HP 6516A 3kV Supply vs. CRT Tube

Will our HP 6516A 3kV power supply finally manage to light up our mystery CRT tube?
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[@video99couk]

I built a 25kV probe for TV repair work, based on a design in Television Magazine back in the day. It's housed in plastic trunking and consists of a resistor chain and a small moving coil meter. It works and never tried to kill me. When I next come across it I'll have to demonstrate it on KZbin.

[@russellhltn1396]

I'm betting that oil came from the cap of a different power supply in in the pallet. It might be one of the ones you haven't gotten to.

[@CuriousMarc]

I thought so too, but then I was told that oil from oil caps should have a very strong smell. This had no smell at all, so it was probably just regular oil from somewhere else. But I'm just guessing.

[@diskettenfett3161]

@@CuriousMarc It's a smell you can't unsmell, like nothing else, and it will stick in your nose. Hard to describe, slightly 'fruity-musty' smell I would say. Once you know, you will smell leaky PCB caps from miles away. ;)

[@CuriousMarc]

@@diskettenfett3161 Thanks, this is very helpful. Definitely not that then. I also went through all my supplies, three had a fallen meter and about the same number a bad front switch, but they all worked, and none of the caps did leak. So confirmed not being oil from another supply either.

[@jlwilliams]

If it keeps leaking oil, you'd better send it off to CuriousMarc's Garage. It'll probably need a clutch job by then, too...

[@Mat_1000]

@@diskettenfett3161 I don't know anything about this kind of oil or electronics, but for example, vegetable oil like Olive oil, if you let a thin layer of it outside, after some time, it doesn't smell anymore. Is this kind oil smelly like for tens and tens of years? I was wondering, as in the video, the mystery is that the oil in on the back left side of the device, and the oil capacitors are on the back right side of it, couldn't it be that the device was stored on its left side when the leak happened, and so, made the oil leak on the transformer and at the bottom (on the right side of the case) ? (which could explain the oily screws outside as the oil would have infiltrated through the holes). It's just the thought that came to my mind while watching the video, but again, I don't know much about electronics so I might have said something really stupid :D

[@bobweiss8682]

You are right to be concerned about those caps. The ones in the rear are marked as Sprague "Clorinol" types, which was a tradename for PCB (polychlorinated biphenyl).

[@douro20]

That's what I was going to say.

[@Sixta16]

if it is a cap with PCB oil, it will likely still work century old. Unlike those modern eco variants.

[@douro20]

@@Sixta16 Yep

[@skfalpink123]

Just seeing a 3KV power supply being turned on by hand (and not by a three foot-long PTFE pole), makes the hairs on the back of my neck stand up..

[@deansundquist9601]

With every new episode I repeat the following along with Marc, “If you follow the channel… ” please never change 😀

[@rav3nx33]

I was working on a junction box on a helicopter when one of the other engineers why they needed so many relays in there for it's particular function; I replied "I'll need elevator music to explain that"....but he didn't get it. But we do; and that's what really counts 😝

[@fburton8]

"I now have a whole bunch of high voltage bias sources, so why don't we try to..." wire them up in series - was what I _thought_ you were going to say. 🤪

[@CuriousMarc]

I thought I could do that, but alas, the highest either supply output can be is 4 kV above ground.

[@Zerbey]

Some terrifying voltages you're dealing with there, glad you've got the knowledge and experience to be safe so we can watch and learn!

[@albinklein7680]

6mA is not that dangerous. But it hurts a lot nonetheless. The danger starts with electrophoresis power supplies. They are quite popular with hobbyists because they are cheap. Some of them put out 30kV with tens of milliamps. And you can parallel them... Those can knock you off your feet pretty bad.

[@KeritechElectronics]

Lightsaber sounds made my day! Modern engineering solutions (3D printing) just fade in comparison with the good old hot snot, haha. Beautiful is better than ugly... but simple is better than complex, complex is better than complicated. Nice CRT collection :)

[@nophead]

It needed to be printed with something less brittle with better layer adhesion, perhaps Nylon.

