Rejuvenating a Macintosh CRT with equipment from 1969

[@greedj]

I used to be a TV repair guy back in the 80s and 90s (I'm now a computer engineer). I used that exact tester (B&K actually sold additional updated modern adapters for a while with updated cross reference guides). I rejuvenated many many CRTs with that tester and I would estimate about 75% of the time the CRT remained functional for years after. The other 25% of the time there was either no change or the CRT would completely fail. The spark you hear is normal when rejuvenating and I had the best success using 3 quick taps in a row and then checking emission. It is not doing anything to the heater, it is causing an ARC across the electron gun (usually visible when pressing the rejuvenate button) that exposes fresh surface on the coating of the cathode.

[@filter4now]

Thanks that answers my question. Is the heater necessary at all in the rejuvenating state or just when actually testing emissions or watching the CRT?

[@andymouse]

" Rejuvenation" means increasing the filament current a bit, and or more extraction voltage to "blow" any surface crud of the filament and basically increase the amount of electrons liberated from the filament, this works and is used in old electron microscopes as a last resort before looking the customer in the eye and telling them how much a new filament is ! however filament lifetime after this is a bit of a lottery, also there is a risk that the crud (filament) you removed went further in and caused problems down the line, so all in all, in your situation you did the right thing and you couldn't replace the filament anyway..i'm betting you get years out of it ! and from now it could actually improve a bit more...I'm a "glass half full guy"...cheers.

[@TheEmbeddedHobbyist]

just what I was going to say Andy, years ago a friend had a tv rental company, which would rent tv's cheap to people who the main stream rentals would not touch. The sets were ex rental which I help fix up, good clean inside and out and a tube boost would see them running for up to about a year, only had to last 3 months to pay for themselves.

[@luminociter]

So I guess this is the old extraction potential trick due to surface degradation... I have seen people use this also in old filament gas displays that are no longer produced and used in traditional lab instruments from the 60s to 90s... I guess the filament gets worn out during the process and the times you can repeat it is limited. Nice to see it working though, would be cool to also know what voltage/current it applies during this process.

[@SidneyCritic]

@@TheEmbeddedHobbyist Did you have to hit the button a lot, or just enough to get to good. Basically will more blasts make it better.

[@tekvax01]

@@SidneyCritic, if you hit the grid with HV too much you can completely destroy the CRT!

[@EsotericArctos]

It does work but you never know how long for, but even if you only get another 6 months out of it, it only cost a little bit of time.

[@patrickbuckland5849]

Truly fascinating stuff. And good to see you using Crystal Quest (which I wrote)! Electronics were my original passion actually before getting into programming mainly because I couldn't afford electronic components or test equipment as a kid. Then I realised that I programming was my calling. I was 22 when I originally wrote 'Quest. Currently working on a new version :)

[@mitfreundlichengrussen1234]

you have cost my brother and me several months of productive life - we played on a Mac Plus, the high score was around 1.7 million points and seemed to be unbeatable in the first week - until - I came home and my brother laid 2.1 mio. on me - at the end we reached something over 21 mio points, the game was so slow on the Mac Plus (because there was so much graphics going on) that one game lasted about 6 hours or more ... We´ve both learned a lot about addictions. What a great game it was, cheers from Southern Bavaria, where the beer is cold and the girls are pretty.

[@69Dartman]

I used to repair TVs back in the crt days and I was given a Beltron crt rejuvenator that was beat to death but still worked by one of the repair shops I got my sets from as their customer rejects. I made a pin adapter setup I could put on any newer crt and it increased my decent looking set output probably 60 percent because I could bring back marginal tubes to looking like new again. There is really a art to using one so it doesn't blast the guns too hard and it goes backwards and dies quickly. Some sets and the tubes they used almost always turned out great after usually just a cleaning cycle. Zenith used to have really good quality tubes that had a lot of emissions materials on the guns and usually a quick cleaning would bring them back, if not do a rejuvenation and do it similar to what you did. Push the button for a sec or a quick hit and see the crap blow off the guns with a light show inside the neck. Sometimes it would kill it, many times it would bring it back. Then you push the emissions button and watch how long it takes the meter per gun to drop to zero. The longer it holds, and if they dropped fairly evenly the better it was. If all the guns show the same level of emissions and its way up in the green the better. If one gun is way higher it would be hard to get a balanced black and white picture and the colors would be tilted towards the best gun. I much later found a totally rebuilt and fully updated Beltron on eBay for like 25 shipped in the early 2000s and last set I used it on was a 36" Sony HD set my mom had been given several years ago when it was looking horrible. It did bring it back and I was very careful but true to every Sony tube I've done it lasted about 6 months and was awful again. That Beltron had every newer crt socket adapter available and some internal upgrades and complete new manual for the newest tubes out before everything went lcd flat screens. I also have several military and high end tube testors and bixes if tubes I collected to repair TVs back in the day. I'm actually local to Portland if you ever run into needing any old tubes tested or a different crt testor to play with. I knew when I bought that last Beltron that I probably would never or very rarely use it but I couldn't let it go for the money and everything it could do. I MAY even have one of those B&K testors just like you have, but I didn't like it as well as the Beltron I knew how to use. I can't remember what I did with it but it may still be here stashed in my shed with the others. Shango is the man when it comes to troubleshooting any old stuff and getting it running, or restoring it if it's worth it. He likes the B&K rejuvenators best and has a Beltron as well he occasionally uses but every one likes what they are comfortable with so if you understand how to use it they all can work. Not many shops or repair guys do component level repair, they just replace the bad board and see if it works these days. That was fun to watch and brings back memories of all the sets I fixed.

