(Classic) Tektronix 502A scope repair / restoration - Page 1
Forum section: electronics / repair

author: Vince
author_rank: Super Contributor
timestamp: November 18, 2018, 12:20:28 am
content: Hi there,Now that I have finally completed the restoration of my first tube scope, that little Tektronix 317 (https://www.eevblog.com/forum/repair/vintage-tektronix-317-repair-and-restoration/) first tube anything really, which was a rough road, knowing nothing about vintage scopes or tubes at large... it's now time to get my hands on another one of these beasts !Yes, when I bought the 317 a year ago, I "promised" myself it would be my first and last piece of tube equipment.. because they are large and heavy, mostly.Problem is : once restored, my 317 is such a joy to look at, and play with... that now all I can think of, is getting more and more of these old Tek scopes ! I got infected by the virus, it's in my blood now, too late to go back !So, just in the recent weeks / months, I managed to source a few more of these : 3 more 317, so that's now 4 of them . Then a cute little 310A, then my first my '"big" 500 series scope : a 531A... normally you can't buy these models because they exceed the weight and size limits of transporters, not by much, but still.But luckily this 531A was "reasonably" close to me (under 100 miles away), so I could, just about, consider driving to go pick it up myself... so I did.Then I bought a 502, then a 502A, then 515A which is on its way currently, and I am in contact with a seller for yet another 502A !And I don't plan on stopping there... For 50 to 75 Euros a piece, a modest spending, you get quite a nice piece of engineering, a beauty to look at, a piece of history, and a good few hours of fun troubleshooting and fixing the stuff, then restoring it, then a lot of satisfaction playing with it, once it's all shiny and working like a champ. A lot of satisfaction indeed in many regards, and for very little money ! That's why I don't think I will stop buying themAnyway. They will eventually all get fixed and restored, at some point. For my second restoration, I will lay my hands on.... on.... on the 502A !You can read about this scope (502 and 502A) on Tekwiki, including service manuals and pics :http://w140.com/tekwiki/wiki/502Basically it's a special purpose scope : monolithic, high-sensitivity (0.1mV) / low bandwidth (1MHz max), dual channel, differential inputs, and a dual beam CRT, and an XY mode as well ! So not your general purpose 500 scope indeed. That's mostly what attracted me to this scope, along with its looks.. I quite like this scope.Actually this is a scope I bought for spares only (or so I thought ! ) to help me restore the 502 (non 'A'). The 502 was tested good by the seller, and scope had a good life, a nice scope all around.The 502A however, had "donor unit" written all over it : sold "as is", untested, seller knew nothing about the scope, didn't even have a power cord to test it anyway, looked real crusty on the outside, and blatant signs of physical damage at the rear of the left side panel of the cabinet. Pictures taken on a concrete floor outside... looked like it had sat rusting in some hangar or barn for the past 30 years...Really, I bought this scope purely for parts to assist me in restoring the 502, no other thoughts in my mind when I posted my cheque to the seller...Then when I received the scope, I was comforted in my plans, as I discovered that the physical damage was even much worse than what I noticed on the seller's picture : as you can see, there is severe damage to the rear top left corner of the cabinet !!!Looks like the poor scope fell from the bench on its arse, this corner of the cabinet took most of the impact, and the damaged side panel now looks looks like the least of the damage, in comparison with the state of the chassis/framework...The air filter frame/holder has a big dent in it as well. Also, there was a problem with the CRT : even without opening the scope, you could figure there was something wrong with it : looking at the front of the CRT, you could see that the face of the CRT was not "right behind" the graticule... it was like half an inch further away, like it retracted or something... not good ! Then I opened the cabinet to look at the CRT, and well yes, the CRT took a hit as well indeed : the area around its neck looked like a total mess : the nylon clamp mechanism that's supposed to hold the neck firmly in place, was all over the shop, shattered. Also, there was lots of unidentified debris all around the neck (see pics),... I thought oh no, the neck must have broken/snapped during the impact, the CRT is dead, for sure ! Still, when I wiggled the connector at the back of the CRT, it seemed like it was still firmly attached to the CRT, so maybe the neck was not broken after all.... just maybe.Add to that, that the seller doesn't understand what "packaging" means... he got confused with the word "wrapping" I think ! There was ZERO packing material in the box ! The scope was literally shoe horned into a box that happened to be just the right size ! So this combined with the initial condition of the scope... doesn't make for high hopes, doesn't it...Still, I decided to power the scope up anyway, just to confirm that the CRT was dead and the scope a write off, and I would not have been surprised if the scope smoked, caught fire or exploded at me. Really, I couldn't possibly think of a worse scope, so I had to expect the worst at power up, in return, logically, eh...Powered it up, with the calibrator signal feeding both inputs (set to single ended for convenience).... fan comes on, rattling... and no trace on the CRT... "of course". No trace whether I set the scope to XY mode, or "normal"/swept mode. There is a switch accessible through an opening in the right side panel, that lets you select either mode of operation.However, fiddling with that switch back and forth, I eventually noticed that if I left the switch in between its two stable positions, in mid air so to speak, then I would get something on the screen, somehow !A couple dots, whose exact shape and focus and position would vary in funny and unexpected ways, depending how I fiddled with the various controls...WOW ! So that meant that the CRT was not dead, at least not completely ! It meant at the least that the neck was not broken.. .for if it had been, there would be no vacuum anymore in the CRT and it would not work. It also means that the two cathodes/guns work, since they can produce enough electrons to shoot a spot on the screen... Also means that the CRT HV is working (though there is no PDA on this scope, unnecessary given its very low bandwidth).Still, it was acting very funny, and the dots were immobile. so there could still well be internal damage to the CRT electrodes, which would explain the bizarre behavior.Then I had a look around all the tubes, and as I marveled at how nice all these glowing tubes looked, one of these numerous tubes caught my attention : "HEY, looks like this one is NOT glowing, it's completely dark " That can't be right... no matter what happens, when the scope is powered up, the filaments of all the tubes are powered in unison, so all tubes should glow !The one faulty tube was in the horizontal section of the scope, close to the CRT HV section (see pic). Hmm.... a faulty tube in that area would possibly keep sweep from working, hence no trace ! So the CRT maybe is not at fault here...That's getting exciting, we are on to something !!Looked that tube up in the schematic. It's V324, it's the upper tube in the horizontal amplifier : gets the ramping voltage in, and is supposed to amplify it to drive the horizontal deflection plates. Sure enough, sweep can't work without this tube ! It was a 6AU6 tube... by some miracle I DID have some of these tubes, the only ones I have, because I bought a few during the restoration of the 317 scope. It had a problem in the vertical amplifier, and it used a 6AU6 as well. Lucky me !!!So I popped a new 6AU6 in the 502A, crossing fingers.... and hey presto, scope now WORKS !!!!The square wave from the calibrator output, displays just fine on both channels, nice traces, sharp and bright, stable, like I bought one !See pics below.Couldn't believe it ! A scope in this bad a condition, severe