[@rpavlik1]

Or sla

[@nerddub]

no that was just not the correct material or orientation. There are many ways to overcome this, I could have made that part actually work using any of like 10 techniques in 3d printing. Hot glue has it uses, but let's not be crazy and say hot glue is better than the whole of "modern engineering solutions"

[@leon545b]

One note of caution when using a hv probe (I have a 1000:1 B&K probe) with an auto-ranging DMM. I managed to fry the mV range on my Fluke 79 by probing an oscilloscope CRT power supply (~8 kV) b/c the meter was initially presented with zero volts, it was on the mV scale. I suspect that when I touched the probe to the hv point, the capacitance of the probe allowed a brief significant overvoltage to reach the meter. From then on, I've always manually selected the range when using the hv probe, and I've not had a problem. I noticed that when you were using your homebrew probe, you started out low and slowly went higher, which also avoided the problem.

[@Sixta16]

Does not sound probably. If there are caps as to frequency-compensate the voltage divider in the probe, then I would expect them to incorporate in the design a series peak current resistor as to exactly limit this phenomena. On the other hand the Fluke 79 is a decent meter with solid protection on inputs, so hard to suspect as what have gone wrong.

[@Lemon_Inspector]

I admire the courage to play with the very angry pixies, and the skill to not get bitten by them.

[@2packs4sure]

If those old capacitors have been leaking oil you would have smelled it,, it's a powerful smell...

[@ehamster]

I think I prefer “Squeeky Marc”, can you edit your normal voice so that you always sound like a chipmunk?🤪

[@TheDiveO]

when Marc "the Sparc" talks about a stack of 3kV supplies, better take that electrically, never as a figure of speech.

[@matthaxx7137]

I know its not nearly as much fun, but I used to fire a camera flash at CRT screens to check the colour. If you do it in the dark and try not to get blinded by the flash, the phosphor persistence is usually long enough to see the colour.

[@spagamoto]

Thanks for sharing. I love arcane knowledge like this!

[@Turboy65]

A UV LED also works...

[@paulstubbs7678]

This reminds me of a time when I tried to light up a TV crt using a spark supply I had made. The spark gen could throw a 6cm spark, so I figured I could generate a spot on the tube. The only other supply was a small regulated supply I used to light the CRT's filament. Unfortunately the spark gen pushed the filament supply many KV above ground causing a flash over to ground and a fried LM301 op amp. I killed my variable supply and never got a wink out of the CRT. I didn't have any grids connected, I was trying brute force and ignorance.....

[@TheUglyGnome]

Just put the tube into the Alto and have the World's only Alto with amber display. How cool would that be?

[@thesteelrodent1796]

believe they're going for authentic

[@TheUglyGnome]

@@thesteelrodent1796 IKR. My suggestion was mainly tongue-on-cheek kind of thing.

[@Stoney3K]

Those tiny CRTs could make great vector displays if you feed them from an analog synthesizer or even just a sound card.

[@compu85]

Hm dang, a horrible amber CRT. If you need to get rid of it I can give you a shipping address.... :) PS: if you try the same experiment on a worn CRT, you'll get a different shape on the spot! It will be a lot dimmer in the middle.

[@mysock351C]

I have yet to have the nerve to really mess around with my 3kV/1.5kW adjustable lab supply. I’m guessing if I screw up it kills like an MOT, but with much greater precision.

[@AngDavies]

Oof, half an amp, and the voltage to drive that. Would probably be even worse than an MOT if DC, same result but slower :/

[@RingingResonance]

I love the orange CRTs! I'm waiting for the day to come across a monochrome blue CRT of that size.

[@jakeparr4532]

Oh my goodness I am so excited to see the next episode! I want to test an oscilloscope CRT and now I'll know

[@rkirke1]

I just recently built a DIY 4kV PSU and voltage divider/meter to drive a 70kV voltage multiplier I made as therapy during the COVID lockdown (Soldering up CW multipliers is like cross stitch for electronics nerds!). This video makes me want to find an e-waste CRT TV and play around - CRTs used to be black magic for me as a kid, but I'm pretty sure I'd understand the intricacies these days. Thanks Marc & the rest of the team for all your work making these videos. As always, keenly awaiting the next episode!

