OK so I promised some good stuff, here it is.
Remember that old Nixie counter I got recently, made by " Rochar " a defunct French TE manufacturer ?
Well I really love it, so I got more from them ! A couple bench Nixie DMM !
Got the first one in january IIRC. A friend pointed it to me on leboncoin.fr.
Looked cool but seller wanted 100 euros for it, go away you speculator capitalist !
He was advertising it not as a DMM, but merely as "a source of Nixie tubes" !
I put it in my "like" list" anyway, in case the prices might drop to a more reasonable level one day.
Well believe it or not, the very next day, he relisted the tihng for 50 instead of 100 !!!
50 Euros that's my usual max budget for impulse buys of old / collection stuff, so I immediately pulled the trigger !
Bonus point : guy had the original power cable ! Extremely valuable because the DMM uses, just like the counter did, a now long obsolete power plug !
When I received the DMM, the cable was missing !
I thought OK give up Vince, you got screwed, no point arguing with the guy it's a waste of time.
But, since the cable was really unobtanium and it takes not much time and money to send the guy a message... I played dumb and asked about the cable.... to my great surprise, showck and amzament, the guy was actually honest ! He apologized and immediately sent it to me at his expense !
That's NOT how things usually go over here, not at all !
Then I started actively searching leboncoin.fr for "Rochar".. and guess what, Murphy loved me and just a few weeks later I found another one !!
Same model, different version, cool !
Guy wanted 90 for it, better than 100 but still too much. I offered him 70, he accepted, not even a counter offer, and even better, after exchanging a few e-mail about this and that, out of the blue he said he would do it for 60 not 70, me asked for nothing I swear !
So... X-mas really.
So have two lovely Rochar Nixie DMM now.
Model A.1135
Manual is available on-line, with all the goodness you could want from a good manual
There are 4 different variants of this meter ('no suffix', and suffix B/C/D), depending on the combination of 2 variables :
- Whether it's DC only, or AC + DC. If the latter it also enjoys auto-ranging as well.
- Whether it has printer port at the back.
I have a ' B' and a 'D'.
'D' : DC only, manual range, but has the printer port./
'B' : AC/DC, auto-range, but no printer port. However it looks simple enough to retro fit that : it's just a DB25 connector, and the rear panel is precut, and the PCB has already the mounting holes for the connector. The wiring then is dead simple, as you can see on the pics below.
Specs : good enough that I can actually contemplate using the thing, not just looking at it ! It's a lab grade instrument not a toy. It's actually much more accurate than my goto/dailty driver Fluke 11 meter !
0.2% + one count, vs 0.9% for the fluke IIRC.
Count-wise, I love it, it has an interesting feature ! It's a 5,000 count meter, but 2,500 count resolution. Did I just lose you there ? Explanation : the display does count only 2 by 2 ! It display only values in 23 steps, only even values. This way get a wider dynamic range for your 2,500 count. So it will only display say 0mV, 2mV, 4mV... but never 1 or 3 or 5 or 7 or 9mV.
Weird eh ? Has anybody seen this on another piece of TE somewhere ?!
Impedance : HIGH. 5Meg on all ranges AND a super high 1,000Meg impedance on the 5V range.
Ranges : 5/50/500V.
So... yeah, it would be ideal to test the power rails on mly old glowing Tek TE ! How cool that would look to troubleshoot a Tek scope with a nice Nixie DMM of the same era ?!
Looking forward to doing that and taking some pics !
So, even though I have had these two bad boys for some time now, believe it or not I have NEVER even tested them so far ! This evening is the first time I look at them.
Piccies now eh. First a few family pictures with the two DMM and the counter. MY 3 Rochar pieces gathered. Then the two meters side by side.
The I took apart one of them, the suffix 'D', because it looked like it was in worse shape than the other and I wanted to see inside...also because the seller used foam chips to pack it, and the foam bits found their way in abundance inside the meter ! So wanted to open it up if just to get rid of all that foam !
So all the close pictures are from this one.
- It's missing the 4 screws at the bottom, that secure the chassis inside, to the cabinet. so the chassis is wandering in there, not good !
- It's missing also its 4 rubber feet, because said screws were also securing the feet. Luckily looking at the other DMM, these feet look like standard rubber feet. I should have no trouble finding a good replacement.
- Some surface rust outside on the back panel. Rusty screws as well. So will need new screws, and sanding/priming/painting of the panel. Inside of the panel is rusty too as you can see.
- Surface rust also inside the cabinet, on the bottom.
- Surface dust also, well pitting at least, on the chassis. That less fortunate... would need to buy brushed to get rid of the pitting in the nooks and crannies. Then apply a coat of clear rust remover/sealer or something...
- Printer port / DB25 is pitted too, and its mounting screws as well.
- More rust on the mounting bracket, painted black, that holds the Nixie tubes. Again not difficult to sand down and prime/paint.
- Front panel : looks.. well not so good, but a good clean and it should come out just fine I think. It's well used but I think maybe I could improve the knobs with a polishing/buffing wheel... which I would have to buy first !
Then redo the white dot on the big red know. The polish the bright work. I thing it could look very nice with some TLC !
- Display colour filter : same design as the counter, so same problem (on both meters) --> the orange colour filter half dropped inside the cabinet, because the foam that held it in place has long turned to dust...
- Components : on the underside, see close up, there are a couple yellow axial components, that are leaky. Not even sure at this point if they are caps or.. maybe batteries/cells (for the voltage reference maybe... will need to look that up in the schematics).
The internal construction and topology is very similar to that of the counter because.. well, same era, and deep down it IS a counter... DMM does a voltage to time conversion then it measures the width of the pulse. So again, like in a counter, we have Nixie decade boards that divide a clock signal.
So now that I have it apart, might as well start restoring it right now, and of course fit an IEC power socket to make my life much less miserable, and allow me to actually use all my Rochar TE.
OK pics now.
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