HP 410C Vacuum Tube Voltmeter Restoration

Рет қаралды 46,718

Күн бұрын

Another classic Hewlett-Packard instrument saved from the trash bin: the HP 410C VTVM (Vacuum Tube Voltmeter).
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Пікірлер: 221

@johntomassetti3818 10 ай бұрын

Marc, I am a transformer engineer. I would be happy to reverse engineer the damaged power transformer for you. Let me know.

@PsRohrbaugh 10 ай бұрын

We need to make this happen! Marc please contact him!

@TheCanadaboy25 10 ай бұрын

I would love to see a video on that. Hopefully Marc takes him up on his offer!

@gutschke 10 ай бұрын

I was surprised how inexpensive it can be to buy a custom-wound transformer. A couple of years ago, I needed an unusual combination of voltages in an unusual form factor. On a whim, I reached out to a vendor on EBay who offered a couple of different models that were close but not perfect matches. And it turned out they were a small outfit in China that didn't mind building me a transformer to order. Maybe, I just got lucky, but I didn't pay more than I would have had to pay for any COTS transformer and got exactly what I needed. I realize that there are a ton of parameters that can be tweaked when designing transformers. So, depending on what exactly needs to be done here, things could be more complex than merely enumerating the expected voltages. But it certainly is worthwhile looking into.

@arjovenzia 10 ай бұрын

Transformers are pretty neat widgets. I had a passion project to build a tube amp, output transformers are heavy, vacuum tubes weigh less than air. So I figured roll your own, cos I found a motor rewind shop with a crusty ol Elmer. He knew motors n windings n ratios, I knew enough electronics to be pretty dangerous. Neither of us knew much about valves. But we got it working very well

@twotone3070 9 ай бұрын

I wanted Marc to say that they were going to rewind the Xformer.

@jeremiefaucher-goulet3365 10 ай бұрын

28:06 "There's an adjustment for infinity" This is next level god-like powers being able to set infinity at a specific fixed value. Marc is the Chuck Norris of Ohms.

@av8bvma513 10 ай бұрын

But can he adjust my Nadir?

@acmefixer1 10 ай бұрын

Did you know there are many infinities? That's what the theoretical mathematicians say.

@jeremiefaucher-goulet3365 10 ай бұрын

@@acmefixer1 yes. Some infinities are bigger than others.

@miroslavstevic2036 10 ай бұрын

@@jeremiefaucher-goulet3365 We can not say it like that. Some infinities are different, not bigger then others. Infinity multiplied by finite still equals infinity. So there is only one infinity in that sense. But there are different types of infinities. For example, infinity in complex numbers is not the same as integer infinity. Or, infinite time is not the same as infinite space. What is bigger, infinite time or infinite space?

@CuriousMarc 10 ай бұрын

Thanks I feel better and more powerful already.

@janosnagyj.9540 10 ай бұрын

Rewinding that zapped primary is a lazy weekend's job 😅 It might be another episode for us as well 😉

@mrnmrn1 10 ай бұрын

Not if it is potted with epoxy. The laminated core could be a nightmare to de-laminate. But worth a try. If the same size transformer core is available, might worth cutting the old one apart with a grinder, count the number of turns and build a completely new transformer for it.

@TomKappeln 10 ай бұрын

"This transformer is imposible to find ..." Buys original Apollo and Aircraft parts ...

@TechGorilla1987 10 ай бұрын

Consistently some of the fastest-passing content on the 'Tubes. It could be an hour long and the only thing I would change is to pop some popcorn.

@CuriousMarc 10 ай бұрын

Thanks!

@searchiemusic 10 ай бұрын

i appreciate you utilizing your accent for the spongebob joke

@TB-nz4kf 10 ай бұрын

It was great to see these meters show up on the channel. Them came from the Fisher plant in NY when they shut down in the 70s or 80s. They were then stored in NJ for some time if I recall correctly. The owner then move to FTL where they were store in a loft for more that a few years. His company was being sold around 2016 so the EQ had to go. They gave the EQ to people that would promise not to sell it, but move it along to others as time goes on. When I looked inside of these I could tell I had no hope of making them work again. Then a found this great channel and know if anyone could fix them it was this crew. Thanks for the great channel!