[@HfLuo]

Haha the meter bezel... I bet you got the STL file from grabCAD. I recently got a HP 6111A power supply which uses exactly the same panel meter, and also missing the bezel. I almost sent the STL file for SLA printing, until I found out it was for larger meters. Still don't have time to measure and draw one though, and I believe that SLA printing will be much more reliable than FDM here.

[@DaveRepairs]

I WAS impressed - im arcade engineer and we lose maybe a lopt / board a week so was very interesting as lopt as starting to get harder to get

[@Drmcclung]

Careful with the oil filled caps, 50/50 chance it's PCB coolant (polychlorinatedbiphenyl) and that stuff's nasty

[@dougmcclelland6139]

Most of these old small CRT will work with about 10 - 12 KV. they are just blank and white. i remember my first experience in repairing a color TV. the anode is about 24 - 30 KV. I turn it off but forgot to discharge the CRT at the HV connect near the aquadag coating. It knot me across the floor with a 'Ouch '

[@Nf6xNet]

For simply determining the color of a monochrome CRT's phosphor, does shining a UV light on them yield the same results as exciting the tubes normally? In the small number of CRTs I've shined my UV flashlight on, I think they appear to glow their normal color. I can even see the screen burn from the graticule on my HP 8560E. Naturally, exciting them normally is more impressive and it demonstrates that the electron gun is not dead.

[@CuriousMarc]

No, it does not work except on some older low voltage scope screens. But not all of them either.

[@SidneyCritic]

Gee, I didn't expect 2KV to work, ie, I thought it would need 10KV at least.

[@Turboy65]

I propose that you turn this into a progressive instructional series. How to go from making a CRT glow to actually building a working television circuit to drive it. You have basic CRT functionality, now put a deflection yoke on it and start driving it with horizontal and vertical signals Build a basic B&W TV circuit one circuit section at a time. Of course this would be analog NTSC TV. That's fine.

[@bobwatkins1271]

Back in the day, we were designing a computer with a bitmap screen similar to the Alto. The intention was to use a white phospor, but for Germany we had to use amber phospor because their OSHA-equivalent regulatory agency required it.

[@CuriousMarc]

Interesting. Maybe we put the CRT in the Alto after all and call it a German Alto...

[@albinklein7680]

If one of those power supplies starts to smell like a slightly rotten pineapple; get it outside the building. Quick. PCBs are nothing you want to be around in a room. Even if my father literally bathed in that stuff in the 60s and just turned 85.

[@rz350lc]

Alanis Morissette probably had it right with regards to high voltage experimentation : "'Cause I got one hand in my pocket and the other one is playing with high voltage." Thanks for the amazing content over the years. Got zapped as a teenager removing the fat red lead on a CRT.

[@kovacsdavid4362]

Hey Marc! I just wanted to ask what's the name of the intro tune? I'd love to listen to it's entirety! Otherwise, great video! I would be scared to deal with anything that has high voltage in it...

[@prillewitz]

I remember my first tv repair when a high voltage transformer sprayed which could easily been seen in the dark. Scary to replace the transformer but very satisfying when image is as bright as a new tv!

[@christopherkise]

A tip is to use rtv silicone / small amount of tech7 insted of hot glue. As the hot glue is to often not gluing well. I think there must be many different types of hotglue, but the types i have releases easy :(

[@CuriousMarc]

Or E-6000 maybe. Hot glue really a band aid for now. Although I have hot glued panels in my R2 and they have not come off!

[@paulstubbs7678]

Never had much luck using hot melt to thick metal surfaces - like front panels. Silicon would have been my choice, although a pain to remove.

[@jonathanhendry9759]

@@paulstubbs7678 Maybe pre-heat the metal with a soldering iron so that it doesn't cool the glue too quickly.

