Tis a sad fate indeed suffered by all too many rectifiers .....


I trust my x wife 100 times more than I trust any electrolytic cap that's as old as I am ;)

The reason you trust your wife more is because you are kinder to her than your electrolytics! If you read earlier thru the thread, the patient and proper reforming of the dielectric is the key. How long running time will it take to convince you the capacitors are okay?

:thmbsp: I was more or less joking with you , if you noticed I said "my x wife" , no kinder there my friend .

Kinda like your "dry" joke , I guess humor & electrolytics just don't mix :D


;) and yes , I am interested in how long the reformed caps live .

I wish I could find the pictures I have of some old caps I took apart.

When I say rotted I mean exactly that, if you unroll the foil there are areas where the aluminum has been eaten away, with gaps in the foil, there are often lumps from the crystals that have formed that leave dents on the paper insulator, I would guess it's these dents, if they get bad enough, that press through the insulator and cause shorts. I have seen several caps where the connecting leads between the foil and the lugs have corroded completely in two causing an open.

And of course I have opened some 40's caps up to find they are still wet and pristine inside, but that is the exception. I imagine the type of storage and the length of time they have been inactive plays a part.

I'm not trying to be contrary, it's an interesting project to try minimal repairs, but I think it is a gamble that they will continue to work, not a big deal since this is a hobby and if it craps out it's not a big issue.

I'm an amateur hobbyist, so it's usually easier for me to just change them and be done with it rather than wonder if that odd little problem I'm having is being caused by an old capacitor.

I have always been of the impression that electrolytics that are bone dry
cannot out damn bug! OUT! you damn cockroach get out of my keyboard reform.
Reforming is supposed to take solvent.

I have seen caps that were bone dry and had normal capacitance and
took rated voltage, but I assumed that they were that way before going dry.
What think you people.

I hope you fry, damn bug ... wait, no, that might hurt the keyboard. OUT!
Damn coronavirus, keeping the exterminators away!

:drunk: Not fair to be drinking and not share with your old TV buddies .....

Yeah!
https://media.makeameme.org/created/...eer-5bb914.jpg

:beer:

:beerchug:

:drunk:

https://www.youtube.com/results?sear...ry=i+like+beer

I ran the 721TS another 5 hours today. Ran three movies and film shorts from a TCM DVD.

Electrolytics still fine. Each running cool. Rest of the wax capacitors I chose to reprieve okay. Yesterday when I tested the resistors in the video amplifier, all were within tolerance.

When I obtained this set the width adjustment was set for maximum width. As is, the image on the 10BP4 just fills the mask. Might look around the sweep section to investigate. Certainly the width and height have remained constant over the period of my bench test.

Consider this set sat in a partially insulated attic for over 50 years and the sat in storage for a further seven. I am fortunate it had a quiet existence which may partially explain why much of the original componentry has survived.

Will keep it running to determine if anything will fail. I suppose 35 hours is insufficient to prove that original electrolytics aren't salvageable. So let's give it another 35 hours. I am curious to see myself.

Here are another couple of screenshots from a few minutes ago.

The set has been on for six hours today. Finished off the Judy Garland - Mickey Rooney DVDs. Looking at some late 20's Vitaphone shorts. Here is Blossom Seeley in 1927.

The original electrolytics are still running cool and fine after over 41 hours. Still waiting for them to fail.

Finished off another 8 hours running DVDs on the 721TS now reaching 43 hours since reforming the original electrolytic capacitors. I am impressed with the performance of this set with only 21 tubes. Lots of audio volume, no buzz likely because of its full split sound design. The video is sharp but the resolution above 3MHz is missing since the design has only three IF stages. The lack of any AGC is not a problem with no analog over the air available. Would have been curious how it would have been necessary to adjust the contrast control when switching between local and fringe stations.