[@ltdees2362]

🤣...someone mentioned they had used one of these "crt rejuvenaters" I have one also and would give it bout 60% success rate back in the day, saving your customer considerable expense...also, if this was the only repair and the customer had brought the TV to my shop, I would not charge them...Back in the 60"s we generally made house calls as TV's were just to heavy and bulky to load up and take to a repair shop...I had my tube-case, VOM, solder iron, cheater-cord and few basic tools...$3 house call plus parts...the good times...

[@andymouse]

yes they were.

[@Starphot]

Yes, been there, done that. My buddy and I opened a shop in his garage after serving in the military in 1977. We made house calls in the late 1970's. 10 bucks. This lasted a year until we went separate ways due to other opportunities and overhead costs. Also we bought our rejuvenator and a tuner tester from another small shop going out of business. Most of the mom and pop repair shops went out of business as 1980 approached. If you have to move the console TV sets, that meant you will have to go over the solder joints and burn test the TV for a day before sending it back to the customer. The point-to-point solder joints go bad over time due to the heating and cooling of the filaments and the current draw within the tubes. A little better with the semiconductor boards.

[@Walczyk]

wow i wish i could learn this art today

[@mr-meek]

@@Walczyk You can if you really want to. Check out Mr Carlson's Lab, Glasslinger, Shango006, Uncle Doug, etc, etc... so many resources =)

[@okaro6595]

I did not even know there were any such thing. All out TVs broke other ways than becoming dim. They might have been likely fixed but there always was new technology that made purchasing a new one attractive.

[@jjock3239]

Great video. An excellent site to watch for old electronics, is Mr Carlson's Lab. I know there are many more, but he is my favourite. A very close friend of mine, long since departed, spent his whole career, from the early 50s, as radar tech and instructor in the RCAF. After he retired, to keep occupied, he made a hobby, then a business, out of repairing tube type and solid state TVs that other techs had failed to repair. After restoring life to the TVs back to life, his last trick was, to use a version of a B&K rejuvenator similar to the one you have, to attempt to improve the brightness of the CRT I used to marvel at what he could bring back to life. As some of your other commenters have mentioned below, his success rate using the rejuvenator was about 75%, and this step was probably going to be enough to last the operational life of the TV. I had to chuckle, when I saw that you had blown a capacitor on the rejuvenator. I still play with a lot of old crap like that, (I am still using a tube type Tektronics 545b scope as one of my toys), and the first thing that needs to be done with those old beasts, is to re-cap them. If they haven't been used in a long time, I also plug them into a variac, and warm them up on a lower voltage, to allow the capacitors to re-form. That way, a lot fewer components (electrolytics) fail and require replacing.

[@MatroxMillennium]

Combining two of my major hobbies: Vintage computers and vintage television repair!

[@luke9511]

these things are used a lot by people who work on and repair and restore old arcade games and they have had good results with it

[@AiOinc1]

They're also used a lot by people in the vintage television community who knows their intended purpose is a band aide until the shop has a new or rebuilt tube ready for the customer.

[@AdolphusOfBlood]

@@AiOinc1 What does rebuilding one entail?

[@lelandclayton5462]

@@AdolphusOfBlood They leak the Vacuum out of the CRT slowly, cut the tail end off and remove the Gun assembly. In some cases they even remove the phosphor and put in a new layer. Add a new Gun assembly then put it on what looks like a lathe and heat the glass tube to the new tail end and slowly create a new vacuum. kzbin.info/www/bejne/jWSqaJVjeciChZY

[@krnlg]

@@lelandclayton5462 Wow, I hope they're still doing this. Its a pleasant surprise to see that people might actually still be making/restoring CRTs in this way!

[@thomassmith4999]

@@krnlg The people that have the equipment in that video have since (recently) successfully rebuilt a tube using it.

[@dschult3]

When you hit the dynamic intensifier button for the first time, someone started up their lawnmower in the neighborhood while I was watching it. That threw me for a loop for a second there!

[@adriansdigitalbasement]

Ah funny I didn't hear that while editing. Good ears!

[@alancordwell9759]

Where I used to work we used to get 12in B&W CCTV monitors coming into the shop that had been sitting switched on 24/7 for decades, some of the CRTs were so bad you could hardly see an image at all (apart from the permanently burnt on one of course!) so we used to 'give them a zap'. I would have said that 8/10 of them came up to a perfectly usable level of brightness, and a few came up like new. The 'repair' was permanent enough for it to be worth doing and it saved the cost of a new CRT. Loving this series of videos, Adrian. Best wishes from Sheffield, UK.

[@adriansdigitalbasement]

Cool! I can see that if this was a TV that you used 10 hours a day every day -- the fix might seem temporary, but for something like a retro computer which only sees occasional use -- even 1000 hours of bright image might last me 20 years. :-)

[@nuclearmonster]

Love this episode and seeing that wonderful old tester still working and helping that slightly younger tube come back to life!

[@blueribb99]

We used a B&K 467 Rejuvenator for many years. We had very good luck bringing dull CRT's back to life.

[@grantbyers7625]

Fantastic! We had an old Rank Arena set rejuvenated in the mid to late 80's. It lasted another 30 years.

[@FalconFour]

oh this is so cool to see. I recently got an RCA TV from 1974 that was apparently put in storage as it stopped working - no red. That experience familiarized me with CRT rejuvenators. I got a Heathkit tester/rejuvenator off eBay for $100. That fixed it right up, good as new! But mine had very specific, meticulous instructions for use, and I followed every step. It had two modes - cleaning and rejuvenating. Cleaning is what fixed the gun, rejuvenating brightened and sharpened it. On mine, you hold the function button for much longer, as you adjust the heater voltage. It had a lot more features than this one though (it was also 1975~ vintage). It also had an elaborate build guide with tons of illustrations, because evidently the "kit" in "Heathkit" is literal - sold as a kit! At least, before it got to me fully assembled.