@ragrabau 10 ай бұрын

And another example of why HP was always considered some of the best test equipment money could buy. Thank you Mark for saving another piece of electronic test equipment!

@carpetbomberz 10 ай бұрын

Truly the HP gear takes a licking and in the right hands (schematics, parts and experience), they keep on ticking, scoping and measuring. 👍

@fabiog801 10 ай бұрын

Hi Marc, i just want to tell you this : i am an italian craft brewer who lives in argentina with ZERO knowledge of electronics but still i find your videos 90% understandable and strangely very interesting to me. I followed the channel for years. Today i thought that this fact is totally odd and you deserved to know it. I really admire the thought process you follow. How you solve problems without getting stressed.. oh and you wotk with geniuses. The guy with the white coat who can reverse engineer everything. And the kid that made the rope core memory reader is over the top. Dude i cant fix my fridge.

@CuriousMarc 10 ай бұрын

Wow, and thanks for the kind words! You’re just like me. I have zero knowledge in beer, but I like it very much!

@vincei4252 10 ай бұрын

"If you are dumb enough to short out the fuse ...." Words to live by.

@Evergreen64 10 ай бұрын

I've always been so impressed with the creativity of the engineers at HP. They really worked with what they had to do some amazing things.

@CuriousMarc 10 ай бұрын

They were genius analog circuit designers.

@gvii 10 ай бұрын

That was really interesting. I have a huge soft spot for these old bits of equipment, so it warms the heart to see at least one of the two brought back to life. Thanks for sharing this, it was a lot of fun to watch.

@vmiguel1988 10 ай бұрын

I am disappointed without transformer rewinding!

@simontay4851 10 ай бұрын

There is no way even curious marc could repair such a specialised transformer. The secondary has lots of taps and is on top of the primary. To get to the primary, he would have to unwind the secondary and he doesn't know how many turns the primary has. Its fxkd.

@lyrebirdcyclesmarkkelly9874 10 ай бұрын

Actually not that hard, Tx has only three secondaries, called out on the schematic. I used to design and build specialist drives for turntables and routinely got custom transformers wound to my specs for surprisingly little money (often

@Andy_T79 10 ай бұрын

@@simontay4851We can put men on the moon, ISS 25 years in orbit, space telescopes, satellites, auto landing and reuseable launch vehicles, probes, rovers, and helicopters on Mars, .... but 'No way' could we rewind a 60s transformer! Yes you're right that kind of alien tech is lost to the sands of time along with pyramid construction techniques! 🤦‍♂️🤣🤣

@jasonmurawski5877 10 ай бұрын

@@simontay4851sure he could. It’s 3 outputs on the secondary, probably 3 separate windings, too. The schematics may tell you the number of turns, but if it doesn’t then you can easily calculate it since you know the voltages

@OmarMekkawy 10 ай бұрын

Maybe it's time to learn how to rewind transformers ? 😂

@DrFrank-xj9bc 10 ай бұрын

Marc, thank you very much. Very nice, that you restored this old VTVM.. I've done that @ Airforce lab 1980-1982. I've repaired and calibrated many of those and similar instruments with different optical choppers. hp also used synchronous motors with hole disks, which interrupted the light beam of small incandescent light bulbs. At eevblog, we have replaced those neons in FLUKE 845AR/AB instruments. Those neons need to fire in the dark, so at that time, radioactive substances inside the bulbs were added. One of those neons is the AC3/NE-2U, which fires at

@CuriousMarc 10 ай бұрын

You would be right. Neons in photochoppers need to fire in the dark, so they always have a trace of radio active element added to the gas (that's what the little dot in the neon means in the schematic). We'll replace it with the correct bulb in the next episode.

@jlwilliams 10 ай бұрын

I like to think that this weekend at the Old Engineers' Home there's some old red-faced guy looking extremely embarrassed because his buddy just pulled up the CuriousMarc channel on his tablet and said, "Hey, Delbert, remember that time you smoked two HP VTVMs because you were too lazy to wire up the right probes?"