I recall using my RCA 8T243 (kcs28 chassis) for analog over the air. This is the set I have kept the longest, having been given it in 1970. (It incidentally still runs on its ordinal elwctrolytics). The high class RCA design for 1948-49 sets feature full 4 MHz resolution, a more sophisticated sync separator and RCA's first television AGC solution using peak sync detection. But most impressive were the dual adjacent channel traps. Despite the wider bandwidth, the adjacent channel rejection was so good, you were able to receive deep fringe signals immediately adjacent to strong local stations. The 721TS had no adjacent channel traps. No problem with a modulator now feeding the set.

But the RCA sets in the late forties were built like tanks. Later design sets, especially with larger screens and with larger deflection angle CRTs put a stress on all of the components which would result in reduced reliability.

So tomorrow we should hopefully be able to reach 50 hours on the original 73 year old electrolytic capacitors.

Cool, I've never even put 50 hours on any of my old sets.

Closest thing would be a cheap 19" RCA from 1970 that I have been using the last couple months to watch old shows on DVD.
Recapped the films but not the Filter, got a dozen or so hours so far but the rejuvenated CRT is likely to die before the caps do.

It is up to 45 hours now. I investigated the picture width problem. I just performed routine voltage measurement and found the horizontal oscillator plate voltage a little low. The 120kohm plate dropping resistor had drifted upward to 150kohm. I replaced it with another 120 kohm 1 watt carbon composition resistor (originality of course) and the width was restored.

I saw the width control adjustment was screwed all the way in to maximum before the set was allegedly retired to the attic 60 years ago. So this must have been an old fault.

I have reverted testing with an older expiring 10BP4 to continue waiting for the anticipated expiry of the electrolytics. I want no more hours than necessary on the CRT.

Somehow I don't think there is going to be a failure. The electrolytics are running cool. And this hasn't been luck or good fortune: my two other pre-1950 RCA tv's have all their original electrolytics and run fine. It is running now and has done another 10 hours continuous running today.

The key is patience reforming the capacitors. That is leaving them attached to a light trickle current 24 hours and slowly reaching the rated maximum voltage. If you do not hurry the process, the capacitors should survive. And I am only speaking for RCA sets: I cannot speak for other manufacturer's sets designed to a budget.

Will aim for 55 hours running time tomorrow.

When I started in the TV biz in the early 70s, I replaced many hundreds of can electrics in all brands, RCAs included. Some were from the 50s but most were from the 60s.

Recently, I've restuffed cans that were fine, and every time a little investigation reveals decay in both the foil and the paper. It's actually amazing they work at all at this age.

No amount of reforming will improve the deterioration of the paper or foil or reconstitute dried electrolyte.

John

What are your thoughts on the air core high voltage transformer that RCA started using around 1950? I'm assuming it had something to do with the new wider deflection CRT's, although other manufactures seemed to be using something like a ferrite core flyback transformer with good success. It appears that they used that air core on everything from a 12" to 19" CRT.

Can you quantify the decay you have seen? I mean, what specifically quantifies the intenal degradation of a capacitor that deems it unservicable to you?

Do you replace the resistors and full tube compliment as well, even though they function out of tolerance? The curious thing here is that these reformed old electrolytics after dozens of hours test within original tolerance for leakage and capacity. The vacuum tubes from day one lead a downward spiral and after 13 years of heavy use have degraded.

Is it not of interest that after 43 hours continuous operation the capacitors still run cool and are within the original specifications? This is not loose speculation.

Have you tried to patiently reform the capacitors as I have outlined here? Surely old chassis's are available to try. And if it is your own personal set, what is there to lose? Worried about the power transformer or rectifier? You can always insert a slow blow fuse.

I will reitterate that the capacitors remain healthy after 43 hours continuous operation. How many hours operation will it take to convince?

Yes. The foil as it's unwrapped is generally full of pin holes or outright disintegrates when unwrapped. The paper was mostly just falling apart. How these filters worked at all is amazing.

No. Resistors, tubes, inductors etc. are different animals.

Which is still higher than a new electrolytic when it comes to leakage readings, and you are talking about a capacitor that is working right now. What happens six months from now?

Tubes wear out faster than other parts yes, which is why they were put in sockets in most cases. But a worn out tube doesn't generally destroy a transformer when it wears out. Sure, certain tube failures cause collateral damage, but even a brand new tube can do that.