[@enoz.j3506]

I remember back in the repair days,carrying a crt from the stores to replace one on my bench,got one hell of a zap from the anode cap socket,i was told that over time the crts charge up and can have a few kv on them,without being powered up!!!! ,static in the air charges them,well they are one big cap afterall.Then on i discharged them in the packing box,before lifting them out.

[@radarmusen]

Maybe the oil was coming from a upstairs living hv-supply there had a little accident in its pre life.

[@martin_racz_a_szerelo]

What's the outro song? I'm seriously asking it! Pls answer.

[@omarcusihuaman4261]

Hello, i know that tv crt works with yokes to deflect the beam. Do you think it would be posible to add an external Plate?? Made with regular steel sheet to deflect the electron beam?

[@JohnDoe-yj5ng]

For a moment there I thought you had a green CRT monitor for a NCR ATM machine!

[@Veso266]

Could you try to draw some lines on a crt? Maybe draw the whole frame orange? Also why is the dot so big, isnt a dot on a crt normaly tiny

[@ДмитрийСыроваткин-м7ю]

Hi! Can you make an amplifier from CRT? It will be a wery interesting.

[@jaut-76]

If your on about a audio amp it won’t work. This is because a crt is only meant to display pictures

[@ДмитрийСыроваткин-м7ю]

@@jaut-76 It's too bad, because CRT is a modyfited tube. Soon my friend will give to me a 2 CRT TV set's, & I try to use a CRT in a different tube modes: as a triod, tetrode, penthode & in full CRT mode: uslng a secondary winding of fly back transformer as speaker load...

[@mrnmrn1]

I heard that you can use a VFD as a triode - a very crappy triode, but it works. I want to try this since many years. I don't think it would work with a CRT, but might worth a try.

[@overkillaudioinc]

LOL I wonder if that was the file I made for HP meter windows?

[@SuperAWaC]

I dunno why you're concerned about orange. it is the best crt color.

[@HappyDiscoDeath]

8:21 reminds me of Fran Blanche finding green schmoo in her guitar amp from one of the power cord wires

[@fabiosemino2214]

My experience with HV is limited but I replaced a HV cap for a microwave oven, it leaked this very thin oil just after 23 years of almost continuous use. I guess the last roast was fatal for it.

[@fischX]

The experience someone can have with high voltage while alive are limited anyway ;)

[@packratswhatif.3990]

Well that just brightens up my day !

[@RetroJack]

This video gave me more anxiety than the entire AGC series!

[@Txloganc]

I believe that is an Amber phosphor not orange

[@jurjenbos228]

"If it doesn't work, apply more voltages". The electronic version of "If it doesn't work, apply more force".

[@mansnilsson4382]

Oh my, I FINALLY found an area where my lab is better equipped than Marc's. A year or so back I got hold of a never-issued ex-USMC Fluke 27 kit with RF probe and, not one, but two! HV probes; 6kV and 40kV, all in pristine condition. Have only used one of them to check the HV supply of my 465 scope, so far. I trust this is not going to last as a proper probe is on order.

[@rav3nx33]

Interesting topic, I'm an 85 baby, so I only caught the end or CRTs ; it's always been scarey dark magic to me. 🤪

[@graealex]

I'm from 83 - and I still have a big sucker in the basement. They were sold well into the 2000's.

[@rav3nx33]

@@graealex oh yeah I defiently had and used them, never worked on them though.

[@clonkex]

I'm from '95. We only had CRTs in our house, even a large flatscreen one (which absolutely required two people to lift). Then we got a 3D LCD (LG, I think) and never looked back :P

[@simonkormendy849]

From what I seem to remember, CRTs also generate X-Rays as well as visible light if they are operated at their normal voltages.

[@BobHannent]

Usually at the higher voltages, like 22kV, I don't think it would emit much at 3kV

[@graealex]

@@BobHannent The energy spectrum emitted is proportional to the acceleration voltage. As such, at 3kV you only get low-energy X-rays which are easily stopped by the glass. Color TVs that operate at 25kV need to have lead glass fronts as they emit considerable amounts of high-energy X-rays.

[@hughgilbert390]

@@graealex The funnel would be leaded but the face is strontium glass because leaded glass turns brown from x-ray exposure.