@SeanBZA 10 ай бұрын

Neons are selected Ne2A, selected for having the same breakdown voltage, and then put into pairs.

@jamesnorman415 10 ай бұрын

This episode reminds me of my student days when I was the student lab assistant. I learned more about electronics while repairing the test equipment that my fellow classmates destroyed than listening to the lectures. 😊

@TheDefpom 10 ай бұрын

I designed a replacement PCB for the 3400A to replace the chopper board, it’s up on PCBway.

@Edisson. 10 ай бұрын

Hi, I saw the video, great work, my 3400A is not working yet - it was damaged a lot and that's probably why it looks like new (probably it was broken for a long time in some warehouse) the input amplifier with Nuvistor was fried. Similar work with the design was done by Mr. Carlson, did a huge amount of research on neon lights and ended up redesigning the entire circuit and replacing the neons with red LEDs. Nice day 🙂 Tom

@ifitsrusteditsmine 10 ай бұрын

Marc, a guy that enjoys both playing with pure junk and Apollo modules.

@simontay4851 10 ай бұрын

The previous man's junk is curious marc's treasure.

@mathewmcgill6266 10 ай бұрын

During my early career in the Air Force, I use to calibrate and repair those meters. The red push button switch should light up when on. HP was the world standard for quality equipment. Damn near all the equipment were either Hewlett Packard or Tektronix. I wanted to cry when it was relegated to a company that manufactured cheap printers.

@CuriousMarc 10 ай бұрын

I’m crying with you!

@kaviter77 10 ай бұрын

I envy you. You live in long lasting democratic country that had all this cool devices. I'm from Poland. Thru communist time we fall so much behind western countries in technology, and of course all this nice western devices were not available here. I got my hands on fancy polish multimeter from 70's, that was aimed only for state professional market back in a day, and most likely costed fortune in communist reality. I managed to restore and fix all electronics using original old parts (except electrolytic caps), I only miss now nixie tubes that someone took from my meter for some stupid clock. Hope to soon find some in reasonable price (build some LED replacement for purpose of renovation) and put it back together. I'm really surprised how good it actually is. Best regards Marc, you are by far my favorite KZbin channel.

@keithmarlow 10 ай бұрын

whoever was trying to restore the units before clearly didn't know what they were doing, or didn't have the right equipment to properly fault find. Golden rule, if you don't have the experience or equipment, leave well alone.

@fritzkinderhoffen2369 10 ай бұрын

VTVMs are special equipment that always could do things that regular VMs couldn't. This is high end and you undoing the damage done to them a joy. Hope you get plenty of use out of the one that you resuscitated. Look forward to the follow-up video!

@I967 10 ай бұрын

Excellent work, Marc, thank you for another HP episode. I'll be looking forward to the second part. Pity about the burnt transformer. I'd look into having it rewound because here in Europe these are rare, which is probably not the case in the U.S.

@ericpaul4575 10 ай бұрын

Come on, I think you could rewind a transformer. After all the other amazing fixes, a transformer rewind should be simple.

@atschirner 10 ай бұрын

Marc, do a cross over ep with David Tipton to rewind your transformer. Cheers Mate!

@kaunomedis7926 10 ай бұрын

I don't see a problem rewinding transformer. Learn this art in childhood.

@Gymnos2 10 ай бұрын

Seems like a cool project! Can't wait for the update.

@ray-kast 10 ай бұрын

hahah is that a custom spongebob titlecard?

@philmayf 10 ай бұрын

I know it's a crazy longshot, but it feels like there should be someone out there that understands winding custom transformers

@SeanBZA 10 ай бұрын

Easy to do, there are plenty of rewinders who will take that one apart, mark all the windings for turns, diameter and such, and then reuse the core, with a new paper former, to rewind the transformer. Easy enough, just that often it is cheaper to buy a new transformer, but for old ones that are not there rewind is the only option. Just look for local motor rewinders, and give then the transformer to do, and it will come back in a few days looking all new and smelling of fresh varnish. Plus also will have improved winding wire, capable of much higher temperature operation, and better insulation that is not paper based.