In the interest of discussion perhaps, but I have no interest in using this single case anecdotal evidence to change what I know as fact.

Yes. I used to try to save a buck like anyone else. When I first started screwing around with tube radios for my customers in the 80s I would do this. I got tired of seeing the same radio back months or a year later with a bad electrolytic or bad paper cap.

When I restore a radio for a customer, I guarantee it for a full year except for vacuum tubes.


There is no amount of hours for this one TV that will change my mind on this. The 51 Andrea I'm finishing up has 5 of its original 9 can filters still installed. Two of them let go after dozens of hours of working perfectly.

The other two I restuffed for restoration sake were physically degrading in the manner I described in my first paragraph.

I'm not one to change every part because it's what is expected, I change parts that are either defective or have a history of failing. I have a 1929 Radiola in my living room that is running on all original parts, capacitors included with the exception of 5 of it's globe tubes. The Radiola was built in an era before electrolytics and the capacitors were made with rice paper instead of rag paper. Radiola experts say don't change them unless necessary and indeed, my Radiola has been running 15 years in the time I've had it on original caps.

John

That suggests another study which is to reform an old capacitor and then take it apart to analyse it. I still do not understand your reasoning that if the capacitor fuctio n's within original s specifications how it could function at all with pinholes? How can you be sure that unless you disassemble a new capacitor, it doesn't haved pinholes as well

As pointed out, I have owned an RCA 8T243 from 1949 for 50 years and it retains its original electrolytics. And they remain fine.

Your statement points only to your anecdotal evidence. You are by rote used to changing the capacitors. And as this is supposed to be a hobby dealing with archaic artifacts (ancient TVs) and not with a NASA space project, what is the harm in attempting to retain the set's originality? I am the owner and I will maintain a watchful eye.

But as I earlier pointed out, this is not for a customer. This is for myself. I would agree with you if the set was out of your control, yes the capacitors should be changed.

And it has nothing to do with saving a few bucks. It is the aspect beyond simply cabinet aesthetics, to retain the historical originality of the set and to make "intelligent" decisions what to retain and to replace. As a professional Electronics Engineer with an MSEE, I precisely know what I am doing.

I cannot comment on the quality of the capacitors used or whether you reformed the capacitors properly. I contend that the capacitors you attempted to use did not reform properly as can be determined by properly applying a stress test of leakage measurement at full rated voltage. If determined that the capacitor is in anyway compromised it must be replaced. In my 721TS case, after reforming, the leakage was well within spec at full rated voltage, which encouraged me to run this test.

Anyhow I shall run the set for another 10 hours today. After it goes beyond 50 hours, I shall test some of the electrolytics and confirm whether or not the capacitors have degraded in capacity or leakage over the 50 hours running time.

That's kind of the whole point, isn't it? Your RCA may never have those filters fail and I hope that's what the end result is.

But even when rebuilding something for myself, I do it with the expectation that any future failures will be minor in scope, and it will have a projected life as long or longer than when it was first made. In my store I have my 1936 Philco 60 cathedral that I restored 4 years ago. It's a great conversation piece and so many people are amazed it works. It plays every day from when I get there about 9AM until I close about 4PM. Sometimes I forget to turn it off and it runs overnight or over a weekend. In four years, it only has needed an output tube.

The Andrea 16" TV I'm restoring will go in my front living room with my Radiola and 1850s Smith reed melodeon, and it will be with the expectation that I won't have to repair it except for maybe vacuum tubes at some point. I'll keep my fingers crossed that "hard" parts like the transformers, yoke, CRT etc. will live a long life.

I put the Andrea aside for now as I'm trying to build an exhauster and bellows for the Smith melodeon, but when I get back to restuffing the rest of the cans in the Andrea, I'll take some pictures and post what the cans look like when unrolled.

John

Here's what I found when I unrolled a cap from an RCA 630TS. Rotting aluminum and pinholes through the insulating layer. I've restuffed quite a few and often they look like this or worse.

https://live.staticflickr.com/65535/...204757b3_z.jpg

what cap #is that in the RCA 630TS, if I may ask? :o

Interesting and I have seen the same. Notice the foil is very thin and exposing the corroded outer layer you tore the foil.

