Restoration Project #35 - Precision E-200-C

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Early 2022 I found an RF signal generator on ebay that was in need of plenty of TLC; Since it fit into my slightly growing "Precision" collection, next to the VTVM and the tube tester, I couldn't pass up the chance. It is a challenging project to say the least. I am not all that familiar with RF and take the opportunity to learn!
Anyhow: follow along as I uncover one problem after the other... can I fix them all?
I think I saw ‪@MrCarlsonsLab‬ doing a slightly earlier revision than this one a few weeks ago. Not sure if it was a new video or just a suggestion... his circuit was a bit different from my unit though.
0:00 Intro - Presentation
1:20 Disassembly
2:50 Carry Handle / Dent
3:30 Case Sanding / Painting / Dial Sanding / Front Panel Polish
4:43 Line Filter Recapping
5:29 Tuning Capacitor: Cleaning / Lubricating
7:38 Axle Rebuild
9:10 Knob Cast / Knob Remake
10:03 Resistor Fail / Potentiometer and Switch Cleaning
11:44 Union Oscillator
12:52 Transformer Rewinding
14:20 Rebuild
14:52 RF Sockets and Output Can
16:12 DC Filter Cap and Power Resistor
18:12 Indicator Plastic Remake
18:38 Turn on / Ouch!
19:38 RF Flatline / Broken Cap / Finalizing
20:45 Two Pending Issues
22:14 Fished (for now!) / Outtake
Music:
My Train's A Comin'
Unicorn Heads
(RU-vid Audio Library)
You can support me on Ko-Fi: ko-fi.com/atkelar
The "tuning knob" OpenSCAD script can be found here: github.com/Atkelar/OpenSCADGa...
I also created a journal post about some of the issues I had that were either too detailed or better suited for a text explanation over here ➡️ atkelar.livejournal.com/85973...

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Опубликовано:

22 июл 2024

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Комментарии : 29

@NoxiousPluK 2 года назад

You seem to have the rare combination of electrical, mechanical and magical skills to pull off amazing projects like this. Love it!

@anthonytiso6365 6 месяцев назад

Very nice workmanship! Thank you for the video!

@t1d100 7 месяцев назад

You might investigate a "DIY Soda Blaster." Uses baking soda for gentle cleaning = Empty plastic bottle for soda tank, Venturi down tube, T-connector, air gun and air compressor.

@agranero6 2 года назад

A suggestion I saw on TV on the show Wheeler Dealers where they restore cars. One of the hosts Antony (Ant) Anstead said that when he was younger he went to near auto mechanics and paid to use some tools (I think it was a painting room). Maybe you can do that to use a sandblaster (common on auto mechanics) without the need to buy one. That things needs space. The smaller I saw is the size of a refrigerator. Incredible when you opened it and it was pristine inside (except for the wiring), and the capacitor reduction is something I never heard of, a kind of friction gear. I love those air dielectric variable capacitors. The design of this things is gorgeous, so compact, the tube in the center of the jig, the coils grounded when not in use. Very cool to watch, a thing that deserves to be preserved.

@atkelar 2 года назад

I did get myself one of these table-top cabinets ages ago; although the real problem is twofld: for one, as far as I am aware you're not supposed to use regular sand (for some health reason?) and I have no clue where I can get the real stuff in an affordable quantity. Also: the gun is practically an open air hose, so my poor little compressor is running without stop when I use it. So I only ever tried it out once before. The frequency is extremely accurate, when it works. It is really a bummer that both the lower half of the "G" band is still stuttering and that the transformer is almost glowing. But I'll keep trying to finalize it and will certainly post a quick update video whenever that will be. I also love the device and would hate to see it go to waste!

@codiecrieg2480 2 года назад

More people should seen your channel. I like your voice ;)

@atkelar 2 года назад

Awww... thanks 😊

@older-wiser-better 2 года назад

Cool as always

@atkelar 2 года назад

Thanks! Glad you enjoyed it, despite not quite being finished. 😊

@PapasDino 5 месяцев назад

Another great restoration...one of the outside variable capacitor plates appeared to be bent outward. Sometimes that gets done at the manufacturer as a final tweak. Just an observation.

@atkelar 5 месяцев назад

Oh, yes: one of the fins was "tuned" indeed. The way I heard about that is to improve the linearity of the capacitor. I did get it to track almost perfectly with the dial, so I think that's working; still need to find out why the highest range isn't quite working though.

@KeritechElectronics 2 года назад

You also use a slide rule? Nice :) Meowsome restoration. I'm all for restuffing old can caps rather than adding new ones under the chassis like Paul Carlson does; makes the device look more original. Speaking of originality... I prefer functionality. None of that "keep the original connectors intact" rubbish. Got a MZN-8C nonlinear distortion meter on my bench where I replaced the super obscure C50 connectors (they look like overgrown BNCs) with SO239s, at least I can get a PL259 to BNC socket adapter (and I've got three of them in my lab) and use the thing... of course after I give it some love because the old thing really needs it.

@atkelar 2 года назад

I need to use the slide rule more often... it's mostly "look up how it works again" TBH; (edit: added after accidental post) If I couldn't find the plugs to match the sockets for some adapters, I would have replaced them with BNC or similar connectors, much like I do with the banana sockets. The strange 2mm style connectors that come with these are not much use to me, and the ones I found look almost exactly like the originals.

@gerardzi7930 2 года назад

This IS a restauration from scratch !

@atkelar 2 года назад

Well, not quite from scratch, but there was a lot to fix in this one indeed.

@3dsmaxrocks699 Год назад

Incredible job. Seems like all electronic repair guys have a cat.......like me. I'm assuming you have a cat LOL That comb thing was crazy!

@atkelar Год назад

I love cats (obviously) but I don't really have enough time to take care of one. I do enjoy the company of occasional neighbor cats. So I'm cat owner by proxy maybe? 😸

@Tibetan1962 4 месяца назад

Love the project -- do NOT love the puppet.

@Ronei70 2 года назад

Excellent restoration! Congratulations! I bought a generator of the same model!! I have a question if you can help me! What is the max output voltage in vpp so I can compare the RF output of mine which fluctuates at 100 mvpp and 360 mvpp (millivolts peak to peak). Big hug from Brazil!

@atkelar 2 года назад

Thanks! I still have that misbehaving upper ranges, sadly, so my values might be a tad bit off. But unsurprisingly, the output varies a bit with frequency, higher ones getting lower pp values. The range is from about 700mV to 300mV pretty much linearly over the (working) spectrum. I poked the "high" output witha x10 scope probe with both attenuators on maximum.

@Ronei70 2 года назад

@@atkelar thanks!!

@djtransnazgrz Год назад

The transformer likely overheats from a shorted turn. At 13:45 you show a sheild that completes a turn and its ends are electrically connected. I bet this is your issue, just insulate the sheild ends and it should be fine.

@atkelar Год назад

Interesting theory; I see your point, but the shield was connected in the original too: there was nothing between the two ends that would have kept them apart. Which is why I didn't bother to put anything in there.

@djtransnazgrz Год назад

@@atkelarMaybe that's what burned out the first transformer as well. Everytime I came across shielding foil in transformers it was not shorted, some had even a gap, not wrapping the windings fully.The only intentional shorted turns I've seen are flux bands in switching supplies, but those are outside of the core.

@atkelar Год назад

Could be; It is the only one so far I've seen with a foil layer inside too. The other cases I saw with a shield had a single layer of a regular winidng that was grounded on one end. I'll check when I get around this one the next time!