Nixie Multimeter

[linuxdr]

Need some help with this fine old meter, I have searched the net and can not even find a picture other than my own.  It is a Systron Donner 9240.  I have managed to get it mostly working but I would love to calibrate it and confirm i have managed to get it fully functional again.  I will put in a bunch of pictures so you see its awesomeness!  I have the missing pair of display tubes on order.  Not the most popular Nixie NL-905.  From the date codes on the chips I am thinking it was built in the very late 60's

[Vgkid]

For manuals Ebay is your friend. Also look into the earlier Solartron Schlumberger multimeters , as they look similar (I thing SD was a Solartron rebadger).

[linuxdr]

I have been looking at eBay, I have been looking everywhere!  The new NL-905 tubes arrived yesterday and I put them in and much to my surprise the two tube are labeled the same but are different.  One tube has the digit for standard mounting and the other has it for inverted mounting.  The internal structure o the tube is also different all the tube that are inverted have a mica back support while the other has a metal plate for the main structure. The data sheet says it should be inverted.  Take a look at the two attached photos.

I have also discovered an odd issue with the meter if I have a reading that needs to display a 2 in the second digit it displays a zero. However, if I need to display any other digit that uses the BCD 2 its fine.  I am suspect that I may have a bad 74141 IC in that section.  But, that would be an odd symptom of a bad 7414.

[linuxdr]

Well I have all the know issues fixed the + - sign tube was not getting signal from down on of the other boards I traced through the thing and found a defective 15846 DTL logic gate. The issues with the number two came down to a defective 7475.  I had to haul out the trusty and very dusty HP 1631A.  Normally, I would not go through the trouble of hauling out the analyzer but this thing is so old and the boards are so fragile  I did not want to risk doing more damage than good.  All thats left is to find a manual and get the thing calibrated.

[jh15]

I have a systron donner nixie frequency counter. Fun to turn on, as fan sounds like jet preparing for launch.

I was around when 'muffin' fans were new.

I should make sure I upload the original manual to a free place.

[ebastler]

I should make sure I upload the original manual to a free place.

That would be great. My recommendation would be the "Boat Anchor Manual Archive":
http://bama.edebris.com/manuals/systrondonner/

(No direct uploads, but there is contact information for submissions at the bottom of the page.)

[linuxdr]

I to have an SD frequency counter.  You can very easily disassemble the old panaflo fans and lube them up.   But they are loud no matter what, the one in this multi meter was completely dry and sounds much better after a bit of lube.  You can see it in action here