[@graealex]

@@hughgilbert390 Oh, didn't know that. Thanks, you're absolutely right. Lead only in neck and funnel.

[@PixelSchnitzel]

This may be a dumb question, but could you also hit it with a UV laser to see what color the phosphors are? Works with my white & blue phosphor CRT's. Not sure if that'd work with orange or green. Also, thanks for showing the improvised HV probe! That worked great! I need one, but only for 600 - 1kV. I'll be sure to take your advice and NOT build one of my own. ;-)

[@t1d100]

Yes, good, scary fun.

[@eddiehimself]

Ah yes, a Cathode Ray Tube tube :3

[@hughgilbert390]

The breakthrough voltage requirement of aluminized CRTs is normally around 2-4kV. Less than that, the electrons don't have the energy to penetrate to the phosphor and light up the screen.

[@maicod]

13:26 you recreated the sun there :)

[@davidverbeek4849]

an orange alto would look super cool

[@rosalinafarias2757]

Be careful, your going to burn a hole in the screen because of no H and V sweep.

[@CuriousMarc]

Indeed! Which is why we explain and show how not to do that in the video.

[@fugelkusch3722]

8:33 Maybe someone greased the power supply from the outside so that the power animalcules can move more easily ;-)

[@Very_Dark_Engineer]

With some voltage levels on CRT electrodes you can get catode surface picture on the screen and judge about catode quality.

[@jonathanhendry9759]

I wonder if that was my bezel model from Thingiverse, or someone else's. Yeah, it was too thin and weak.

[@CuriousMarc]

It's yours!

[@jonathanhendry9759]

@@CuriousMarc Sorry it didn't work for you. Same thing happened for me, as you would expect. Was just thinking maybe extremely thin strips of metal, glued to the plastic, would be enough to strengthen it. Or hot glue works a treat.

[@alainblazit9504]

Pour connaitre la couleur d'un CRT vous pouvez l'éclairer avec une LED UV. Je l'ai fait avec un ancien oscilloscope pour tester la LED.

[@Jkauppa]

capacitive voltage divider with full bridge rectifier + output capacitor stabilizer = capacitive dc regulated power source

[@Jkauppa]

if you add a transformer stage in the beginning, you get a transformer voltage divider amplifier, should be very frequency independent

[@Jkauppa]

tunable capacitor voltage divider amplifier

[@en0n126]

Neat. I am looking forward to your CRT videos.

[@HappyDiscoDeath]

7:31 that's Schmoo!

[@jonathangauci2182]

I have 5.5 inch color crt, how much kv i need?

[@AchhcityNoob]

i think u should the specs on google

[@FUNKLABOR_DL1LEP]

GREAT! 73s..

[@zibobpompon5768]

Can you please give the link of the elevator music at the end ? Nice day .

[@benmodel5745]

Lol I also used hot glue to hold in the panel meter of an HP power supply that had the same bezel break.

[@projectartichoke]

It might be possible to check phosphor color by exciting it with a moving green pen laser.

[@brendanbarbour8568]

Excited to see those old CRTs come to life. Marc, can you tell me where you ordered the High Voltage probe...I need one for my vintage Clare Insulation tester. Thanks in advance.

[@CuriousMarc]

Mine is a 40 kV Fluke and is off eBay, plenty available. You can also order them new from just about anywhere.

[@jerryeiting5367]

CRTs excited by high voltage can generate X radation, so be careful with experiments!

[@johnopalko5223]

The relatively low second anode voltages on these tubes (3 kV) aren't likely to produce a large amount of x-rays and the rays they do produce are likely to be very soft. The tubes you have to worry about are the huge old color television tubes with second anode voltages of 30 kV or more. Even then, you're likely to get more x-rays from the HV rectifier and the focus rectifier than from the CRT.

[@CraigPetersen12f36b]

I had one of these about 30 years ago. I sold it for next to nothing because at the time I didn't have a way to put it to practical use. However now I do and am picking up another one.

[@graealex]

Sell low, buy high I guess.