My question is that if only on the outer exposed foil, the thin aluminum foil has degraded, how about inside? And why how would the minor corrosion materially affect operation if the dielectric maintains low leakage and the capacity remains unaffected?

I disconnected the input filter from the 721TS to measure leakage and capacity this morning. This is after "patient"reforming after the 73 year old capacitor which had not been used for 60 years. The leakage had actually dropped in the 45 hours use from 500uA to 100uA at 400v for the 80uF capacitor. At the high line voltage around here (123vac) the input voltage across this capacitor runs at about 330VDC. The rule of thumb absolute maximum leakage from two sources online suggest 1mA leakage for every 50uf for a 450v capacitor.

One thing I noticed is that the 60 Hz Power Factor is not as good as a new capacitor.

Anyhow here are some meter readings from this morning. The Sprague meter is on the 0.6mA full scale range and reads 0.1mA at the 400v on the VTVM.

Meanwhile try opening up that 630TS capacitor to see if the corrosion permeated the internals. Somehow I don't think it did. Otherwise, the capacitance would have been noticeably reduced.

I've disassembled New and old capacitors. New ones do NOT have pinholes or rot like bandersons picture illustrates.

I have seen plenty of old caps like bandersons picture that were rotten inside the foil roll.

Some of my color sets get that much use in a week some weeks. And those sets usually get around that much run time in a month.

My monochrome sets usually see fewer hours.

So tell me how that materially affect the operation of the capacitor? I am sure you know if you live in the north, your car can still show rust and still be fully operational.

My point is that you are not scientifically assessing the damage and whether it impairs the operation of the capacitor. I am now inclined to take an old capacitor (I have a parts 630TS with rusty chassis) send it through my reform school, confirm it first measures okay then dismantle it to have a closer examination.

Here's another from the 630TS. Different cap much deeper into the roll.

These caps showed as shorted in my vintage Solar tester.

I routinely test caps before opening them up. Ones that showed shorts or excessive leakage that would not reform often look like this.

I've had many that showed little leakage, but also very little capacitance. Gone open in other words. I see this more often than shorts.

https://live.staticflickr.com/3712/9...3ebfcbe9_z.jpg

By the look of it, it seems to be c224 RCA (C5 SAMS) or c220 RCA(c1 SAMS).

Okay, unwrapping a shorted capacitor or one that had failed I would expect the appearance you depicted! My point is if the capacitor reforms with low leakage and an even lower leakage is observed after 100 hours, the capacitor should have no problem in service for 1000 hours.

Again I am inclined to open a good capacitor of this vintage and not one that has failed. The key is that the leakage remains low over time.

And do you honestly intend to run your sets hundreds of hours?

Some of us do. I have a couple of color sets that I've used 3-50 hours a week every week for 6-8 years.

I really fail to see what the point of all this discussion / contention is all about.
When it has been shown over and over again, (and there are many sites dedicated to this. ) that in the restoration of vintage electronics, decades old capacitors, electrolytic and paper, are inherently unreliable due to entropic degradation, and even though they may seem to work, they are like a time bomb waiting to go off, and best replaced with more modern ones which are smaller, and often will preform better and last longer than what is being replaced, especially if high tolerance long life type is used, and of slightly higher voltage range than the original.
And, as it has been pointed out more than once, these new caps can be stuffed into cans of the old, leaving the visual aesthetics unaffected, or, as in the case of my CTC-16XL, I just unhooked the old caps on the bottom, and placed the new ones various places under the chassis, from the top, you can't tell anything was replaced, and I chose the new caps very carefully, all high tolerance long life, if replacing 80uf @ 450v, I put in a 500v one, 20uf @ 250v = 300v , and so on.