[@frankowalker4662]

O.K. Two things.... 1) I love the way you have got 'chapters' on your YT vids, very clever. 2) Replace ALL the cap in that test/rejuvenator set and it will last another 50+ years.

[@dschult3]

I was incredibly impressed with the chapters as well! What a nice detail!

[@AiOinc1]

The capacitors in this device are probably fine - None of them are particularly critical and their values drifting won't cause many issues. Resistors are what you'll worry about for devices this old. They can start to drift or fail in other ways that would make the results inaccurate or could damage the tube you're testing. You don't *need* to replace all of them. Replacing all of the parts is not diagnostics and it's a waste of time and money if they work. If you used a device like this daily or wanted a display piece then yes you should probably replace all of them now.

[@tactileslut]

@@AiOinc1 Maybe it doesn't matter on an uncalibrated intermittent duty piece, but DC leakage can be happening at the operating voltage without it showing up on a low voltage meter.

[@adriansdigitalbasement]

I tested them all with my LCR meter and replaced the on that had failed. The rest mesure within spec (reistors and capacitors.) Yeah I only replace stuff that has failed... not stuff that "might fail" at some point in the future.

[@My_Op]

@@adriansdigitalbasement I'm delighted to read that. I have the same opinion and I'm a bycicle mechanic. (Digression: I wish I could send you some old computer stuff from Belgium so I could add some traditional candies!)

[@one_b]

This makes me think of my grandfather. He had incredible knowledge from a career in the Navy. He would have loved this video.

[@adriansdigitalbasement]

He probably would have had so much good information to share too. So much of this type of knowledge is lost.

[@tomcarlson3913]

As a vintage TV collector/restorer I can say: These old testers will have lower heater voltage with the heater connected than without. CRT heaters are not nearly as delicate as you think (except for some low current heaters some portable micro TVs)...Case in point there were devices called CRT brighteners common in the 40's-70's that would step up heater voltage by 40%, and the manual for my B&K 466 reccommends doing that as a first step...It is the gentlest form of rejuvination. CRTs that have sat for months to decades unused develop what TV collectors call "sleeping sickness". The cathode is made of a reactive substance that emitts electrons easily when heated. CRTs must be under HIGH near perfect vacuum inorder to function properly but there is always stray gas molecules floating around. There is usually a brown or black spot inside the glass aroung the electron gun called the getter that is a reactive metalic film designed to collect gas molecules... The cathode also acts as a getter, but regular use cleans the gas off of it....When it sits the gas that bonds to it builds up an insulative film that blocks emission....That film is the root cause of sleeping sickness. The safest way to wake up a sleeping CRT is to test it under normal parameters and if after an hour long emission test it does not wake up bump the heater to 1.4x-1.6x its rated voltage and check back every 5-15 minutes for a ~2 hour span...If that fails doing a rejuvination like you did is the next step. Doing a rejuvination is sometimes aided by at the same time as the button press gently taping the neck of the tube with a wooden dowel (be careful not to break the glass). There were various rejuve circuits from different makers common back then was to cahrge up a large cap and dis charge it across the cathode and a grid to create a brief spike in cathode current to blast the surface contamination off...Many testers elevate heater voltage during rejuvination. The emissive cathode coating is thin and will be blown off its metal substrate if too many rejuves occur or if too many hours are put on the CRT. Good life test is 3-11 seconds before the needle hits zero. All the lytics should be changed if you plan to use that tester regularly. Brighteners were usually step up transformers for the heater AC holtage (some also or exclusively did isolation to fix heater-cathode shorts). Most brighteners only worked on 60Hz AC because most sets that old used a 60Hz heater transformer. In the mid 70's-mid 80's TV/monitor makers switched from linear 60Hz power supplies (feed wall voltage into a transformer distribute it to loads and rectifiers that power everything) to 17KHz switch mode power supplies (rectify and filter line voltage use, use a transistor to create 17KHz AC by switching that on and off, use a 17KHz transformer to step it up then distribute and or rectify and distribute that to everything that needs power). Transformers don't like to opperate at frequencies substantially different than design so if you find a 60's vintage brightener installing that in your mac will cause damage. There were some 17KHz brighteners made but they are very rare.

[@WalnutSpice]

Aight as a 22 year old reading some of these, we really need to have an archived CRT info website. Just full of random stuff like this. Can't let this knowledge/ decades of experiences die or become simply impossible to find

[@tomcarlson3913]

@@WalnutSpice Videokarma.org is such a place. I'm only 6 years older than you and picked up much of what I know about TV repair in the last 15 years reading there (getting my bachelors in EE in the middle of that also helped).

[@cee128d]

And if nothing else it was a fun learning experience no matter how long it continues to work.

[@FyberOptic]

There's so much science and technology in tube displays, it's a real shame that we've reached a point where you see them sitting on the curb often nowadays.

[@Quickened1]

Its called progress... In their day, they were a marvel, but by today's standards, they are energy hogs and polluted boat anchors... Some things are best left behind, with a small remnant to remind us where we came from...

[@mrnmrn1]

Wow, when I recommended you under the previous video to rejuvenate it, I thought you will need someone's help who has a rejuvenator, I had no idea you already have one. Rejuvenation is usually a temporary fix, but there are exceptions. I guess this will have a long term effect. If not, try the high setting next time. Why I'm thinking it will last? In my opinion, this CRT was not tired, it had cathode poisoning. Because the way these Macs work with the black border around the picture, if this tube was used a lot, it would have a burn-in mark on the screen which resembles this black border, but I can't see any burn-in. Remember, the power supply was giving a low voltage on the machine in which this CRT was installed. This is one way to give a CRT cathode poisoning: run it on too low heater voltage for a long time. There are some other possible reasons, like slight gassiness, if that's the case, it will get poisoned again, it might need a getter re-firing with an induction heater. Good work!

