SP-252 Seeking drawings

[Richard Scales]

I'm looking for any details of the pinout of the Sperry / Beckman SP-252 Multi Segment display which are any better than the one that I found over at tube-tester.com:

https://tube-tester.com/sites/nixie/data/SP-252/sp-252.htm

I'm making a footprint and need to get the pin positions as accurate as possible. My usual process for this is to copy the pin positions into a spreadsheet and make a scattergram which should represent the pin positions. 

This allows me to spot any obvious blunders. It's just that the image I have is not that clear and there is some information missing (IMHO) so if anyone can point me to anything better I would be most grateful.

I could not find it in the Sperry Information Systems catalogue for which I already have a PDF.

- Richard

[Audrey]

You could scan the bottom of one using a scanner and convert to inches/mm using the DPI.

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[Richard Scales]

I used to so that but it relies on all the pins being straight and for this particular display - there are 30+ pins in a very small space - the more accurate the better - especially when it finally comes to plugging the things in!

Perhaps the differences are so subtle it's not worth worrying about. It's like staring at constellations! This group on the left seems a little out of alignment when compared with the image from Sperry, it's counterpart in the image for the character on the right looks more like my chart - yet - from the data I have logged - the chart shows similar groupings for left and right - is their image wrong ? is their data wrong?

When daylight comes I'll get eyes on the physical display though I fear at my age - that may be the least helpful method!

- Richard

[Benoit Tourret]

Hello Richard,

have a look on the SP-351, 

https://www.tube-tester.com/sites/nixie/data/datasheets/SP-351_SP-352-drawing-01.jpg

not the same number of digit, but some of the pins should be identical...

On my SP-356, there is 0 aligned pins on a diagonal way. only in horizontal.

[Richard Scales]

Hello, there are indeed a few the line up - it's the ones that don't that worry me the most!

 - RIchard

[Jon Jackson]

Don't know if this will help:

Sperry SP-352 and SP-332 Gas Discharge Clock Display pinouts from 1973 catalog (attached).

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[Jon Jackson]

Oh, probably not since I misread SP-252 as SP-352. Apologies !!

[Benoit Tourret]

try to find 0.5 mm inner diameter pipe, 10cm long, fit all the pins, pour some silicone, you should have a good representation of the socket... if you didn't forgot to add some wax or similar to unmold the silicon.
the more parallel your pipes will be, the more accurate your print will be.
for a good print, the end of the pins is not important, the most important is the place they have at the beginning, the nearest to the display. without sacrifying a display; I don't see any other way to have a good measurement.

[Richard Scales]

Thank you Benoit but I need actual data to make a footprint to use in PCB design application.

I think I'm mostly there but was really seeking a better picture so I can confirm the accuracy of the supplied numbers and to which pins they apply - some of the ones buried in the centre of the display are not so clearly linked to the numbers at the side.

 - Richard

[Dekatron42]

Have you asked Dieter if he has a better scan that he can share?

/Martin

[Christian Riise Wagner]

Can't help you with better drawings, but I can recommend 3D-printing a small piece with the holes at the planned locations to verify the fit before sending off the board for production. I've used this technique myself a couple of times.

[gregebert]

Make sure the holes for the display pins are larger than minimum; I made my own footprint for the SP-151 and it was difficult to get the pins fully aligned when trying to solder it in. Larger holes makes it much easier to insert the display for soldering.

Also beware of the glasshole, as I call it. It's the fill-tip when the display gets gassed-up, and you need to make the PCB hole large enough to accommodate slight manufacturing variances in diameter and location. I think I used a 5mm hole, and keep traces spaced away as much as possible in case you need to make the hole larger. I didn't have any glasshole  problems on my boards.

[Richard Scales]

Many thanks again,

@Christian - that is a sound plan, will do/

@Gregbert - noted though I never solder these things in, I make sockets for them every time which makes insertion/removal and replacement relatively easy. I purchase 40 way turned pin sockets and break the pin sockets out of them to fit into the right sized hole on the PCB and I always make an oversized hole for the 'glasshole'.

I've already made footprints for many different displays including SP-33x, SP-35x,  SP-101 and  SP-151 - made as sockets.

This is the display board for a different clock that uses SP-332 displays.

 - Richard

[Richard Scales]

After much cross checking between digits I have now settled on what I believe the final measurements are and this is the result:

The left half will sit right on top of the right half so there is x & y consistency between the two characters, the risk of the part fitting is tending away from zero!

- Richard