physical damage/shock, a CRT that took a big hit, and shipped with zero packing material..... was somehow still perfectly functional, just had a bad tube ?! Really ?!So, once I got two nice traces on the screen, of course I played a bit with all the controls to get a quick idea of what works and doesn't... and well, everything works ! Triggering works fine, on both channels, including external triggering input. Time base works. Time base magnification knob also works (x2 up to x20). Horizontal and vertical position knobs work. "beam finder" buttons work. Vertical amplifiers/attenuators work, focus and intensity controls work...After a good hour playing with it, the traces were still bright and sharp and stable, which means that the CRT HV section is also very healthy : doesn't drop like it often does due to bad caps and / or leaky HV transformer ! The HV is rock solid !!This scope is a winner, it's back from the dead, can't believe it !!!So... there is now NO WAY I am using this scope for parts !! How could one resort to taking apart a scope that works just fine !!! With all the damage that this scope suffered, it's amazing that it's still in this good a working condition !! This scope clearly WANTS TO LIVE !! And I am not going to be the one sentencing it to death !So, yes... I now fully intend to restore this scope ! The big damage to the chassis can be sorted I think. The rear panel can be removed from the chassis, just a few screws I believe. Then it will be possible to work on it, and hopefully bend it back into shape. Then repaint the panel, and that will do itHowever this will need to wait until my garage/workshop is built... in a year or two maybe, not more I hope. I am also not starting the cosmetic side of the restoration just now either, because I will soon be moving home, so I am trying to tidy things up in the lab, rather than covering the bench with a scope in a million bits every where... However I can do the electrical diagnosis, and trouble-shooting, as this doesn't require to take the scope apart...So, once the decision had been made to rescue/restore this scope, I played with it again, for a couple hours, for a more detailed/thorough test drive, taking notes and measurements. Yes, work has officially begun on this scope... hence I decided it was time to create a topic for it, so here I am again !As I said, the scope basically works, no real show stopper. So I will only list the things that don't work, or need some attention :HORIZONTAL- Sweep length :As can been seen on the pics, the trace(s) don't span the entire width of the screen, far from that. They span about 7.2 DIV.Manual says it should span 10.6 DIV. I tried adjusting that with the appropriate calibration pot, to no available : I can make it much shorter/narrower, but I can't make it any wider. So clearly there is something wrong there. The sweep length cal pot is located in the " Time Base Generator" schematic page, so will look into that...I assume the ramping voltage doesn't reach the amplitude it's supposed to.- Sweep calibration :It's way, way off ! When I tried to measure the period of the 1kHz calibrator signal, I was in for a surprise ! LOL The calibrator is not far off its 1kHz target frequency, at about 1083Hz. So that's a period of 923us . What do I measure on the screen ? almost half that : 540us ! LOLAgain, I fiddled with the corresponding Cal pot, and the best it could manage, when turned fully CW, is 620us, which is logical as it's meant for fine tuning only of course... no way it was going to get me from 540 to 923us ...So here again, there is something wrong. I doubt the precision timing caps in the time base, would be so far off. So most likely it's again a problem in the horizontal amplifier, where we just replaced a tube to get the scope working. Maybe the matching/symmetrical tube of that stage is weak, typical, or just as typical, some carbon composition resistor that drifted far away into a distant galaxy ! LOLAnyway, these two problems don't worry me that much, shouldn't be too difficult to trouble-shoot I think...VERTICAL- The vertical position knob for the lower beam, is not feeling too well : when you turn it CCW, you can make the trace go waaay off screen, downwards. However when you turn the knob CW to shift the trace upwards, you often can't even get it off screen completely (depending on the signal amplitude of course). So there is an imbalance there, behavior is not symmetrical.Again not too worried : had the same issue on my 317, and others had it as well.. looks like a typical problem. Issue was a weak tube in the vertical amplifier. So again will be swapping 6AU6's LOL ! I am glad I bought a few of them back when I was fixing the 317, they are quite handy now !- (calibrated) Gain : slight mismatch between the two channels : when I feed the calibrator signal to both channels, and try to superimpose both traces, then one is slightly taller than the other, but only by a small division, for a 5 DIV trace on the screen. So no worries there, it's the kind of minor variation that will get ironed out once the scope is restored and I go calibrate the whole thing.- "DC Balance" control (one for each channel) : looks like the pots have given up the ghost ! It's a regular single turn pot, not a multi-turn pot, yet I can sense no stop in them... I can turn them freely 360°, round and round and round !They still do their job, mind you !So since they are not of the sealed type, I should have no problem opening them up to see if it's fixable. It not, will replace them. New ones might not have the exact same shape and fitting, as there are so many variations possible, sadly. But still, new one I can open/dismantle as well, take its guts and stuff them into the body of the old pots ! Make a good working pot out of the two...So this issue is not worrying me all that much either.- Frequency compensation (I think ?! ) : if I look real closely at the leading edge of the calibrator signal, I can see that the upper beam/channel displays a tiny bit of "overshoot", juuuust a hair, whereas the lower beam on the contrary, displays a tiny bit of undershoot/damping, corner is ever so slightly rounded off. So I might be able to correct this during the final calibration, will try anyway !MISCELLANEOUS- Cooling fan : starts on the button and blows healthily, and minimal axial play.. however for some reason it rattles ! At first I thought the blades were hitting the air filter mesh/grill... but no, they aren't. The noise does indeed emanate from the motor itself, somehow !Here it is :The motor is also very rusty, not very good looking eh... but I shall take care of that in the final stages of the restoration. For now it's about fixing it from a functional point of view, ie get rid of that rattling...- mains/power socket : somehow it's missing the earth pin ! However it's not due to physical damage. Looking up close, the socket is 100% free of damage. The earth pin looks like it's designed to screw into the chassis, through the socket. And it's just not there. Why someone would remove the earth pin, I am not quite sure... so he could make floating measurements perhaps ?... but this scope precisely has differential inputs, come on !- Scale illumination : doesn't quite work --> one of the two light bulbs is kaput...CONCLUSIONWell that's it for this introductory post, you know as much as I do about this scope nowSo I now know what needs to be done on this scope. First fix the electrical issues, then once I am moved into the new house and lab is operational again, will work on the cosmetic side of things, and minor refurbishing. Then much later once the garage is built and I can do some mechanical work, I will look into straightening the rear panel, repairing the chassis damage. But that will take a year at least (money doesn't grow on trees just yet... ), so in the meantime I will start work on all my other Tek scopes of course !A few pics and then off to bed...Not gonna all fit in the present message so will have to spread them over several posts.First some pics of the exterior, and then panels off, of the inside, all 4 sides, to get a good look under its skin, and at the same time see just how crusty and dusty it is...Then pics of the physical damageThen pics of the trouble-shooting / repair.