[@electronicengineer]

I agree with your opinion of cathode poisoning being the underlying problem with this CRT. Reflashing the getter would most likely eliminate the cathode poisoning long term and add many years to the life of this CRT. Nice job Adrian!

[@HaveYouTriedGuillotines]

Doooo iiiit...~ As far as I'm aware, there aren't really good solutions for replacing the CRT in these old all-in-ones. Maybe there will be a good LCD solution in the long term, or something involving a full rehousing for the motherboards... But for now, it's better to try and get the CRT fully running again.

[@stevethepocket]

So a "tired" CRT is one that basically has burn-in all over instead of in a pattern?

[@mrnmrn1]

​@@stevethepocket No. Well, yes, if it has so many hours on it, the phosphor will degrade on the whole screen, but it affects the brightness just slightly. A CRT is being tired if the emitting material got worn off on the cathode(s), and it's no longer able to emit enough electrons. This will cause low brighness, and when you try to compensate for it by boosting up the contrast and brightness settings, the CRT will smear the high brightness parts of the picture, and becomes blurry. On some extreme cases, the high brigtness areas will turn to negative.

[@compwiz101]

Rather reminds me of why most nixie clock designs will have an "anti poisoning" mode where it will cycle through all of the numbers (even those not normally used) at full brightness to prevent this very issue.

[@IlBiggo]

"This thing is from the '60s so it's definitely really old." Me, a man from the '60s: T_T

[@adriansdigitalbasement]

Haha yeah I realized that came across wrong after I said it! Old for technology :-) Not humans hehe

[@marco_evertus]

Me, a man from the late ‘90s: yes you are

[@IlBiggo]

@@marco_evertus When this equipment was new I would have called you an old man .-P

[@KennethPlaysOfficial]

@@IlBiggo your as old as my grandpa

[@IlBiggo]

@@KennethPlaysOfficial Maybe I *am* your grandpa.

[@HermannR-o6h]

Hello Adrian. CRT rejuvenation is an analog process, that takes a little time. That means, the button should be pressed for at least 1 to 2 seconds in the low or medium settings (count "21 .. 22" while pressing the button). The definition of "briefly" as it says in the manual is vague at best, but the thing is one should not exceed about 5 seconds as that can make matters actually worse. Excellent video and my best wishes for 2024.

[@abc-ni9uw]

I was reading somewhere ( 3 years ago ) about a trinitron that needed rejuvenation In 1977 tv was only 6 years old but worked for another 30 years before it was junked

[@ramakrishnamishra8179]

Trinitrons are the best CRT TVs ever made!

[@abc-ni9uw]

@@ramakrishnamishra8179 that's why I have a huge collection of pvms and bvms

[@Naitrio]

@@abc-ni9uw Oh sweet i'd like to get a Sony PVM or BVM one day.

[@ramakrishnamishra8179]

@لای آسمووونی yes!! That is engineering!

[@ramakrishnamishra8179]

@@Naitrio yes they are great sd monitors!! Check out my channel where I hace content on them!

[@Ra-zor]

Remember using one of those back in the 90's to bring back to life hundreds (probably over a thousand thinking about it) poorly customer crt's over the years, and must have had about 30 different base plates in a big drawer in our lab. Most heaters ran at 6.3v. They worked quite well for about a year or so but then the crt would fade fast, but you could kick a tube several times before it was scrap. If you gave it a good blast you could see the rubbish being blown off the gun, see the needle kick and usually worked quite well.. The good old days! Oh and ALWAYS make user you fully discharge the tube or you will blow a hole in the phosphor on the tube lol

[@richardkelsch3640]

Remember USA power was 110-115 volts many decades ago. Now days it averages as 124 volts. So capacitors rated at close to voltage (as was typical back then) will blow, especially if they were already leaking. You need to completely recap and repair the tester before using it. I would also recommend using 500 volt caps instead of 450 volt. Be careful of higher capacitance ratings on old equipment. The capacitance rating was part of the design to "shoot" a pulse into the CRT. Making changing the capacitance completely changes the math in this circuit. Mr. Carlson's Lab is an excellent channel to help you with older equipment like this. I GUARANTEE you that those capacitors are extremely leaky (electrically leaky) and need to be replaced. Typical L/C meters do NOT test for leakage. A leaking capacitor can read fine in capacitance and even read fine with ESR, but can still be turning itself into a resistor (leaky). Replace all of those old caps.

[@mikehansell7156]

I'd like to make a couple of points: 1) A heater is not a filament. A heater is used to indirectly heat the cathode. A filament is a directly heated cathode 2) The raster is the grey (in this case) area displayed on the tube. The lines that are visible with extreme brightness are called retrace lines. 3) I think you'll find that the 6.3V heater supply is AC, not the 12V DC that is probably feeding the Mac tube. I the old days when tubes (or valves as we call them in Australia) were popular, there were devices that were basically a small transformer that could supply higher heater voltages to brighten picture tubes. These picture tubes lasted some number of years with the increased voltage. Many years ago

[@tekvax01]

I've seen people try to rejuvenate old CRT tubes, and completely render them useless in the process! It is a gambling crapshoot! if you blow the heater or short one of the grids, it is GAME OVER man! BUT, when they work, they really make a difference! I use to work for a post-production house and I repaired a bunch of Shibasoku 21-inch high res component monitors that used to cost $45 to $50 thousand dollars! We had a similar B&K tube rejuv/tester, and we repaired a bunch of old tubes with it, some even had shorts, etc... It either worked great or it killed the tubes dead, there wasn't much middle ground!

