Dear 5401A MCA afficionados,
my beautiful 5401A has finally decided to quit the job, the 5421A Digital Processor stopped working. It started with a memory glitch / broken trace in the left half of the first (leftmost) sector, now there is only a fixed memory dump visible on the screen when reading the memory. Memory Erase does not work either anymore. I guess there is a problem in the digital section / state machine of the processor since the same symptoms showed with a second 5431A plug-in and the analog box seems to be functional. Any hint would be highly appreciated!

Unfortunately, the original documentation seems to be made of unobtainium. Is there somebody out there who could help with a pdf or even an excess paper version of the SM? No question I would offer a proper compensation for the effort to ship a stack of paper over the pond, of course!
It would be pretty cool if could get the 5401A competing against the (fully functional) 3721A again...
Many thanks in advance!

Chris

Hi,
Can't help apart from check the usual suspects, power supply voltages and electrolytic capacitors.
What are you using the 5401A for? Typical use would be gamma spectroscopy but they are pretty rare beasts. I'm a radiation nut as well as test equipment
Robert G8RPI.

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Wow, I have never seen one of these. I did poke around in my usual sources, but also came up empty other than the 1969 catalog (). These were "price on request" items too...exceptionally expensive and low volume instruments I'm sure.

I do wish you success in solving the problem. Fingers crossed that someone on the list will have the service documentation squirreled away somewhere.

On 2/19/20 6:27 AM, ChrisBeee via Groups.Io wrote:

Dear 5401A MCA afficionados,
my beautiful 5401A has finally decided to quit the job, the 5421A
Digital Processor stopped working. It started with a memory glitch /
broken trace in the left half of the first (leftmost) sector, now there
is only a fixed memory dump visible on the screen when reading the
memory. Memory Erase does not work either anymore. I guess there is a
problem in the digital section / state machine of the processor since
the same symptoms showed with a second 5431A plug-in and the analog box
seems to be functional. Any hint would be highly appreciated!

Unfortunately, the original documentation seems to be made of
unobtainium. Is there somebody out there who could help with a pdf or
even an excess paper version of the SM? No question I would offer a
proper compensation for the effort to ship a stack of paper over the
pond, of course!
It would be pretty cool if could get the 5401A competing against the
(fully functional) 3721A again...
Many thanks in advance!

Wow, the HP MCA! I'm sorry that I cannot offer you any documentation,
but I had to comment on this. I knew it existed but I've never heard of
anyone having one. Beautiful!

And that's quite a wall of NIMs behind it. Your lab looks a bit like
mine. =) Have you done anything with CAMAC too?

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

Hi Eagle-Eye Dave? ;-) ,
did not realize that the NIMs were on the picture too. Actually, they were kind of a by-catch when I bought a crate full of Gov Surplus stuff (including the hp 5401A) from one of the the NV atomic testing sites many years ago when I was living part-time time in SoCal. Problem: there was no NIM bin in this lot. I would have liked to get one of these nice hp 5580A NIM bins, but NIM bins are scarce in general here in Germany and finding a hp bin seemed to be impossible. Last year I started to visit the HAM Radio Friedrichshafen here in Germany. Maybe I will find an 'ordinary' Canberra or Ortec bin there some day...
Chris

Hi Mark,
as what per the functional specification can be assumed, the hp 5480A averages repetitive signals in the amplitude domain only, whereas the 5421A portion of the 5401A is capable of doing much more than that (MCS, PHA, Correlation between two signals etc.). One thing in common is that digital amplitude values are stored in a magnetic core memory. I have no clue if these instruments actually came from the same R&D team (maybe someone else knows), but I assume that nobody at hp wanted to invent the wheel twice. It is not beyond possibility that there are shared components or even assemblies. The hpJ March and April 1968 issues suggest though that both instruments were cranked out by the Nuclear Instrumentation Group.

Do you have the manual in electronic form or as paper hardware? I would be interested in whatever is available.
In return: I have paper versions of the following SMs: 5431A/B, 5416A/B and 5406A (system SM only, just external wiring and troubleshooting diagrams, no schematics) from which I can make (partial) scans if this is needed for another repair project out there. Just let me know!
Chris

On 2/20/20 1:23 PM, ChrisBeee via Groups.Io wrote:

Hi Eagle-Eye Dave? ;-) ,

=)

did not realize that the NIMs were on the picture too. Actually, they
were kind of a by-catch when I bought a crate full of Gov Surplus stuff
(including the /hp /5401A) from one of the the NV atomic testing sites
many years ago when I was living part-time time in SoCal. Problem: there
was no NIM bin in this lot. I would have liked to get one of these nice
/hp/ 5580A NIM bins, but NIM bins are scarce in general here in Germany
and finding a /hp/ bin seemed to be impossible. Last year I started to
visit the HAM Radio Friedrichshafen here in Germany. Maybe I will find
an 'ordinary' Canberra or Ortec bin there some day...

Indeed, I'm sorry to hear they're so hard to find over there.

Shipping would not be cheap, but I could part with a NIM bin for a
small sum. I'm not really trying to sell them, but I do have more of
them than I will ever need, so I'm only looking for a few bucks. The
shipping will be the tough part. I don't have any of the HP bins, but
Ortecs and a few others. Ping me off-list if you'd like to discuss.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

Chris,

You might check out the GammaSpectroscopy group here on Groups IO, there are several members who are in Europe

Bill,
that was a very good hint, many thanks!
With the help of Dave and one of his NIM bins, one of my beauties, a hp 5583A SCA, likely will come back to life soon...
For a good reason, the members of the GammaSpectroscopy Group merely rely on today's technology with a lot of software involved. If you want to check your neighbor's imported garden decoration rocks at the next BBQ, you likely don't want to carry a 5401A along. On the other hand, turning these neat geared dials and see the numbers rolling is absolutely priceless!
Chris

Hello Dave,
just in case my e-mail reply to your kind offer ended in your spam folder: you got mail ;-)
Kind regards
Chris

On 3/2/20 2:46 PM, ChrisBeee via Groups.Io wrote:

just in case my e-mail reply to your kind offer ended in your spam
folder: you got mail ;-)

Yup, I've been nonfunctional due to painkillers following a small oral
surgical procedure. I should have that info for you by tomorrow.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

On 2/23/20 3:53 AM, ChrisBeee via Groups.Io wrote:

With the help of Dave and one of his NIM bins, one of my beauties, a
/hp/ 5583A SCA, likely will come back to life soon...
For a good reason, the members of the GammaSpectroscopy Group merely
rely on today's technology with a lot of software involved. If you want
to check your neighbor's imported garden decoration rocks at the next
BBQ, you likely don't want to carry a 5401A along. On the other hand,
turning these neat geared dials and see the numbers rolling is
absolutely priceless!

It's true that the interests on the GammaSpectroscopy list are mostly
about gamma spectroscopy measurements and materials, and less about the
instrumentation. The common focus on using PC sound cards for data
acquisition really makes me twitch, that's for sure.

I do quite a bit of that sort of stuff here (NOT using PC sound
cards); my interest in that area is more in the instrumentation side of
things than most people on that mailing list.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA