WOw.... I just can't keep up with the amount of traffic here,it's insane.. I don't even have time to reply to people... messages quickly get lost behind 10 pages of other stuff. I Guess either reply in within 10 minutes, or give up replying altogether... which would be rude..
So forgive me if I can't quote everyone who gave in put on my Nixie Metrix knob problem (refrain please!)....
- 3D printing nooo... it never looks good enough to be credible, and too much modeling work, and I don't have 3D printer. Considering one more and more though, but not for cosmetic parts, only small parts whose mechanical role is the only criteria. ie parts you don't get to see. For example stripped gears in the 20 old broken CD players I acquired recently. Many of them are toast due to a gear with worn out teeth.
- Knob snob.. I don't know about that... don't think it's snobbery, but I jyust cannot stand a non original knob or any part on a front panel. I will always prefer a damaged, incomplete or plain missing knob, rather than some other random knob or pale 3D copy of it.
In the case at hand that missing knob is used to set the sensitivity of the input. It's a small pot that's very light to operate, can do it by grabbing the bare shaft no problem.
- Identifying the original manufacturer of the knobs ? Sure, would be interesting but.... how helpful would that be ? I mean the manufacturer is probably out of business 50 years later, and if not, I doubt they would still make 50 years old knob models ?!....
- Only solution I see is to buy another piece of gear from Metrix, any pieve of junk, sometihng I don't even wnat or need... so long as it is the same vintage as my counter, so that it features the same model ofknobs. Sadly Metrix stuff of that vintage is not pop up very often, and when they do, they do'nt have the tiniest size knob that I need. Plus, sellers wnat 100 Euros or more for their crusty untested piece of junk. 100 Euros shipping for a knob, is a bit dear for my modest budget...
So instead I noticed that some old low end scopes from HAMEG, featured the same model of knobs as my Metrix counter ! Namely, their 207 model, like this one for sale right now, at 50 Euros:
https://www.leboncoin.fr/equipements_industriels/1936744545.htmIt does have tiny buttons, same size that I need for Metrix counter BUT... life is never easy : the Hamed knob is made, internally, for shaft that's a tad bigger, and shorter as well. So the Hameg knob would fit on my Metrix :-(
So back then, I gave up and was lucky to be able to find a foul to buy this piece of junk of a scope, from me. So all in all I didn't loose too much money in the process.
3 years later, in retrospect... looks likes like this Hameg knob was my best option though ! So I feel I will buy another of of these scopes at some point.. hopefully will find one cheaper than 50 Euros. Then do it all again, but this time I will take the time and effort to make that knob fit. The knob not being deep enough, I guess I can just trim the shaft on my counter, just a tad. Won't hurt...
As for the knob having a larger diameter, maybe I can dip the shaft of the pot into some epoxy or something, then sand it down to size, until it fits the Hameg knob.
I really don't know, but I want to fix this problem !!!
Also have my '70s Philips Sig Gen that lost a cap on one of its knobs, during the house move !
I am devastated... Here too, will have to buy a whole piece of gear at great expense just so I can salvage the knobs.
Tube Testers / Curve Tracers.... thanks for the couple links. I do plan on a curve tracer to help me restore my ever growing collection of old Tek scopes.
As Med / Tek said, the best tester is the scope itself, but still, once I find a bad tube, I would to be able to characterize it accurately, just for my own education, to see how it diverges from a new tube. And well, if nothing else, I just find it cool to display a set of I/V curves on the screen, sue me !
A curve tracer is out of my budget. The Tek 576 everyone wnats it seems, it getting more and more expensive every year. There is one for sale here in Frog land... TWO THOUSANDS EUROS !!!!!
That would be 2500 dollars or something, I guess.
https://www.leboncoin.fr/equipements_industriels/1938523815.htm?ac=206978287For that price, as you can see, you don't get to see it power up and in action... I guess that would require 5 grand ?......
Plus, I don't even LIKE the 576 ! I find it ugly :-/ I am not into '70's Tek industrial design at all
I do like my rack mount 5111A but that's about it...
I much prefer the old tube based 575 curve tracer, but even that one is becoming rare and over priced... I see one in Japen for 1,200 Euros, and one in the US for 500 euros / 600 dollars !
https://www.ebay.fr/itm/Tektronics-Type-575-Transistor-Curve-Tracer-S4243/312721154042?hash=item48cfa21ffa:g:JNIAAOSw271dRFaGSo I have given up even on the 575.
So in order to keep the budget under control, yet still use some cool looking classic piece of Tek gear.... my idea is to use my Tek type 502 (or my 502A, but I prefer the look of my 502), since it's an XY scope. I could use it to display the curves. I could also use it to tap all the required voltages to test the tubes with real world voltages. I would get exactly the plate voltages used in Tek scopes. It would also save me from building a HV power supply.
Of course I could also tap the heater voltage to drive the filaments. That low voltage could also conveniently be used to derive 5V DC for digital stuff, like a micro-controller.
So the idea is to design a curve tracer around the 502. I guess it could be made fairly compact since the HV and LV supply and display, are provided by the 502. So I would need to implement the Micro to drive the thing, and some analog circuitry to be able to vary the plate voltage, and measure plate current.
That " uTracer " tester linked a few pages ago, seems to do basically that, so I could study the schematics if available, to reduce development time of my own tester. uTracer displays on a computer though... not proficient with PC programming, and prefer to display on the 502 anyway.
My idea is more a standalone tester, with an LCD display, and a retro look design so as to blend with the 502 scope. So might do a custom folded sheet design, painted Tek blue, and using Tek knobs from some of my donor tube Teks, I don't know...
Also, tester could be made compact for another reason : the very limited number of different tube sockets found in Tek scopes ....like.... 2 ? 3 maybe ? Apart from the big rectifier tube in the power supply, looks to me like all the other tubes use the same socket ?!
Anyway, it would also of course be a nice little design exercise, as I miss designing stuff ! So far since reviving the hobby 5 years ago, I have spent all my time building the lab and fixing broken test gear, then fixing other people's stuff ! . At some point I would like to start designing stuff again...
I would also like to use that tester to characterize Zener diodes or other discrete semi-conductors.
For example I remember the SMPS of a Tek 2215 scope I fixed. Would not power up. Traced it down to a bad 6.8V Zener diode that regulated the supply for the PWM chip that drives the preregulator. It was not shorted or open circuit. Rather, it would "regulate" at a much lower voltage, and regulate very poorly at that, ie had a very high dynamic impedance. Would have loved to be able to disaply it I/V curve on a tester !
Anyway, just yet another little design project on my list.
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Topic: Test Equipment Anonymous (TEA) group therapy thread (Read 18852196 times)