@keithmarlow 10 ай бұрын

@@SeanBZA Exactly, they can rebuild it...

@SeanBZA 10 ай бұрын

@@keithmarlow Yes, had a small 100W motor rewound, because there was no stock available, all 6 moths out, and as it was an extended shaft version, of a common regular split phase motor, rewinder it was, with new wire, and a few drops of oil into the bushing felts to keep them happy. Took around 4 days total, and it came to more than the price of a new motor that size, but again, no stock, and 6 month lead time from Italy for it.

@Readbooks6800 10 ай бұрын

I don't understand most things in your videos, but it makes me curious about electronics especially one which are old. I am learning things and would love to restore them in future. looking forward to the next video.😊

@gtoger 10 ай бұрын

I always try and fix my ohm problems before moving on to others.

@Agnemons 10 ай бұрын

Good to see Marc socking it to the dirt.

@ScottDotDot 10 ай бұрын

Augmenter l'accent pour les transitions! 😅

@ntsecrets 10 ай бұрын

You’re not going to try to rewind the transformer?

@c1ph3rpunk 10 ай бұрын

I’m mesmerized by how that oscillator works, and how apparently stable it is considering it’s basically just a couple light bulbs. It would not surprise me if it’s as stable as, perhaps more, than a 555 timer. Just because something seems primitive, doesn’t mean it is.

@Yrouel86 10 ай бұрын

I don't know if it's worth it but if you can't find a replacement for the burnt transformer of the other unit (if you's like to fix that one as well that is), shango066 in a recent video (d664czPzJi0) featured a guy in Poland that rebuilds/rewinds transformer. In other words with the parameters from the working one he should be able to remake a clone of it

@neilshep50 10 ай бұрын

That transformer was cooked like my wife likes her steak...............................burnt to a crisp 🤣 Recently seen the same colour on one of the sets of windings on a 3-speed induction motor from an air filtration unit. Someone never cleaned the filters so.......

@Hans-gb4mv 10 ай бұрын

That's no spoiler at the end, but something everyone following this channel should know ;)

@Derpy1969 10 ай бұрын

This is awesome. I did not know such tech existed for volt meters. HP made everything!

@SLeslie 10 ай бұрын

People can be fascinatingly unsmart. I have heard multiple sorties when individuals tried to measure with a 10 or 20 amps capacity DMM how much current a car starting battery provide by basically shoring the battery with the DMM.

@danielatbasementtech 10 ай бұрын

Thanks for sticking with this repair … always something for us to learn.

@websterleone 10 ай бұрын

I'm amazed you didn't replace the blown winding in the transformer with how far you go on some of these xD

@tomschmidt381 10 ай бұрын

I picked on up at a hamfest years ago but could never get it fully functioning so it went back to another hamfest. There are upgrade kits on eBay but are pretty expensive.

@624Dudley 10 ай бұрын

Love the DIY SpongeBob gag! 😄 Oh, and the whole rest of the episode too. 👍

@DerekHerbst747 10 ай бұрын

I wish someone would donate a HP VTVM to me, especially in a sad state. I love restoring old equipment!

@JeffreyLWhitledge 10 ай бұрын

I love the way this video includes a native French-speaker imitating Tom Kenny’s fake French accent. Awesome!

@Runco990 10 ай бұрын

I managed to score a newer (brown case) version of the 410C for well under the usual $10,000 asking prices on the auction site. It is near MINT!!! It has become my pride and joy for doing RF alignments. Nothing beats a moving needle for this. 😊 BTW, there ARE solid state replacements for the Photo Chopper for it and the 3400.

@scowell 10 ай бұрын

I was expecting to see a battery... the VTVM's I've opened have all had a leaking dry cell in them for ohms, requiring some battery holder cleaning. Lovely to see it come up and calibrate so nicely, thanks for saving them for future people to enjoy.

@SidneyCritic 10 ай бұрын

Someone ring FeedbackLoop, he hand rewound a 7 winding toroid - lol -.

@gerryjamesedwards1227 10 ай бұрын

This should be a useful addition to the lab. There are quite a few instruments of a certain age that call for a VTVM in their service manual calibration/alignment procedures.