[@parrottm76262]

...a bad capacitor... Ha! Color me surprised! Love this video. It is like watching the 3rd Indiana Jones movie when Indy was winding his way through all the traps.

[@kirishima638]

Possibly your coolest video. Incredible.

[@Maoyon28]

When I saw the title I guessed that your just going to add 2-3 more volts on the filament, to my surprise there's that machine that you have that I never heard or read about at school. This has been educational for me, thank you.

[@batlin]

Have to say that was more exciting than I expected! Great work improvising the adapter!

[@gkcnalaka]

Im still using my own DIY rejubivanation kit .... it work really nice

[@ghettosteeve]

its generally reccomended you wait about 20 minutes for a tube to warm up before expecting an accurate picture in a mastering/color editing environment. you are supposed to run a white screen in that time for best results

[@cablecartman]

Very nicely done. Perseverance pays off!

[@ForgottenMachines]

Oh, but I DO love this video...first time I've seen one of these rejuvenators in action, nicely done! You've demystified a LOT here for me, even though you were learning on it yourself at the time, I followed right along with you...very helpful! Keep doin great stuff like this, Adrian!!!!

[@MurderMostFowl]

what an awesome goodwill find! Glad that it ended up in good hands instead of a dumpster

[@mymessylab]

Nice and helpful instrument. As tv rapairman I’ve used many times successfully. Good idea to get it👍🤗

[@nialldaly7108]

I worked in a TV Repair shop back in the early 80's in Kerry, Ireland and that used be done with the rental TV's that were out from the shop if the tube was "Lo". It worked for a few months to a year before a new tube was required or may even get another Boost. That is what we called it. "Boosting the tube ". It worked OK but not a permanent solution, but a few months to a year was not that bad.

[@stevejones8665]

Way back when I was 5 years old in the good old days of black and white all valve TV,s I learnt and watched my Dad fixing TV,s and whenever the Cathode Ray Tubes emissions where getting low or the picture was out of Focus and very silvery looking all over, he used to rejuvenate them without even having the Test unit you have. Usually what causes the low emission is a short from the heater to the cathode which you can't read with a test meter. How he fixed almost every one was to get a piece of coax and touch one end onto the disconnected CRTs cathode pin and the other end onto the EHT output from a line transformer usually around 12 to 15 Thousand Volts which blasted the carbon short away , he would then do the same to the heater pins. If this didn't work well enough we would fit an isolation transformer to supply just the 6.3 or 12.6 volt heater only, this effectively removed the short between Cathode and heaters allowing full emissions. We did this to many TV,s because new or reconditioned CRT,s where very expensive at the time. There where also many TV tube recondioning factories who replaced the Electron Gun Assembly including the Tube Neck for a lot less than a new tube (crt). If you overdrive the CRT by increasing the voltage then the CRT will start emitting dangerous levels of XRays from the front which is never a good idea. All CRT,s emit small amounts of XRays. I did go on to become an Electrical and Electronics engineer.

[@theradiomechanic9625]

Adrian, go to e-bay and search for "picture tube booster" or "picture tube brightener". These are small transformers that go in line with the picture tube connector. ( it will be obvious when you see the photos of them ). They boost the filament voltage by about 2 volts. While there is a danger of the filament life being shortened, when all else fails they will give you some additional life from a "useless" tube. These were very popular "back in the day". There is presently a lot of 5 selling for $9.99 and one of them appears to have the correct socket/plug combination.

[@saxonian]

Hi Adrian, I've seen some videos from a German TV technician explaining all the rejuvenating stuff. Here is what I've learned from that videos. The cause of the tube getting darker is some oxidation at the surface of the cathode that builds up over time. The rejuvenation is the process of removing this layer. If you turn down the lights you might even see the dirt flying of the cathode and being burned away. So what you did was basically correct. In the video he was also talking about the different tubes and the different voltages of the different color and much more. This is kind of a science of its own. Btw he was not to hesitate about pushing the button ;-) Starting at low and tying to burn away the stuff a few times. If it wasn't enough he used medium. High seem to be really aggressive and the tube might not take it well. But if it's not working with medium the tube is almost toast anyways.

[@maxpowers2168]

With content like this no wonder is my favorite tech channel

[@seshpenguin]

Wow, thats an interesting piece kit! Your right, this CRT is the perfect one to test on, it was going to be thrown out so there is nothing to lose. And hey, you may have a working CRT now!

[@Aruneh]

Very interesting to see "ancient" tech like this being used and not just sitting in a museum!

[@Sheevlord]

It would be cool to know if this lasts if you keep using it. Maybe make a follow-up video several months later comparing the performance. Also, it would probably be a good idea to replace the rest of the capacitors just in case. It doesn't matter that they seem to be working now - they are over 50 years old at this point, so they probably won't last much longer

[@oldestgamer]

words of wisdom

[@Fly0High]

@@oldestgamer If your a Mr Carlson's Lad regular, you'll know those caps are leaky.

[@classiccomputers6211]

They're dry electrolytics, they are probably fine. I've found plenty in old equipment that still test new and I have not yet had any fail on me in service.

[@AiOinc1]

For equipment you care about keeping for a long time, yes you should probably replace all of the capacitors and the resistors right now to prevent future problems. Old resistors fail very often in these types of devices as well as the capacitors. But that's not diagnostics, that's full on restoration at that point. CRT restore/rejuvinate is pretty widely known in the television community to be a gimmick. It's just a band aid to give you enough life to get the customer a working television while the shop orders or rebuilds another tube for them. It's similar to a CRT brightener - You're not supposed to keep using it for so long after.

