Products > Test Equipment
Test Equipment Anonymous (TEA) group therapy thread
Cubdriver:
Did some more work on the NLS meter tonight - cleaned the contacts on all of the display unit lamps, and ohmed them out (found two bad ones; replacements have been ordered from the Bay of Evil and should arrive in about a week). It's very cleverly designed - the bezel is lifted a bit and two retaining tabs disengage from the front panel, it may then be pulled straight forward and out. The display pivots on two bosses near its bottom and is retained by a pair of small clips at the top - to remove it the clips are moved outwards slightly to disengage and the whole assembly is pivoted forward then pulled straight out. The lamps stay in the display unit, and there is a PC board with an array of spring contacts underneath it.
Bezel removed; left hand retaining tab being disengaged:
Tabs disengaged, display pivoted slightly forward:
Display just prior to removal:
Bottom of display unit showing lamp bases (as removed - note oxide and general grunginess of contact buttons):
Contact array - front center contact was obviously replaced at some point in the past:
Display base detail after bulb contacts were filed to clean them, showing a lamp removed from its cavity and the ground contact spring extending into the cavity. These springs may yet need to be removed and cleaned. Cavities with black marks next to them are left empty; I marked them to prevent confusion as to where lamps go:
-Pat
Cubdriver:
And a quick video showing that more of the lamps in the display are now working:
(I need to get a camera that can close focus!!)
-Pat
bsdphk:
I doubt that cable is for sub-sea use, almost all such cables have at least one layer of steel, and much thicker envelopes.
But it is not a trivial cable either: It could transfer between two and thirty thousand simultaneous telephone conversations, depending on the route and repeater spacing.
Vince:
--- Quote from: Cubdriver on June 27, 2022, 07:57:09 am ---And a quick video showing that more of the lamps in the display are now working:
(I need to get a camera that can close focus!!)
-Pat
--- End quote ---
As much as I enjoyed the video, I think you should stop making them... for the good of your TE ! :-DD
You are too nervouis when on camera, at the beginning you dropped the display assembly then tools soon after ! :scared:
The health andf well being of your TE comes first, our curiosity second.... which is satisfied anyway with the still pics.
That display unit looks really cool and cleverly designed indeed ! 8)
Thanks to your pics and video I now realize I was wrong about how I thought this antique display technology worked !
From your previous videos, with all the noise the instrument was making when those digits were changing, I thought the display was a mechanical device and the noise were the digits being being moved in an out, like you have on some old alarm clocks...
But no ! So the noise is entirely due to the switches behind the display, but the display itself is 100% static, no moving parts. The 10 digits are all stacked up, immobile, made of an engraved piece of glass or perspex, that's lit from the bottom/edge via all these lamps ! How cool... so the display itself can't wear out and can be operated at high speed, no worries.
So it's very much the same concept as Nixie tubes, all digits stacked in front of one another, common terminal and light the digits you are interested in. Only difference is the source of the light. Incandescent in this meter, and gas discharge in the Nixie.
So this old display is actually more repairable than a Nixie... all that can go wrong is a bulb frying from being turned on and off all the time at high speed, but they are designed to be very easily replaced so no worries, they anticipated that. Whereas the Nixie once it wears out or loses gas or whatever... not much you can do !
Yeah I like your instrument more and more, really cool display, they came up wit a really nice design for something this old ! :-+
May you keep ti running for many years to come. 8)
The one thing I don't quite understand though, is that it looks like there are only 8 bulbs per digit, so not sure how they light up the two remaining ones ?! :-//
Vince:
Morning here, doing my first check of leboncoin.fr ads, and saw that :
https://www.leboncoin.fr/bricolage/2182739080.htm
Apparently posted last night at 21H14min
A cool Tektronix DMM 916, looks well featured, for only 20 Euros.
Guy says it reads current OK but all other modes are defective and the display is stuck reading : " Probes ".
Sounds like something that could be fixed... or at least well worth a shot at only 20 Euros.
Sadly like anything worth anything on this website, it's already sold, I am too late ! |O
Not that I could have bought it anyway, but still...
So really that goes to show there are sometimes decent stuff out there... but you need to run your searches every 5 minutes day and night, never sleep, never work, never eat/cook, never go to the toilets, never go out to buy groceries... no, you need to be 24/7 on the site running your searches/keywords constantly. I can't do that, I am not a robot :--
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