Monroe Calculator as Source of Nixies?

[Daniel McDonald]

I have a Monroe 620 Calculator that I bought a long time ago, intending at the time to use its Nixie tubes for some other project, and I am now questioning the wisdom of that train of thought.

It's got 13 tubes in it, I think all of them work.  According to Rick Bensene, they are "JPC B-5755's (clones of Burroughs parts of the same part number)".  But now it has some sentimental value to me as a unit which might outweigh the value to me of the individual tubes. 

Is there any collected wisdom about the scrapping out of non-prime systems for their tubes?  I've got a moderately-sized stash of ZM1000's out of things with no sentimental value that will keep me going for a little while, but those 13 additional tubes still have some possibilities.


For reference, here is a link to Rick Bensene's Monroe 620 info:

http://oldcalculatormuseum.com/monroe620.html

What is good/sentimental about my particular unit?

 - I bought it from Ed at The Black Hole on a very memorable visit, and that experience (sadly) can never be repeated.
 - It has the way-cool-provenance property sticker of "LASL-AEC" on it

What is not so good about this unit?
  - It doesn't work reliably.  This could probably be fixed.
  - It's missing the decimal place knob.
  - Some of the top vent holes have been bashed and a few of the plastic strips are broken.
  - Ed wrote "$5" on the top of it with black magic marker

Thanks for any advice or wisdom,

Dan M.

[David Forbes]

On 4/11/11 10:33 AM, Daniel McDonald wrote:
> I have a Monroe 620 Calculator that I bought a long time ago, intending
> at the time to use its Nixie tubes for some other project, and I am now
> questioning the wisdom of that train of thought.
>
> It's got 13 tubes in it, I think all of them work. According to Rick
> Bensene, they are "JPC B-5755's (clones of Burroughs parts of the same
> part number)". But now it has some sentimental value to me as a unit
> which might outweigh the value to me of the individual tubes.
>

Those tubes are similar to the B5866, which I have a few hundred of.

Keep the calculator intact!

--
David Forbes, Tucson AZ

[David Forbes]

On 4/11/11 10:37 AM, David Forbes wrote:

> Those tubes are similar to the B5866, which I have a few hundred of.
>

Oops, I meant to say that I have lots of 5853s, which are the
high-pressure tubes used in calculators.

The 5866 +/- tube is indeed hard to find, but they're usually trashed by
the time they've been in a calculator for 30 years, so they're not worth
scrapping a calculator for.

[Nigel]

Definately keep the calculator intact. It should be possible to restore it to it's former glory.

 

$5? Wow!

 

Nigel.

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[Terry S]

It's a dilemma.

Some years ago I found two calculators with pandicon tubes at garage
or estate sales, within a few weeks of each other. Both were in
perfect shape, both working. One was branded "Logic Data", can't
recall the other, but electrically it was a clone of the first.

I have no interest in collecting calculators, but I recognized the
historical value of these items. I basically gave one to the guy who
runs the on-line vintage calculator museum, and sold the second one on
eBay -- for not much money.

I wish now I had scrapped both for the pandicons. I'd love to make a
pandicon clock.... And did anyone see what that last pandicon sold for
on ebay?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.l2557&rt=nc&nma=true&item=190511988634

So while keeping the calculator intact has it's own merits, there are
certainly cases where it makes both economic good sense and good old
common sense to scrap a device for the tubes. Nice clock or clunky
calculator? Valuable tube or low value device?

Terry

[Andy Tefft]

I had a similar situation. I was able to rescue a bunch of nixie frequency counters in various stages of functioning. I decided I didn't want to trash working equipment so I designed a clock that would use a counter almost as-is (I only had to add one wire so I could trigger a reset). I never took it past the prototype stage but I really liked the whole idea.

In a calculator you could kind of do the same thing -- maybe just interface with the number (and clear) button switches so that you can "enter" any number you wish on the display!