[@Sheevlord]

@@classiccomputers6211 Well, given that one of them failed right in the video I'd say that replacing the rest is a good idea.

[@GadgetUK164]

Excellent video Adrian! I've been hoping to see a video on this subject for a while! I remember when I was in the trade my boss had a DIY rig that he had built himself, it comprissed of a light bulb (presumed to limit current) and a transformer. I think he basically powered the heater and drove some high voltage through each of the guns. I saw him use it on colour monitors back then and I was amazed how much brigher they were afterwards.

[@kuro68000]

Didn't it say wait 15 seconds before doing medium, I guess to let the cap charge? Anyway interesting result!

[@zaprodk]

It's to let the filament get to a stable temperature

[@oldofftime]

Since you are asking for comments and suggestions. It's good, enjoyable, thank you :-)

[@lorenzoporciani]

Would be nice if you got someone to reverse engineer it! Having a modern open source crt tester would be a saving grace on those aging tubes! Also, ask a certain Mr Carlson to see if you have to swap out those caps, because they seem those old cardboard ones!

[@henriqueolifiers6400]

That. Would love a 'rejuvenator' like this around!

[@1959Berre]

The replacement of the electron gun on a tired CRT used to be done by very skilled technicians. That art has been lost in the mist of time, along with the equipment to do the job.

[@IrishvintageTVRadio]

Always worth a shot with a tube that's going in the bin anyway. Always a last resort though. Great video and a cool BK.

[@JamesPotts]

You snagged a rejuvenator at a thrift shop?!?!?!

[@laurensa.1803]

You stumble upon the weirdest things at thrift shops. Is this an unfamiliar experience to you?

[@AiOinc1]

Tube testers and brighteners are extremely common, they were service grade equipment and lots of people had them.

[@Damaniel3]

I hit up Portland area thrift shops all the time and don't find anything nearly as cool (probably because Adrian's picking it all up).

[@iamdarkyoshi]

One of my friends got a 90's tester/rejuvenator for 15 bucks, it's 400$+ on ebay right now If you go thrifting, go everywhere and go often

[@mrnmrn1]

Yep, I wish we had thrift shops like this here in Hungary, and I wish CRT and tube testers to be this common like in the US. In here, they were never a common thing. Only the government/military had tube testers, and even they had just a few. Some of the biggest post offices had tube testers (for maintenance of the telecom systems), where they also tested your tubes for a fee. CRT testers/rejuvenators started to occur about in the mid '80s, but they were very expensive, so only a few repair shops bought them. Then in the early '90s, someone probably here in Hungary copied a Spanish Promax RT-501B CRT tester/rejuvenator, and sold them as "Sam's CRT regenerator" m.blog.hu/tu/tubemania/image/img_2435.JPEG . There are not much of these around, it is very difficult to get one second hand, and also quite expensive, so I will probably build one, the schematics are available.

[@unaphiliated5090]

I had some luck with these back in the day, but those old monochrome tubes could be replaced with new ones fairly cheaply. Unless you bought from Apple of course, their prices were way higher. The trick was to find the right replacement based on specifications. Most picture tubes came from 2 or 3 manufacturers, and they had very detailed catalogues (this was pre-Internet). Got to be careful to discharge them before you work on them, the tube itself is a large capacitor that can store it’s 20 kilovolts for a couple of weeks.

[@anumeon]

My heart honestly skipped a beat when i saw that thing.. Ohh,, so cool

[@ksaspectre]

Wow, I can't believe how much of an improvement that was. And it's awesome that it got saved from e-waste.

[@jagardina]

I bet Mr. Carlson from Mr. Carlson's lab channel would have one of those or something that would work. He might also guide you in the best way to work with CRT tech. He's extremely good with older tube tech. Great channel (at 1.5x).

[@adriansdigitalbasement]

Heh I've watched his channel a bunch -- and yes, I also use 1.5x :-)

[@jagardina]

What does the manual say about the lo-m-h? What does it change?

[@jagardina]

@@adriansdigitalbasement Watching the end bit, I'd replace all those electrolytics. They just don't last. And possibly some other components. A cap can test acceptable for capacitance but could also be acting as a resistor. In a tube circuit, caps that can conduct DC can wreak havoc on the tubes. They get driven way to hard and it will burn them out. I don't know enough to say about the resistors but those you should be able to get a reading to see if any are bad.

[@jagardina]

@@adriansdigitalbasement His latest ROBOT HEAD he does a great deal of work on a radio built similarly to your tube tester. Point to point. Bad caps, etc.. But he does have a lot of those. It's long of course.

[@XnoobSteve]

This was amazing, thank you. I can only imagine the satisfaction you got from this

[@hadireg]

Great stuff!! Thanks for explaining how that process goes! :) pretty shocky indeed! :) 👍

[@delorean00]

Great job!! As for how long it will last, we have lots of CRTs in TVs that are rejuvenated that have hundreds of hours of use and still look great. It really comes down to the age of the CRT, how dead it was when you started, along with a bit of luck. Also in the beginning when you said it would get brighter the longer it ran before your rejuvenated, that is really common with CRTs, some will warm up after not being used a long time and never dim back out. I suggest if you have a dim CRT on a machine that works, let it run for a few hours a day for a couple days and see if it gets better and stays that way. Sometimes the CRT just goes to sleep when they sit.

[@carlosbragatto]

Absolutely gobsmacked how well this turned out. Great video!

