the older boards, CPU pin is just soldered to an unconnected pad. Not
actually something impossible, something like 10 minutes job from start to
finish at most for somebody who is used to such kind of jobs but might be
impossible without proper equipment and steady hand.
B17 firmware runs OK on a modified older instrument (mine has rev.H digital
board and 0548310 serial number), everything works, re-calibrated like a
charm without any problems today using my Wavetek/Datron 4808 and Keysight
3522B FG for the last step in Low-Level Calibration (2Vrms @ 1Hz -- 4808
can't go that low in frequency). The only quirk was it requires +2.0ADC in
step 14 and 4808 without external amplifier can't source 2A. However, it can
source 1.9999999ADC that should be close enough :)
I will upload all design files and some pictures from the upgrade process if
there is interest. No reason to bother if nobody is interested.
Will also sell those boards including those remaining assembled tops with IC
sockets and FLASH chips pre-programmed with B17 firmware.
BTW, it tells it is 2001M, not just 2001 with that B17 firmware :)
P.S. Sorry for attaching the photo instead of putting it into files -- don't
want to waste the file space if nobody is interested.
---
*
* KSI@home KOI8 Net < > The impossible we do immediately. *
* Las Vegas NV, USA < > Miracles require 24-hour notice. *
*
Sergey Kubushyn