author: Vince
author_rank: Super Contributor
timestamp: November 18, 2018, 12:34:29 am
content: Pics of the dusty interior now... top, right and left.

author: Vince
author_rank: Super Contributor
timestamp: November 18, 2018, 12:42:04 am
content: Now the bottom of the scope, therefore not dusty for a change ! Quite busy/crowded under there actually...

author: Vince
author_rank: Super Contributor
timestamp: November 18, 2018, 12:46:23 am
content: And ending with pics of the physical damage : left panel, chassis corner, air filter cover/holder, CRT neck.

author: tautech
author_rank: Super Contributor
timestamp: November 18, 2018, 12:55:59 am
content: Nice one Vince.Subbed.........as always to another of your great repair write ups !

author: med6753
author_rank: Super Contributor
timestamp: November 18, 2018, 01:09:05 am
content: There's a 502 for sale on my local Craigslist but the clown wants $200 USD and he says it's half the price of the collector's market. He's definitely smoking something funny and I wish him good luck. At best it's worth $75 - $100 USD if working and I'd snap it up if I could get it at that price.

author: Vince
author_rank: Super Contributor
timestamp: November 18, 2018, 03:14:57 am
content: Quote from: tautech on November 18, 2018, 12:55:59 amThanks Tautech, here is hoping I won't disappoint !Oh, just realized I forgot to post the last round of pics : the trouble-shooting, and scope coming back to life.. in short I forgot the most important then !Here it is.I will spend 30 minutes to edit / proof read my post, I am sure as always that I will find 2 or 3 dozen typos. Should be cleaner and easier to read afterwards...

author: Vince
author_rank: Super Contributor
timestamp: November 18, 2018, 03:50:41 am
content: Quote from: med6753 on November 18, 2018, 01:09:05 amYeah a few weeks ago I checked Ebay USA for 502/502A, just out of curiosity. There were 3 or 4 for sale IIRC. some had silly price tags in the order of magnitude that you mention !Here in Frog land in our equivalent of " Craig List ", it's filled with way over priced junk that's sold "as is" with just a crappy dark pic and barely a couple words of description. I don't understand people...But somehow, the old tube Tek scopes are still very reasonably priced in comparison ! Might not last so I prefer to get them while I can still afford them...They usually go for 50 to 75 Euros. A bit below 50 for the real cheap ones, a bit above 75 for the better ones. Of course you get the occasional one with a silly price tag, like a few days ago there was a guy advertising a 555 for 450 Euros or something, if I recall correctly ! Looks like he already sold it, as I can't seem to find his ad any longer ! But that's not the majority of sellers thank God !Not too long ago I recall another 555 complete with its power supply and cart, and camera mount, for 100 Euros or so ! Much better...My scopes I got them for :- 317 (4 of them) : 55, 40, 45 and 80 Euros, depending on condition and period accessories included.- 310A : 75 Euros, in pristine condition and with it original custom Tektronix leather carrying case.- 531A : 50 Euros- 502 : 60 Euros- 502A : 45 Euros, because of the nasty physical damage mainly...- 515A : 60 Euros (soon to be delivered to me... )https://www.leboncoin.fr/bricolage/1513685901.htm/Then there is another 502A for only 50 Euros in great shape, and was working when last powered up "just" 2 years ago :https://www.leboncoin.fr/bricolage/1516218883.htm/I would gladly buy it of course, but local pick up only... damn... might try to convince him to ship it anyway, had success about that for a couple of my above scopes after all...And there is yet another 502A !https://www.leboncoin.fr/vi/1522469449.htm/80 Euros, a bit pricey but still reasonable, and of course can be negotiated a little bit... I contacted the seller. A son whose dad just died, he found the scope in the attic as can be seen in the picture... I asked him for more and better pics, more info on condition etc. Said he would get back to me... no news as of today, grrr... Says the sale is urgent, must be gone by the end of next week ! So hoping he will get back to me eventually !Then there is also this nice looking, 561A in working condition, for just 50 Euros :https://www.leboncoin.fr/vi/1498079673.htm/So yes, somehow these old tube Tek scopes can still be had for a reasonable amount... but that's the exception sadly. All other Tektronix models/generations, are way overpriced. For example, I like the early CRT TDS series (TDS 300/500/700), and they are wayyyyyyyy overpriced. Modest TDS 300 models go for hundreds of Euros, with not even proof that they actually pass the self test... go figure. I would love a TDS 380 in my collection, but forget it. I am much better off importing one from Ebay USA, pay silly high shipping and duty taxes, and I would still have lots of change left in my pockets ! LOL2200/2400 series scopes same storyHere sellers think that any old piece of junk is worth a million, regardless of what it is or what condition it's in, and they don't even make the effort to give it a quick clean and take decent/useful pics of the thing. People just are strange...

author: med6753
author_rank: Super Contributor
timestamp: November 18, 2018, 04:56:25 am
content: Yep, I hear you. People can be strange. But I have found some bargains on my local Craigslist. For example: A working military Tek 7603N with all 3 plug-ins for $75 USD. And my best score of all: A "non-working" Tek 2465 advertised for $75 USD. I offered $60 USD and it was accepted. I figured I'd either fix it or use it as parts mule for my current 2465. Anyway, I get it home and discover that the fuse and fuse cap are missing. I install one and hit power on and stood back. The scope powered up and passed all self tests! The owner had no idea what they had and I scored BIG TIME.I've since re-capped the PSU in that scope and it works perfectly.

author: Vince
author_rank: Super Contributor
timestamp: November 18, 2018, 05:15:47 am
content: Wow, incredible luck for that 2465 indeed ! I am jealous now !I would love a 2467B, it's on my list of old Tek scopes to add to my growing collection !No way I will find one in France, too rare and all I would find would be an untested/as is unit for a grand or something, I am sure... so I think I will just get one from Chuck Harris on TekScope. Still a good bit of money especially with international shipping, but at least I can trust his knowledge of the scope, and trust him at large, in his description of the scope, and what he did to it. This alone is priceless...Hopefully he will still be in business when I get round to saving some money to buy one ! Chuck if you are reading this (unlikely...), please don't retire just now, wait for a year or two ! LOL

author: tautech
author_rank: Super Contributor
timestamp: November 18, 2018, 06:42:03 am
content: Quote from: Vince on November 18, 2018, 05:15:47 amYeah med got the jammy git award for that score over in the TEA thread.

author: Vince
author_rank: Super Contributor
timestamp: February 09, 2025, 02:58:24 pm
content: GOOD MORNING !!!!Sorry if I woke you up... but that was precisely the intent !6+ years after getting that scope and writing this topic... I am finally back at it !Life got in the way but I am finally back to it, I am stubborn...6 years is a long time so let me recap the situation :I originally bought a vanilla 502 then shortly after, I found this 502A, for cheap, that clearly fell from the Eiffel tower then got run over by a truck, as a source of spares to help me fix the 502. Well, the 502, two of them actually, I finally fixed in the past few months, there :https://www.eevblog.com/forum/repair/(classic)-tektronix-502-scope-repair-restoration/msg5683467/#msg5683467So I don't need this 502A any longer you say ? Well... as much as I love the vanilla 502, for their historical value, being the first to come, and their slick look... while restoring them I discovered their deficiencies, idiosyncrasies, limitations... to the point that I have to be honest with myself and realise that the 502A was a much needed improvement over the 502, to the point that I don't really contemplate using a 502 as a "daily driver", but a 502A however feels to me like a much more credible option.So, I am now wanting to restore a 502A... but I don't think I will be restoring the one featured in this topic, because the cabinet has major physical damage which I am not equipped nor qualified to straighten. So, 3 years later, december 2021, I was lucky and found another 502A pretty locally, well, 200kms away that is, for a reasonable amount (75 Euros). Sold for parts, was stored in the guys woodworking shop, for years... However inside it looked decent and outside, no physical damage so... the idea is to use the first 502A for parts, which is what I bought it for initially anyway, and instead restore this second 502A.Better yet : a year later I bought yet another 502A, from the same seller, same price, but worse condition... it was really crusty so I immediately sealed its fate : a parts donour it would be. And boy did it give already many of its parts... when I was fixing this pair of vanilla 502.Here is a pic of the three 502A, from left to right in chronological order :- The first one, that started this topic, the one with a bent cabinet. Gathered much dust from sitting for 6 years...- Middle one : the one I will be restoring and which will be the subject of this topic from here on.- Rightmost one : crusty one for parts.So let's try to make a good 502A from those 3..... hopefully that will work out.I did do some initial work on that second scope 3 years ago when I got it. IIRC it had "some" life in it. However while restoring the 502 pair, I messed with all those three 502A, to the point that I don't know what state the one I want to restore, currently is in, what part I pulled from it, nor if its tubes are still good or original... So I have to assume it's a Frankenstein unit in an unknown state... so let's start from a clean sheet with it, taking it as it is today rather than trying to remember how it was 3 years ago or even 3 months ago...So, if you fancy a 502A restoration, be my guest !I intend to work on it pretty much immediately, non-stop until it's in a good enough state, to my taste.While restoring the 502 pair, I had so many problems to solve that I gained a good bit of experience with these scopes... so hopefully that will help me tackle that 502A in a fairly short time frame. I am hoping it won't take me 6 months to fix, because I already have another old Tek scope restoration in the pipeline that I am excited about as well...I do have one little problem though... I am unable to take decent pics of the work. A few months back my digital camera gave up the ghost after only 10 years of service. So since then I have been making do with my smartphone. Using it as a camera has proved to be an excruciating pain. I don't know how the average joe can be so happy with these machines, they make no sense... Anyway, very recently freaking phone started making super crappy pics, as you can see : they are extremely grainy/noisy, like I took the picture in the dark with the ISO set to 6400 or something silly like that... it's ridiculous.So I need to spend some cash getting a proper dedicated still camera to replace my old broken one. But that will take time... I need to read up on what's available on the market today, what to buy what not to buy...Max budget 300 Euros, picture resolution is of no concern as I only take pictures at 2MP typically, sometimes 3MP if needed, which is not often. However I care about picture quality : needs to be super sharp and the colours right and vibrant.I need replaceable lenses. I gather there is a new standard for that, " L mount" or something. Want a macro lens to take super close-up pictures of tiny components and PCBs, and a wide angle lens to take pics of the house interior : rooms are too small for a normal lens. A lens to view far away could be cool, so I can take pics of small birds at the back of my garden, from my kitchen window...

author: Vince
author_rank: Super Contributor
timestamp: February 09, 2025, 05:16:09 pm
content: OK let's get started on this scope...Gave the front panel a good clean, looks decent now. At the least I killed all germs accumulated in the past 60 years of its life, it's now both safe and pleasurable to work on...Inside it's got a thick layer of dust, will need a good clean / wash indeed, in the coming days, sometime next week.Had a quick look, first observations :- exterior : missing one of the two nuts that secure the air filter shroud.Inside :- CRT neck : the transparent piece of plastic piece that slides over the base of the CRT, has become light brown, brittle and turned to a crumble that's falling to a million bits... will need replacing.No big deal it's a standard part. Sadly it's a common issue on these scopes. For some reason I find that it tends to after only the "later" scopes, early '60s, but not the earlier scopes from the later '50s. So for instance all my 502A have this issue, but my two 502 are fine. Go figure.... newer is not always better then !Maybe the manufacturer of this part changed the composition of the plastic without telling Tek about it....As for the white nylon clamp that grabs this piece to make the CRT rotate... I will have to check but quite often it likes to break....- Power supply : under the deck there is a small axial electrolytic cap that spewed its guts. Nothing of immediate concern though : it's only used a secondary filtering, not primary. I could remove it and the scope would still work plenty fine enough for me to troubleshoot it, no worries.On the top side of that deck, the two small signal Germanium trannystors in the -6.3V power supply, are supposed to be the same type, but clearly aren't... so someone must have replace one of the two at some point...OK so next : let's power up this bad boy and see what it says....

author: Vince
author_rank: Super Contributor
timestamp: February 09, 2025, 05:21:54 pm
content: Piccies of the very dusty interior

author: Vince
author_rank: Super Contributor
timestamp: February 09, 2025, 05:22:36 pm
content: ...

author: Vince
author_rank: Super Contributor
timestamp: February 09, 2025, 05:25:31 pm
content: Pics of the front panel after cleaning.

author: Vince
author_rank: Super Contributor
timestamp: February 09, 2025, 06:16:02 pm
content: OK I went for broke and gave it power.... nothing on the screen.... quick look at the tube rectifiers in the CRT section, their heaters don't even light up. Measured voltage on their anodes... 150V or so.No HV, in a closed loop system...my worst nightmareIt's not a good start at all...

author: Vince
author_rank: Super Contributor
timestamp: February 09, 2025, 07:26:22 pm
content: After further inspection, found more minor stuff to refurbish :- Cabinet is missing a screw that secures the front end of one of the longitudinal stiffeners / beams at the bottom, not good. Easy enough to fix....- Missing shield on the oscillator tube in the CRT section.- Lower beam amplifier assembly : found two suspicious looking tubes. Might be some white stuff at their tops, inside. So might have leaked vacuum. They aren't glowing purple though, like often happens in such case. So I expect this amplifier might not work very well.... Again no worries, easy enough to replace : they are "regular" tubes, they aren't the highly sensitive, selected and matched pair of tubes in the pre-amp / front-end.OK then I checked the basics : supply voltages.The -150V reference supply was only slightly off at -155V or so. I adjusted it to spec.Now all supplies are good, including the unregulated 450V that supplies the CRT section but.... but for one supply : the little solid state -6.3V supply that powers the heaters of the 4 pre-amp tubes.It measured way off at -4V or so, and almost as much for ripple !So yeah, it needs immediate attention....Checked both rectifiers. They are modern silicon jobbies unlike the selenium rectifiers found in the older 502.You can't check them in situ because they are shorted by the low impedance of the transformer winding : low voltage means very few turns so very few ohms...So I lifted one leg on each of them... both of them turned out to be just fine.So... that leaves us with the big filter can cap : 4,000uF 16V.Lifted a wire, measured it and... verdict = 5µF or so ! Only 3 orders of magnitude lower, what could possibly go wrong !This is actually the very first time that one of these can caps is truly dead in these old Tek scopes. So far they always were good. A little tired of course, a bit more ripple than spec, but nowhere near failed like this one is....So, I replaced it quick and dirty style, just for trouble-shooting purposes of course, for now. I have no shortage of 4,700µF salvaged caps, so I put that in. I picked a 25V rated one rather than 16V, to be on the safe side, given that it's probably 40 years old...Result ? Problem solved, I now get -6.24V and next to no ripple. Lovely.OK so now that we know the power supplies are all fine, we can start working on the CRT section...Stay tuned.

author: TERRA Operative
author_rank: Super Contributor
timestamp: February 09, 2025, 11:26:45 pm
content: Nice work, will follow along. Unfortunately I don't have the space for tube scopes (and my requirements are for more precision and speed too), but I do so love tubes.When it comes to cleaning, Tek basically recommends a soft brush, mild soap (dish washing detergent) and a garden hose.https://w140.com/tekwiki/images/1/18/Tek-wet-washing.pdf

author: Vince
author_rank: Super Contributor
timestamp: February 10, 2025, 07:08:03 pm
content: Quote from: TERRA Operative on February 09, 2025, 11:26:45 pmWell My house is more of a closet (60m2) so most likely smaller than yours...Most Tek scopes are stacked right in the middle of the living room, where normal people would put a large dining table, and more scopes stored above and under the lab/work bench, which too resides in the living room, where normal people would put a big sofa. Plus tons more smaller TE filling my tiny 10m2 bedroom.So yeah, at least as much as you, I don't have the space for all this stuff and one day I will have to take drastic decisions that won't make me happy...But I try to postpone this moment as much as I can... I try to fool myself into thinking that once the garage is built, it will solve my problem. But basic calculations already show that this won't quite be the case...Quote from: TERRA Operative on February 09, 2025, 11:26:45 pmNope... that's a bad excuse !... of course I have more modern stuff and needs too, just like you or anyone really, but the old stuff is obviously for collection and fun, not for serious work (though they can still be useful in many cases). The old stuff has never been competing with newer stuff. Both co-exist happily...they both make me happy and both have a place in my heart and living room...Quote from: TERRA Operative on February 09, 2025, 11:26:45 pmYeah that's why I don't feel guilty for washing them ! That, plus the fact that experience shows me it's perfectly safe.Hell, if anything I am more CAUTIOUS than Tek themselves ! I would not dare doing some of what they recommend !At the other end of the spectrum, I can't believe they actually mention repainting the cabinet covers and polishing them !That's not cleaning, that's nerd restoration.. even more insane when you consider they wrote this paper when these scopes were well, pretty much brand new !I do plan on gearing for painting, as my old car needs a lot of attention in this department. That would enable me to have a go at repainting all my restored Tek scopes.I also plan on learing leather stuff so I can make brand new leather carry handle.The brightwork for the handles also needs refinishing so I plan on getting into DIY clading, electrodeposition, whatever you call it... strip the rust and chrome remains of the handle bits, then rechrome them.Same treatment for the big screw that hold the side panel in place. They need refinishing.Need to find a source of imperial screw that match perfectly the shape and finish of all those found in these Tek scopesThat will take time and money, and will require a garage.. so for now my restorations are limited to cleaning and fixing the electrical side of things, but later on I will revisit all of them to make the covers and handles brand spanking new. That will be the final touch

author: themadhippy
author_rank: Super Contributor
timestamp: February 10, 2025, 08:16:24 pm
content: Quoteor get a lathe

author: Vince
author_rank: Super Contributor
timestamp: February 10, 2025, 08:24:00 pm
content: I intend to get one, but that's not going to be much help to make screws... only the threaded part, which is not where the problem lies.the problem is having a head that matches perfectly the shape and finish of the original one. That, is the hard part...Not to mention that it would be way too much work. Buying them in bulk is much more cost and time efficient than anything I could make myself...

author: Zoli
author_rank: Frequent Contributor
timestamp: February 11, 2025, 07:17:06 am
content: Quote from: Vince on February 10, 2025, 07:08:03 pmLook around onMcMaster-Carr; to give you an example, the missing nut from the fan cover most likely is a 6-32 plated steel acorn nut.

author: Vince
author_rank: Super Contributor
timestamp: February 11, 2025, 08:08:08 pm
content: Quote from: Zoli on February 11, 2025, 07:17:06 amAh, that website looks familiar, think someone on here pointed me to it a few years ago... thanks for the reminder.Too bad it's an American website, cost of importing and shipping would most likely be prohibitive.Still a nice resource though, as they show so many different types of screws, with pictures, so I can easily identify the screws I am interested in."Acorn"/cap nut is an example... no way in hell I could have guessed how these things were called...Too bad though, that they don't provide actual example pictures of what the various finishes look like, so I can be 100% sure of what it is that Tek used.I think Factory gave me the link to a UK website that sells small H/W too, but now with Brexit it means I still would have to go through the import shit, though overall it might still come out cheaper than importing from the US. If I do have to resort to importing though, I would have to make the order as big as possible to make it worth the trouble. Would have to prepare a list of as many nuts and screws found in these Tek scopes, as possible, and order 100 or 200 of each...From the website, looks like for the screws that are visible from the outside of the scope, I would need Philips "pan" heads, as well as Philips extra-wide Truss heads and maybe round heads as well.Finish is super shiny so maybe chrome plated I guess.As for the inside of the scope, looks like they used slotted pan heads. Looks like there are a few variations of the shape of a "pan" head, but the pictures are clear enough. Finish is dull light grey, whatever technically that is...That would cover 90% of the needs. Then Acorn nuts for the air filter housing as you said, and some Philips counter sunk heads to hold all the HV shields in place as well. Oh and some "panel" nuts for the front panel, and why not also a bunch of set screws to replace the rusty ones in all the knobs...Hmm yeah, would be so cool if I could have an entire collection / stock of every screw type Tek used... I could restore my scopes like brand new in a heart beat, how marvellous....

author: tautech
author_rank: Super Contributor
timestamp: February 11, 2025, 09:38:23 pm
content: Dome nuts are also another description.

author: Vince
author_rank: Super Contributor
timestamp: February 11, 2025, 09:43:55 pm
content: Here in FrogLand we call them "Blind" nuts ...

author: Zoli
author_rank: Frequent Contributor
timestamp: February 12, 2025, 02:30:45 am
content: Quote from: Vince on February 11, 2025, 08:08:08 pmTypically, they provide 3D models(.step), viewable with FreeCAD; attached is zinc-plated steel 6-32 acorn nut(love the identity crisis: is it acorn or is it nut).

author: George Edmonds
author_rank: Frequent Contributor
timestamp: February 12, 2025, 08:09:36 am
content: HiDome nuts are the correct description in Europe.Look on that auction site, they are available in various UNC threads made from A2 stainless steel. Check that they are 6/32As are most other types of UNC fasteners, the set screws (grub screws) are probably 4/40 UNC.G Edmonds

author: factory
author_rank: Super Contributor
timestamp: February 12, 2025, 06:14:28 pm
content: Quote from: Vince on February 11, 2025, 08:08:08 pmIt was Accu who have imperial and UN stuff in stainless steel, seems they have a French version of their website, but I don't need translate to work out they are taking the piss with shipping, shipping to France seems more expensive than to the US.Maybe because it's a faster than needed service.https://accu-components.com/fr/https://www.accu.co.uk/If you want some samples from them, let me know as I need to order some parts from them (but haven't got round to it), I could add a few to the package, with your scope power cord & CRT cover.Of course if someone knows of an equivalent shop in France or the EU, with a wide range of imperial and UN parts stocked in the EU, let Vince know.David

author: TimFox
author_rank: Super Contributor
timestamp: February 12, 2025, 06:25:10 pm
content: Note that the dome cap over the threaded nut in "acorn" or "dome" nuts is not strong: it only exists to cover the threaded hole and the screw therein.I once had to cope with a design that used the dome to pull on the male screw inside, which failed quickly when reasonable force was applied to the screw.

author: Vince
author_rank: Super Contributor
timestamp: February 12, 2025, 06:55:56 pm
content: Quote from: factory on February 12, 2025, 06:14:28 pmThanks David.Yes, "Accu" that rings a bell now.This week-end I will try and put together a list / details of every nut and screw in these Tek scopes, at least the ones I know I regularly want to replace.HP scope : I have eventually been sent an old HP cord by a kind TEA member from Germany. I am still in need of the CRT cover though !

author: Vince
author_rank: Super Contributor
timestamp: February 12, 2025, 07:20:43 pm
content: Quote from: Zoli on February 12, 2025, 02:30:45 amThe CAD model won't tell me what the finishes look like, though... unless they come with a photo realistic renderingCan't install Freecad sadly... 3 days ago I tried to install a Hex file editor on my Linux machine but the package management software somehow won't work anymore, I fear probably due to a recent silent update I guess...I hope they will fix the thing but not sure because I also got a message saying they will now stop updating it (XUbuntu 23.10).... only 6 months, if even that, after I installed that version of the OS. Sucks...I am reluctant to upgrade the OS to the latest version because I did try at the time and it failed to boot (23.10 was the most recent that would boot). I think a problem with the modern silly stuff in the motherboard, EFI BIOS something, that needs settings I don't understand, and special partitioning I don't understand either. Information on the web about it is confusing and self contradicting, and I fear if I update I will lose the entire machine rather than just package management.... oh the joys of computing...Still better than Windows 11 I updated my work computer with today. Laptop is now slower and they changed the user interface without asking me, and I can't find a way to make it look and behave like it used to. Drives me nuts and lowered my productivity. Rule #1 : once the computer works, do - not - touch - it. Sadly, for my Linux box after 16 years I had too, S/W was becoming obsolete and using the web was getting more and more difficult...Anyway, no Freecad or any new S/W for me in the near future....

author: George Edmonds
author_rank: Frequent Contributor
timestamp: February 12, 2025, 07:38:09 pm
content: HiThe ebay listings are from China with free postage or minimal posting at least to the UK, maybe France is different,A2 stainless is normally a semi matt material.G Edmonds

author: George Edmonds
author_rank: Frequent Contributor
timestamp: February 12, 2025, 08:34:59 pm
content: Hi AllPlease note that the screw threads used by Tektronix are NOT Imperial.Imperial threads areBSW British Standard Whitworth The Worlds first thread standard.BSF British Standard Fine.BA British Association.Tektronix predominantly used, in the early days, UNC Unified National Course threads. They then went, as did most world wide manufactures, to ISO International Standards Organisation threads. This was done in the large part as a result of NATO and the need for a common standard thread.The early Tektronix screws are quite soft and particularly with the cross head ones the correct American Philips screw divers MUST be used if you do not want to damage them.G Edmonds

author: Vince
author_rank: Super Contributor
timestamp: February 12, 2025, 08:42:35 pm
content: Quote from: George Edmonds on February 12, 2025, 07:38:09 pmThanks. stainless steel makes more sense than chrome-plated I guess. Just looked at the exterior screws on my Tek scopes and yeah, they aren't AS shiny as chrome... SS is probably what it is.I will give that a shot then. I googled a bit about A2 vs A4. The chemical composition is 99.9% identical which leads to no perceptible difference in the visual appearance, most of the finish is due to the polishing, they say...A4 is just more expensive as it's extra corrosion resistant, for marine purposes.So I guess A2 is probably what Tek used and what I should try first...no reason to spend extra money on A4. Tek scopes are boat anchors but anchors that actually never see salty winds never mind get immersed in sea water....

author: Vince
author_rank: Super Contributor
timestamp: February 12, 2025, 08:47:23 pm
content: Quote from: George Edmonds on February 12, 2025, 08:34:59 pmOh yeah I remember on TEA a few years ago we already discussed this GIGANTIC can of worms, so many standards !When I said "Imperial", I guess it was my bad. I only meant it by opposition to "Metric". That is, thread pitch and diameters expressed in fractions of inches rather than millimeters...From what I gather, UNC/UNF is most of what's available these days and fits old american TE just fine, even if perhaps in some cases, not always, strictly speaking, the exact same standards. It's "good enough for the purpose", shall we say. Perfection is unattainable so we must be reasonable and do the best we can within reason ?!So I guess I should not say "imperial" but rather "inch" fasteners or something ?!Luckily most Tek service manuals include a mechanical parts list that specifies diameters, length and pitch and head style, so I don't have to buy thread gauges to measure all the screws myself...

author: George Edmonds
author_rank: Frequent Contributor
timestamp: February 12, 2025, 09:08:53 pm
content: Hi againUNC and UNF were products of world war two and ratified as a standard by the US, Canada and the UK in 1949. During world war two all REME mechanics/fitters had to have two tool kits as the spanner sizes used on US Tanks and UK Tanks were not interchangeable. In the 1970 to 1990 time period I was a self employed customer support engineer for an old British company an American company and two French companies as a result I had to carry three tool kits.G Edmonds

author: Vince
author_rank: Super Contributor
timestamp: February 12, 2025, 09:13:49 pm
content: Interesting.So it's strange that we had to deal with so many imperial standards when UNC/UNF was already accepted by the anglo-saxon world such a long time ago !I don't understand why US and UK tanks didn't use the same spanners, even though they both used fractions of inches ?You mean they did not use the same fractions ? Like say, one was using say 5/16 and the other something close but not quite the same, like say 9 or 11/32 ?!That's pervert...

author: TimFox
author_rank: Super Contributor
timestamp: February 12, 2025, 09:35:09 pm
content: As many posts have reminded us, “Imperial” and “US Conventional” units are similar inch-based units, but not synonymous.The “Anglo-Saxon” world is not monolithic.Wikipedia covers screw history in several chapters. The UK early on adopted a screw form with 55oangle (anyone know why?), and the US generated an early spec (ca. 1864) with a 60oangle. That “USS” or United States Standard spec was essentially the same as what is now UNC (coarse thread for the current Unified Thread Standard) and the UTS incorporated the previous SAE spec as UNF (fine thread). The Unified threads were formally adopted in North America in 1949.The basic thread form is the same for UN and ISO screws, except that the latter are defined in metric units.In general, the common ISO sizes tend to have finer pitch than the UNC sizes.