[@ovalwingnut]

I liked "and" approved of this video! Very COoL. Enjoyed it immensely 👍😎

[@PaulinesPastimes]

This is the first time I have seen an objective test of this function and it is fascinating. You didn't have any expectation bias and just gave it a go. It's a great result. Cheers

[@heathm]

I picked up a Sencore CR70 off ebay several years ago. It came in handy in testing and restoring monitors in a couple arcade machines. I guess it's suppose to burn off carbon build up within the CRT to clean off that buildup. But at the cost of shortening the life of the electron gun. But of course if it is looking bad and your going to junk the monitor. Might as well give it a go. As maybe a side note, The manual restore procedure on mine says to let the heater warm for 30 secs before hitting the restore/rejuvenate button and to never go over 15 seconds of holding the rejuve button. Not sure if that helps with the B/K operation. Any way, keep up the great work! I enjoy the videos that you have made available. Keep it going!

[@bigpapab]

That was really cool. I did not know of that device. Excellent video on how to bring back old tech, with old tech to fix it. Keep it up my friend!

[@video99couk]

I built my own CRT rejuvinator from plans in the UK publication Television magazine. It brought back many a TV and old computer monitor to get some more life out of them for their owners. Not used it in years now but it's still in one piece, maybe I'll get a tired CRT in one day and get to do a KZbin video like this. Nice find to get one of these in the thrift store, though it's not very pretty inside.

[@flemmingchristiansen2462]

Great work bringing the screen back life. There are probably many people who envy you. You probably might want to replace the capacitors in your CRT Tester. I think i saw an old "roundy" resistor, they dont handle moisture so well I'm no expert but even though the capacitance and ESR measure right, the can be leaking badly. "Mr Carlson's Lab" have some good tutorials on old components. Great piece of equipment you found there.

[@lauram5905]

I wouldn't mind seeing a proper restoration on that tube tester if you have the time for it, rewiring it and having a standard base that you could plug all those sockets into would be neat. Maybe breaking out the sockets into a common (high voltage) connector (ATX molex?) might make it a bit friendlier to use

[@lauram5905]

Also you probably already know this, but Mr Carlson's Lab and Shango066 are both excellent resources on field equipment like that. Nice find!

[@Sheevlord]

@@lauram5905 Mr Carlson would also say that those old capacitors should go even if they seem to be fine. He always replaces old electrolytics.

[@benbaselet2026]

@@Sheevlord And I do think he's right. With the cost of those parts nowadays you'd be crazy to test them 6 different ways just to save $2 a piece to run them a little longer and possibly blow a bunch of other kit when they do go with a bang. Really easy to replace too with that old point to point wiring.

[@lauram5905]

@@Sheevlord Shango tends to make an important point depending on what he's working on that some pre-power on troubleshooting should be done before a wholesale recap in case that ends up masking an issue but yeah, checking voltages. physical inspection and calibration prior to connecting it to anything would have been my first thought. He definitely had the right idea making sure he knew what pinouts he'd be dealing with though. Wonder how many people have blown up tubes just socketing them without checking

[@garthhowe297]

That was amazing Adrian.Thanks for pursuing trying to fix this "lost cause" CRT. The results were way better than I expected.

[@enzoperruccio]

Now it's just a matter of how long the effect will last before the crt goes dim again!

[@dan_loup]

We will know the how long now.

[@enzoperruccio]

@ungratefulmetalpansy Yeah I've seen some videos. The technique is called crt rebuilding, and it's almost a form of art because of the amount of time and skill it requires. Either way, the end result was always a like-new picture tube.

[@TofuInc]

I used to work on arcade games around 10 years ago. We had a "tv guy" who would "shoot" the crts. The results were impressive what he could accomplish. If its the fist time on a crt it can last for years. He has since retired and close up his shop. I moved on from that job but learned a lot from it.

[@xyzconceptsYT]

Oh wow, this reminds me when I used to re-gun CRT's in the mid-'90s. Fascinating process. Oh, and the post oven and vac down spot-knocking process were always fun and firing the getters with a high powered RF induction coil.

[@arfink]

I've been really interested in the re-gun process for some time now, but there's almost no information out there about how it works, what the process is like, or what equipment is used.

[@VladoT]

Its great that you took my advice from the previous video and tried CRT rejuvenation, now you need to buy or build in-circuit ESR meter for you to be able to test caps without removing them from the boards.

[@adriansdigitalbasement]

Oh I show my DE-5000 which I bought which allows me to test in circuit. Also a secret -- I made this video on May 8 -- so it was luck it seemed to be a response to comments. :-)

[@frugalprepper]

This is a really cool video. When I first started working as a tech in the 1992 we had one of these on the shelf in the back room. We use to use it on ADDS dumb terminals that the screens got too dim on. I don't think there was ever a time that they came back with a screen to dim again in the 4 or 5 years we did it. Eventually all the customers just left the dumb terminals behind and put in PC's with ProComm though, so they were already well on their way out before I started working there. Great video.

[@speedbuggy16v]

nice find, I picked one up at a yard sale a while back.

[@SarahWattCA]

Someone on a forum I read found one of these at a thrift store recently and I was curious about how it worked but I couldn't find any information, so thanks for demonstrating

[@eDoc2020]

Great to see how this came out! I have an old portable TV from 1982 with a dim picture I might want to fix up. And in other news, the shorted capacitor in the tester could've been worse. I was working on an old tube intercom and a capacitor failed shorted between the ac input and the metal case. Fortunately I did a quick safety inspection of the internals before plugging it in. I highly recommend anyone dealing with old equipment in unknown condition perform a similar check as well.

[@QuaaludeCharlie]

I have 3 TV testers , I have never used them yet , but I am happy I found them in my city . I hope to get a chance to use the rejuvenator functions and well any result as good as this will be a Win :) QC

[@ArixZajicek]

Whoa, I've never seen the segment feature on KZbin before, neat!

[@anotheruser9876]

Saw a CRT tester/rejuvinator at Value Village today (CDN$29 IIRC). Couldn't help to think about this episode.