[@JoZf_Gibson]

Merci

[@624Dudley]

You’re right, scary fun!

[@diskettenfett3161]

Yay, CRT fun! :) I love it!

[@shamrock1961]

Marc these vignettes are too short!!😪😢😥

[@simonkormendy849]

If it uses electrostatic deflection, you should be able to move the spot to other parts of the screen by applying voltage to the deflection anodes.

[@danmenes3143]

That looks to me like a magnetic deflection tube. As I understand it, electrostatic deflection can only develop a small deflection angle, which is why oscilloscope tubes are so long compared to their screen size.

[@王昱-s3x]

The power of kilovoltage....💪

[@joswhite7923]

Wow, shades of tv in the earlies.

[@marvintpandroid2213]

Them some very angry pixies.

[@lachlanlau]

Orange CRT is cool

[@aaronr.9644]

I wouldn't have had the balls to do it :)

[@zaprodk]

An Amber tube - The coolest one!

[@boonedockjourneyman7979]

Thank you for this.

[@68hoffman]

kool

[@yorgle]

CRT Tube? Cathode Ray Tube Tube?

[@CuriousMarc]

Yes yes that's what it is is

[@Xaerorazor0]

Mmmmm high voltage.

[@ДмитрийСыроваткин-м7ю]

Sorry: very.

[@AiOinc1]

3kV is really low for anode voltage. If you get light, I'd be surprised. Even small B&W ones like 9kV+ to make light and more for good focus.

[@CuriousMarc]

It’s very low indeed. This CRT normal acceleration voltage is 17.5 kV! But for a quick phosphor test, 2 kV was apparently plenty enough.

[@olik136]

he said in the video it started lighting up at 2kV- and they only needed to see the color of it

[@tipetu]

Isn`t filament voltage for CRT normally 5V?

[@bobweiss8682]

Usually 6.3V.

[@paulstubbs7678]

I've mainly seen 6 or 12V

[@tipetu]

@@paulstubbs7678 Yeah that`s the norm on "small" tubes, but all the CRT`s beeing tested on Shango066`s channel are tested on 5V. He has a quite interesting channel and know a thing or two about old TV sets.

[@bobweiss8682]

@@tipetu Normal operating voltage is 6.3V. The 5V is applied as a "life test", to see how quickly emission drops off with cathode temperature.

[@tipetu]

@@bobweiss8682 Interesting, thanks

[@TechGorilla1987]

I have had some luck reinforcing 3D prints using very thin piano wire melted in to the plastic using soldering iron or current.

[@jonathanhendry9759]

That might be difficult in this case, because of how thin the part is. Perhaps it would be possible to glue a very thin strip of metal to the plastic.

[@ericblenner-hassett3945]

It would be fun, albeit a bit lengthy, to add an Arduino Pico to drive the horizontal and vertical coils to show a static image ( or animated ). They can do the signals for VGA signals and having the IC do the timing directly for a tube should actually be easier. I recommend The channel logo as a test, especially for the round CRT that was previewed.

[@BTenbergen]

Months ago, I found this channel and have been following it religiously, so to speak. I’m impressed and a bit envious of the sheer ability Marc et al. demonstrate. Today, I’m relieved that they are not above hot gluing stuff together when it won’t fit. I feel a bit vindicated. (In other words, thanks for the great content and teaching and old chap some things.)

[@HA7DN]

Amazing! I was a bit suprised that it light up with floating grids & anode, but I got even more suprised when it worked with a grounded G1. Most CRTs I have read the datasheets (all scope CRTs, electrostatic deflection and small angles) needed a negative voltage at G1 to even light up, and with a grounded (rel to cathode ofc) G1 they would just cut off.

[@HA7DN]

Edit: Just uploaded a video on the topic. My CRT is quite a bit smaller, but it's quite a cute one!

[@explorer914]

First? 🙂

[@CuriousMarc]

Yes, you are first says KZbin! You are awarded tired orange vintage photons emitted by undervoltaged vintage CRTs…

[@TechGorilla1987]

Second.