@User-w7ckl 10 ай бұрын

2:24 I thought it was Grady from practical engineering

@chrisdooley1184 10 ай бұрын

Why am I not surprised you have a 1963 original catalog listing that meter 😂! I love this channel despite not having very much electronics background but I do learn something every video I watch so merci bcp Marc! Ce canal est mon préféré ❤️

@AmauryJacquot 10 ай бұрын

broken power transformer could be replaced with a modern design switching PSU ?

@janosnagyj.9540 10 ай бұрын

no way, too many different output voltages, and a lot of EMC noise problems...

@richardhole8429 10 ай бұрын

Could, maybe. Should, I hope not. Be like rebuilding a hamburger with veggieburger. Ok to do but loses its heritage

@KC9IEQ 9 ай бұрын

Encore! Encore! REALLY pleased that you have shown so much about optical choppers, I'm currently fighting a noisy Fluke differential voltmeter and suspect a chopper issue there as well. The "black magic" behind tuning these circuits is tribal knowledge, nearly lost to time.

@rallymax2 10 ай бұрын

I couldn’t work out what the orange clean up bottle was. Can you please share?

@CuriousMarc 10 ай бұрын

Ah yes I forgot to say what it is! it’s Brasso, metal cleaner / polish.

@rallymax2 10 ай бұрын

@@CuriousMarc I think my Brasso must have gone bad in some way. Every time I try it for cleanup it scratched the work - even with a fresh cloth and leaves a film that won’t hand buff off. Your use came out much more like I would expect - and have seen in the past when using it on dining silverware. Also, thank for the education on the probe having a 1MOhm resistance. I have a 1940’s volt meter and having seen your video I dig up the schematic and it needs the high impedance probe. I would have cooked it in restoration if not for your video.

@chriholt 10 ай бұрын

Oh man, I haven't used a VTVM since high school, when we built and used Heathkit (!) VTVMs in Electronics shop. Great memories!

@nathanraymond3899 10 ай бұрын

Hi Marc, I’m just finishing a MS EE degree at UVM, these videos are great, I love watching an experienced engineer ply there craft, and solve these problems, thanks and keep up the good work

@JulieanGalak 8 ай бұрын

Couple of years someone gave me an old, non-functional, Simpson vacuum tube VOM. This is really making me want to restore it.... But I've literally never dealt with tubes... I suppose the first thing to do is get a Variac, to power it on gently and see what's up...

@soothcoder 10 ай бұрын

You could re-wind the transformer (Feedback Loop style) :)

@mellertid 10 ай бұрын

I appreciate the explanation of the photo-chopper! But how does it not destroy the input impedance? At 60 Hz the LDRs wouldn't have time to reach high resistance, I thought 🤔

@DavePKW 9 ай бұрын

Another great troubleshooting video. I definitely learned something in this one. Thanks.

@blobscott 10 ай бұрын

15:34 Can someone explain the "Un-Chopper" part of the circuit? It looks like when the square wave is "high," it is fed to a capacitor to provide the final DC output level, which makes sense to me. That said, why does the un-chopper switch need to be reversed from the input "chopper" (as Mark mentions in his elevator explanation)? It seems the output "high" signal would be at the same phase as the input (post chopping) unless the amp sections are inverting.. Also, why is the un-chopper switching to ground when the output is low? This seems like it would draw current and reduce the voltage peak from the output capacitor. Anyway, I'm not very much with electronics, so all this is probably obvious to others here.

@MCPicoli 10 ай бұрын

Give the burnt transformer to someone interested in a small side project of rewinding it. Maybe an intern? Some local technical school? Someone from the KZbin community?

@twingoman2000 10 ай бұрын

Love your Work! It is so crazy to watch your skills, knowledge and understanding. Me personaly is also working on broken things but farcaway from your skills and knowledge. Good thing in your videos, most of your explanations are to understand and leads me to try to get better understanding of what might be the failure. I really love your Chanel!