[@greendryerlint]

Cool video. You should zero the analog meter with the screw on its face--it might be a little more accurate. I've always wanted to see one of these used, and love it when ancient test gear can still be relevant. I'm not nearly old enough to know this, but I remember there were also kits you could install for ailing CRTs that would boost the heater voltage on a weak tube to get a bit more emission.

[@borayurt66]

Electrolytic capacitors age and die as you know too. What I prefer in my restorations is to change them all, regardless of what they show on a capacitor leakage tester or an ESR meter like yours. (Good instrument by the way, congrats on the choice) Any old capacitor that is OK today and you decide to leave on the board, will be the source of a new problem in near future. I love the "rejuvenator" what a great find. Very very lucky guy you are, most probably it will never do any good, but it looks fantastic. I was about to say that there must be a bunch of dead capacitors in the CRT tester too, but you found that out. :-)

[@lorenbufanu1639]

there was 2 way of fixing a screen in my town at the local repair guy: 1 way, was to increase the filament voltage, by wraping a piece of wire on the high voltage transformer, or, second one, the risky one, was to discharge a capacitor on the heater element. both worked most of the time...

[@spishco]

Bringing back memories of Apple repair training from the 90's. Careful of that flyback voltage buddy! :)

[@askhowiknow5527]

I can’t wrap my head around how not a single one of the wires on that adapter has continuity

[@SeanBZA]

Heavy oxide layer on the pins will do that, and perhaps the potting has shrunk with time and snapped off the internal wiring as well.

[@mrnmrn1]

Possibly they used some agressive, corrosive (acidic) flux to solder the wires. I've seen this before with figure-8 type power cables.

[@alexandrecouture2462]

This is so cool! I have never seen such a machine before, or even less know that it exists!

[@finkelmana]

Have you checked out Mr Carlson's Lab on KZbin? He repairs and used vintage tube test equipment to repair other vintage tube test equipment. If you had any questions about testers or anything tube related, he is the guy to talk to.

[@M0UAW_IO83]

We had one of the later 467 models with a bunch of adapters, had good results with colour tubes that got quite a bit of extra useful life out of them but monochrome ones were rubbish, you'd get a few weeks, maybe a month or two of brighter picture but it'd fade real quickly. We also found the more you rejuvenate the shorter the life. Handy trick for a poor emission tube is to boost the heater voltage, an extra 0.5-1V can make quite a difference to emissions, if heater votlage is line derived then an extra winding or two on the ferrite of the Line output transformer in series with the heaters might just do the trick.

[@johncarnege]

The sparks are good. They are "burning" the corrosion inside the electron gun. You can also hit it (gently) with a screwdriver (with the plastic side) and pieces will fall inside the tube and they will spark. It made my Hitachi tube from 40% to around 80%.

[@apl175]

This was one of the most amusing, quirky, and interesting of the "Digital Basement" series.

[@BersekViking]

We used equipment like this on color TVs in the late 70s to early 80s. 8 out of 10 tubes got longterm better. 1 of 10 faded the next day and the last 1 of 10 had no change. Newer tubes (inline type) had no or little change.

[@gizcommusic4596]

This doodad is amazing. It really bothers me how many service tools have been forgotten; let alone the principles they operate upon. Great video, man! Not joking, you need to send this to Me. Carlson to tear down in his lab. He would also be able to give a full description of the "Rejuvenate" function and just what it's really doing in there. Maybe even get some pointers for your audience on reverse engineering this thing with mossfets and a PC power supply. Keep doing the Good work, and sharing your valuable accumulated knowledge and problem solving strategy with all of us. You are doing far more good than you realize. K

[@smallmoneysalvia]

That’s an incredible change! Wow.

[@RavenWolfRetroTech]

I's love to see how this does down the road. Awesome video!

[@Wenlocktvdx]

The things I’ve found at thrift stores, vintage radios, Speak n Spell, gameboys, NES, games for SNES and N64, DSI XL, DS games, Megadrive/Genesis games, GameCube games, Wii, Wii 25th Anniversary of Super Mario Bros (red). Wii motes, Wiimotion adaptors, Wii games. There would have been a “universal adaptor” which is a cable with clips instead of a socket. You can attach the clips to the appropriate pins which is great for any crt that isn’t covered.

[@Megatog615]

That's such a cool old device. I wonder if someone could restore the box? I think the electronic component deserves a new housing.

[@WarpRadio]

I have used a B/K CRT rejuvenater back in the 80s I used the later model which did the steps automatically.. what it basically did (describing the automatic process) was to "tap" the button while removing the heater voltage and allowing the cathode to slowly cool this would cause a slight ARC across the cathode and "blow away" any oxide on the cathode surface.. thus "rejuvenating" the CRT; the process was ALMOST idiot-proof, however, one can still "over do" the process and end up destroying the surface coating on the cathode.. I say you can try this on "high" and see if also flipping the life check switch (which just removes the heater voltage) and see if it can effectively "bring it back to factory" your CRT there is NEW-in comparison to some of the CRTs back in the 50s that I have brought back to life! I think you'll have good results... (again, I used the later version of that tester which had an automatic rejuv function...) I hope this helps! heres a quick link to some images of the unit: images.app.goo.gl/QVUzi3H46nJs3KEo7

[@bobbybiggs4348]

Definitely a good idea to replace all those old caps. But 100% thumbs up for the video! I never knew equipment like that existed

[@christianclark1354]

I remember seeing one of these things being used in the mid 90s on my parents tiny Toshiba CRT TV. Never knew what it was called until now. Thanks!

[@Maisonier]

Amazing video! I thought that could never work.

[@robintst]

Such an interesting intermingling of old tech with even older tech.