author: George Edmonds
author_rank: Frequent Contributor
timestamp: February 12, 2025, 09:59:48 pm
content: Hi VinceAmerican spanner sizes are fractions of an inch across flats, but true Imperial spanner sizes use a complex formula based on thread diameter to get the measurement across flats. It all goes back to the standardisation of threads and maximum bolt strength work carried out by Whitworth.Before the work of Whitworth nuts and bolts were hand made by individual blacksmiths and were not interchangeable.In reply to Tim Fox Whitworth chose a 55 degree thread angle as it gave the maximum bolt strength in his tests. Whitworth set up the worlds first materials testing laboratory, he also designed the first millionth of an inch measuring machine. This is taking me back to my collage days in the very early 1960’sThe now largely redundant BA thread was actually based on an old French metric standard with a thread angle of 49 degrees, if my memory is correct.G Edmonds

author: TimFox
author_rank: Super Contributor
timestamp: February 12, 2025, 10:10:00 pm
content: Thanks for the information about Whitworth thread form.The UK and US thread definitions started during the rise of true mass production in the 19th century.

author: Vince
author_rank: Super Contributor
timestamp: February 12, 2025, 10:13:56 pm
content: Thanks George, a living encyclopedia !!

author: Vince
author_rank: Super Contributor
timestamp: February 15, 2025, 01:40:33 pm
content: Today is somehow nice. Dry and sunny, not too cold, no wind.... last such day was so long ago that I can't even remember when it was. 6 months ago maybe....and it coincides with a week-end day at that so... in short, if I don't wash the scope today, next opportunity might not come up before many many weeks....So I just prepared the scope, in the usual manner.Removed CRT and related bits.Removed the fan and air filter.Removed all the tubes.Removed handle barRemoved all HV shields.Good news : the white nylon clamp that rotates the CRT, is not broken, for a change.Bad news : the base of the CRT is loose !That's now two 502 CRTs with this problem then, arrrrrrrrrgh....I have only one CRT left, so here is hoping that one will be good... if it's not, then I will have to ask one of my vanilla 502 to give his....... or learn how to harmlessly remove the base so I can reglue it.Other than that :- I replaced the two missing screws that were holding the front of the bottom left cabinet stiffener.Really had to do it because without the handle bar, the scope was now left with only one single longitudinal stiffener, making the scope too weak / fragile.- Look at the two pots that control the focus for the upper and lower beams : somehow they are covered in some gunk, that the other HV pots next to them, aren't...

author: TERRA Operative
author_rank: Super Contributor
timestamp: February 15, 2025, 02:31:02 pm
content: Re. the loose CRT bases, you might be able to suck the solder out of the pins and carefully remove the base, then some cleaning and a bit of epoxy to glue it back in again, resolder and should be happy days.

author: factory
author_rank: Super Contributor
timestamp: February 15, 2025, 05:42:58 pm
content: He might be concerned as to how to prevent the glass cracking when soldering/desoldering, this is what happened with the HP120, which he now needs a replacement CRT for, or a donor scope.Many of my HP scopes suffer the same loose base problem, I do have a dead CRT for experimenting with repairs though. Most of the later ones use a trace rotation coil with internal graticule, only the really early ones have the separate graticule plate & required turning the tube for trace alignment.For epoxy resin we used both Araldite 2011 & 2012 at work (one was slow, the other fast set), people would often borrow the mixing gun, single use mixing nozzles & 50mL cartridges for home projects, this is not an option anymore, cost of the industrial grade tubes is very high for the amount of resin needed and it expires after a few years, leading to a lot of waste, instead I buy the small consumer grade "rapid" in 15mL tubes & mix by hand, this is quite messy.2026 looks a better choice for glass & is flexible, but I'm not finding a match to the consumer products.David

author: George Edmonds
author_rank: Frequent Contributor
timestamp: February 15, 2025, 06:12:18 pm
content: Hi AllNEVER remove a CRT base, only tears will result.I would suggest the use of solvent based Impact Adhesive, sold in the UK as EVO-Stick in small tubes. Or better still use the product made by Sikaflex for bonding in car windscreens as both always remain flexible.G Edmonds

author: factory
author_rank: Super Contributor
timestamp: February 15, 2025, 06:32:06 pm
content: Yesavoidingremoval of bases from CRTs or valves/tubes is best, the other forum recommended carefully cleaning the old loose glue out if possible, along with many different suggestions for what glue to use (everyone has their own preference), hence the experimentation on something that is dead or unusable first.It's worth mentioning again to NEVER use superglue.But sometimes you might need to replace a broken base, or fix a broken wire or terminal and removal is the only option if it's really badly damaged. A youtube repair channel successfully did this with an ancient TV CRT, this is a high risk operation of course, he took the replacement base from a dead/weak tube, I won't bother mentioning the channel as it seems to trigger some people on here.David

author: Vince
author_rank: Super Contributor
timestamp: February 16, 2025, 02:47:13 pm
content: Thanks people for your inputs. What I take away from that is :- Better not remove the base since it's intact.- Maybe use a dental pick to remove the visible glue from the edge of the base- Use that little "cavity" between the glass and base, to apply a thick bead of some glue... but not superglue.For now I will just align that CRT as best I can without putting too much strain on the base/wires, or just replace the CRT, and buy time.Scope is now clean. Washing alone can't reverse 60 years of wear and tear and storage in a non-heated environment, so we do have corrosion on the the top side of the lower deck as often, and on the 3 shafts that connect some front panel controls to the back of the scope, but I will live with that. It looks clean and that was the purpose...Still not bad for a 60 year old scope, I say.As always, will let it dry for a few days before putting it back together and powering it up, later next week.

author: m k
author_rank: Super Contributor
timestamp: February 17, 2025, 07:12:13 am
content: Super-glue is fine if you do it right, but you can't do it right.You must press it for thinning the layer, how would you do that.Old commercial has that picture of a crane lifted car.Fine, but what that picture actually has.From above there is a hook loop with flat bottom, then super-glue, then paint and then steel of the roof.So it's finally paint that keeps the car hanging, if it can.Key here is a surface area of a connection.So better use something that can penetrate and operate without any external help.It's that connected surface that is twisting the CRT.Other major thing is resting stress/tension.And again super-glue is a bad thing, as it is also many times operating very fast.So work time has a meaning here.Single or dual component stuff.I'd say that single has less air bubbles, and Sika has good products, obviously.

author: Zoli
author_rank: Frequent Contributor
timestamp: February 17, 2025, 04:30:11 pm
content: Quote from: Vince on February 16, 2025, 02:47:13 pmUse acid-free RTV(silicone).

author: Vince
author_rank: Super Contributor
timestamp: February 17, 2025, 05:11:10 pm
content: Yeah but silicone is flexible, and we need the base obviously make "one" with the glass, it's the whole point, so that rotating the base also rotates the CRT...Unless I am missing something of course...

author: factory
author_rank: Super Contributor
timestamp: February 17, 2025, 06:39:50 pm
content: Yes it's flexible, but not so flexible that you can rotate the base.Slight flex in the filler is preferable, unless you have access to the original glue, that was carefully chosen to match the thermal expansion properties of the different materials, remember this is the warm end of the tube.Quote from: m k on February 17, 2025, 07:12:13 amRead the first post here, there are many other posts with warnings too;https://www.vintage-radio.net/forum/showthread.php?t=400QuoteQuoteDavid

author: Zoli
author_rank: Frequent Contributor
timestamp: February 17, 2025, 07:44:14 pm
content: In the early 90's I've changed sockets on quite a few EL34's(6, IIRC), fixed with RTV; they happily lived for a few more years on the road with everyday (ab)use.