@Stelios.Posantzis 10 ай бұрын

Great stuff! A bit sad that I only discover this 9 years after it was made... What happened to the defunct brother? Did you ever find anyone capable of repairing the blown transformer? It's not hard but it will cost mucho dinero...

@erickvond6825 10 ай бұрын

While expensive and time consuming it is possible to have a transformer rewound. Hence the second VTM could be put back into service. It's been awhile since I last used a service like that so I'm unsure where to send you for quality services of that nature. You might try looking into companies that rewind electric motors.

@benjaminhanke79 10 ай бұрын

I don't understand why the neons start to oscillate at all. *Edit* I found it: Wikipedia "Pearson-Anson effect"

@joes5669 10 ай бұрын

Your videos keep my attention until it's too late to give them a thumbs up. But they're so excellent that I go back to hit that thumbs up even if it means having to watch another commercial to get it done! Thanks!

@BlazeGelos 10 ай бұрын

Wow, I'm from Mexico and bought one of those some years ago at a flea market. I didn't knew how to repair it, but now it looks to me like it could have a problem with the photochopper too, I thought that the neon bulb assembly was actually some kind of a rare vacuum tube lol. I like a lot the way old electronics stuff looked and how they operate so i'll try again, maybe I can finally bring it back to life too. Thanks for the video.

@Renville80 5 ай бұрын

I enjoy this channel and the way you dive into technology of decades past. May I make a suggestion for your elevator music sections? When you show the slides, can you have the title on top of the screen instead of the bottom? The reason I ask is that since I can't hear, I use the closed captions, and so some information gets hidden behind the captions. Just a tiny quibble, but otherwise I love the content and method of presentation on these videos! 👍

@glitchwrks 10 ай бұрын

Nice to see one with an intact scale! I've got a number of HP analog meters in this case style that have *very* peely scales, including a few mirrored scale units :/

@markjurkovich7814 10 ай бұрын

Where's your Carlson super probe? That'll fix it. 😉🤣

@Powertampa 10 ай бұрын

I was half expecting a "how to wind your own transformer" interjection by someone who you know has way too much time on their hands. :)

@guyh3403 10 ай бұрын

in-cre-di-ble ! Thank you so much for these video's.

@RingingResonance 10 ай бұрын

build a custom switching power supply for the other one!

@therealjammit 10 ай бұрын

The blown transformer doesn't look too difficult to re-wind. At worst you have a working one to reference, even teardown the working one to get wire gauges.

@anthonyhart7878 10 ай бұрын

NGL, ive never considered using brasso to clean things...

@Ozymandiuus 10 ай бұрын

I would have loved to watch the whole video, but the shakiness on the hand held camera made me sea sick, so I had to bail after 5 minutes. Most of your videos are not quite so wobbly.

@richardmerifield3263 10 ай бұрын

Is there a modern replacement coaxial cable that someone could recommend? My cables are cracked and brittle alone the whole length and need replacing. Something flexible but also the same diameter would be great.

@sloth0jr 10 ай бұрын

I would actually be really interested if you had any way of rewinding the trashed transformer.

@douro20 10 ай бұрын

I didn't know the 410C was a VTVM- I always thought it was a FET unit. I thought about building a probe for my old Sylvania VTVM- it needs a special tube with a 125mV filament which is almost impossible to find- but I intend to modify it so I can use a small acorn diode.

@CuriousMarc 10 ай бұрын

@douro20 Like the 400E and the 3400, I think there are two versions of these, the early ones with tubes and the later serial numbers with FETs. Good luck with your AC probe!

@nicolasgoldberg3114 9 ай бұрын

Hi Marc, great job on restoring the vtvm and thank you for sharing ☺️

@hinz1 10 ай бұрын

Job for the dishwasher, when wife/gf isn't looking ;-D

@nrdesign1991 10 ай бұрын

I accept your apology for the sound but i cant bear the loud noises.

@HappyDiscoDeath 10 ай бұрын

"If the women don't find ya handsome, they should at least find ya handy!" - Red Green

@genetomblin2883 6 ай бұрын

I have not seen one of those giant AC probes in a very long time. Well I am an old man, so these things are to be expected as long as my memory holds up.