author: Vince
author_rank: Super Contributor
timestamp: February 17, 2025, 07:50:03 pm
content: Quote from: factory on February 17, 2025, 06:39:50 pmOK OK.... so just so we are on the same page, we are talking about the silicone sealant cartridges that H/W stores sell for use in the bathroom, right ?Like this one (from my local store) ?https://www.leroymerlin.fr/produits/materiaux/etancheite-des-murs-et-sols/silicone-et-mastic-etancheite/silicone/mastic-etancheite-cuisine-et-bain-axton-blanc-280-ml-90201927.htmlI see they sell two types of suych silicon cartridges : "acétique" or "non-acétique". Whatever that means.Quote from: factory on February 15, 2025, 05:42:58 pmThese big cartridges are way too bulky for delicate jobs like CRTs so I think I would rather use 2K araldite like you mentioned.Google found me 50ml kits for the Araldite 2012 :https://www.siliconecomposite.com/les-colles-et-adhesifs/araldite-2011-epoxy-bi-composant.html... but at nearly 40 Euros it's quite expensive. But at least the option is there, and with 50ml I guess I have enough to serial-glue half a dozen CRTs.... so the cost per CRT is bearable.Then I searched for the "Rapid" consumer version you mentioned and found this on Amazon :Two 15ml tubes, says it does plastics and glass... is that the one you used ?https://www.amazon.fr/Araldite%C2%AE-parties-rapide-R%C3%A9sine-adh%C3%A9sif/dp/B072KS9M3T/ref=asc_df_B072KS9M3T13 Euros, more affordable for sure.... but why the hell don't they provide a syringe and nozzles like everybody else ?!

author: Zoli
author_rank: Frequent Contributor
timestamp: February 17, 2025, 09:00:54 pm
content: Quote from: Vince on February 17, 2025, 07:50:03 pmYes, I was talking about similar stuff, such as Locttite 234323(https://www.digikey.ca/en/products/detail/loctite/234323/4833001). As I've told initially, non-acidic(that's "non-acétique" for Frogland, since the other type of RTV*releases acetic acid during vulcanization) is preferred. Placement: one drop beside each pin.*RoomTemperatureVulcanization

author: factory
author_rank: Super Contributor
timestamp: February 17, 2025, 09:15:38 pm
content: Quote from: Vince on February 17, 2025, 07:50:03 pmFor use with electronics the non-acétique (non acid cure) is needed, normal bathroom sealant releases acetic acid as it cures/sets, this is bad news for any wiring & leads. Make sure there is no acid, acetic or other kinds.The electronics supplier have smaller tubes, we had some pricy stuff at work Dow Corning 3145, I asked for a 90ml tube, the stupid person above me ordered 2x of the 310ml cartridges, we only used about a third of one tube, the rest expired & set solid in the cartridge after a few years, the unopened one had gone the same way, what a waste.Maybe someone has a recommendation for some lower cost non corrosive/non-acidic RTV in small toothpaste size tubes, it's a lot less messy than mixing epoxy.Edit: above post is a good choice for non acid RTV.Quote from: Vince on February 17, 2025, 07:50:03 pmYes that consumer grade "rapid" araldite is what I have at home, it's horribly messy to mix & apply, all versions I've used are quite runny until it sets a bit, electrical tape can be used to keep it in place until it's fully set. Rotating the item was needed to keep it from flowing too far away from where it was applied, with the fast 2012 or rapid one it starts to set after 5 minutes or so. Don't bother with the slow 2011 version it takes too long to start setting.With the cartridge versions, the piece you remove to open the cartridge goes back in place to seal it (one way round only, or it's stuck for life), or I used to leave the used mixing nozzle in place till next time, remove the cartridge from the applicator gun and fit a new nozzle when next required.I'm liking the price of the 50ml glue gun/pistol applicator, to use with the araldite or clone cartridges on Amazon, the nozzles are dirt cheap too, I think I need to get one of those but not from Amazon as I don't use them.Note I've not tried any repairs to my CRTs, so can't comment how well they work. I'm thinking of experimenting with something low value such as car lamps would be a good idea, to make sure it doesn't cause any heat related cracking.P.S. If I had some superglue, I would test to prove the theory that it guarantees cracking.David

author: Zoli
author_rank: Frequent Contributor
timestamp: February 17, 2025, 10:39:31 pm
content: Quote from: factory on February 17, 2025, 09:15:38 pmI've just observed that following my link gives almost double price than making an RTV search on the digikey site; take note, and don't overpay.

author: Vince
author_rank: Super Contributor
timestamp: February 18, 2025, 08:17:28 pm
content: Quote from: Zoli on February 17, 2025, 09:00:54 pmAhhhh...... thanks. I am no chemist so I had to play it safe and assume that "acétique" meant something other than "acidic" because well, not the same word...Quote from: Zoli on February 17, 2025, 09:00:54 pmOhhhhh.... thanks for that ! I keep hearing about RTV this RTV that, on american Youtube channels, not knowing what they mean.So... basically, it encompasses just about any type of glue/sealant that's NOT a two part product ?So any type of cartridge you can get at H/W stores : polyurethane, acrylic, silicone, polymer... you just squeeze the stuff out, apply it and hope for the best.So RTV can be pretty much..95% of what's being sold to consumers, in practice...I guess I have enough advice to buy some glue now... thanks people.Will bookmark this discussion for future reference...

author: TimFox
author_rank: Super Contributor
timestamp: February 18, 2025, 10:38:47 pm
content: The acid-containing RTV materials normally useacetic acid, which is why they smell like vinegar before they cure fully.seehttps://en.wikipedia.org/wiki/RTV_silicone

author: Zoli
author_rank: Frequent Contributor
timestamp: February 19, 2025, 05:45:46 am
content: Quote from: Vince on February 18, 2025, 08:17:28 pmRTV refers to a family of siliconerubberproducts, since I don't know if anything else then rubber can be vulcanized.Attached is one entry to therubberrabbit hole.

author: m k
author_rank: Super Contributor
timestamp: February 19, 2025, 02:31:01 pm
content: Quote from: factory on February 17, 2025, 06:39:50 pmYes, I've obviously misunderstood something with Tektronics ceramics and this connection thingy.But no need to go any further with it here, I'll figure it out somewhere else.And superglue is no good here.QuoteI've seen when the side of CRT tube neck has given up.Around a finger side area is cracked off, but can't remember anything of the adhesion/connection.It's also possible that somebody tried to turn a magnetic coil pack without loosing it first.For synthetic rubber,seems that I've misunderstood it also.I've used it for butyl stuff only, but it seems to be anything that has a rubber like end product.Somehow I can't use the term for silicone, no matter what.E,Do I get it now, the thing is to add glue in between pins and their glass surroundings?If so then that is pretty delicate place to add stuff.To examples,welded and bolted railroad tracks and freezing water in a bedrock hole.