It's MY choice not to risk things on old caps, and I'm sure others feel the same, but if you want to run your stuff with them, go right ahead!:D:yes:

I think the bottom line here is this ;

old capacitors are kinda like old people , some live a perfectly healthy life well into their 90s and some begin to seriously degrade starting in their 60s and don't make 70 . And when those people were young there really was no telling which would see the near century mark VS who'd be worm food by 60 . I'm sure there are those caps that'll live to a ripe old age performing their capacitor duties just fine without missing a beat just as there are plenty of them that are right now going to crap in 5 year old TVs , all the while their antique counterparts are still happily doing the cap thing without a whimper . It's luck of the draw , nothing more , and while I think it's great that those particular caps reformed well and came back to life I don't believe every , or maybe even every other , antique cap can be revived in such manner . As a cool experiment I think it's great that you had success but with the destructive nature of a shorted Ecap in mind I do systematically replace every one in any "daily driver" sets I run , just so that I can feel somewhat comfortable leaving them to run while I do things in other parts of the house without having to keep a literal eye on them ;)

:thmbsp: I , for one , am hoping to see your experiment run well into the hundreds of hours .....

Entropic degradation? I am curious what this is.

I am amused bt your comment "when it is shown over and over again". There is a lot of stuff on the internet by many self proclaimed experts. You have not attempted to test the process and I see you are not willing to accept the evidence I has provided. The set has been on now continuously for over six hours reaching a total of 50 hours and the electrolytic capacitors remain fine.

I am not disputing anyone who chooses to replace the electrolytics. However I am disconcerted by reading here that all capacitors including electrolytic, paper and mica should be blindly replaced.

It is amusing to see defensive reaction to my hobby specific activities. I do not disagree with you if yo prefer to replace the capacitors. I have refilled many electrolytic cans myself, most recently my HP DC power supply. I am only posting this information here to demonstrate to all how the capacitors can survive more than seven decades and still work.

I am going to look inside a reformed good capacitor to see what degradation has occurred. I would also suggest you try reforming an old capacitor properly and then testing it for yourself.

I abhor the practise of applying power or even use of a Variac on a set that has not been thoroughly vetted and corrected. It is fraught with danger and because these electronic devices rely upon oscillators to generated grid bias, will lead to other component failures.

Note in this case, I reformed the capacitors and made all the required component replacements after detailed analysis of the circuit before applying full power. This set came up immediately and worked without issues.

I think you're assuming members of this forum haven't tried this. I won't speak for any other old timer here, but I have tried it as I mentioned in an earlier comment. What I discovered was that it was hit or miss, and therefore a waste of time when your name goes on a repair. Your example, although very interesting, won't change my experiences.

The Andrea I'm working on has a lot more hours than yours (I'd guess it's well over a hundred twenty five hours since February) and 5 of the cans are still good and operating fine, but history tells me that they're on bonus time. Using my own TV as an example, two cans were dead immediately, and two failed some 20-30 plus hours after it was running perfectly. The remaining 5 are still running fine at over a hundred hours. They're still coming out.

Sure, you can have capacitors work after 70 or more years, but proving a capacitor can work at 70 years and proving a capacitor can work for 15 hours a week for the next 10 years is another thing entirely.

I mentioned earlier that I'm restoring an 1850s reed organ melodeon. The leather exhauster is still working, but if don't replace the leather, how long will my wife be able to play the melodeon before the leather tears? 10 hours, 100 hours? Maybe she'll never put enough hours on it, but I'm replacing the leather anyway. Once this melodeon is finished, I don't want to ever take it apart again.

That's the point we're trying to make on this subject.

John

+1
I've also reformed and vetted lytics with my Heathkit and watched them fail after dozzens of hours of operation.

I've seen TVs and radios run on original caps and even keep a few that way as shelf queens that rarely get powered. Though even that isn't common since if I power on a display set and it dies on me it could be an embarrassment, and even if it isn't I rather feel confident I can grab anything off my shelf and run it as if I just bought it new without worry.

I put enough hours on my sets to go through certain tubes multiple times. Anything that will help put the next repair farther out into the future and let me tackle repairing something else or let me live my life away from the bench is worth doing.

I did mention I have a 1949 RCA 8T243 I acquired in 1970 and still runs on its original electrolytics. If I am fortunate to still be alive in 20 years, I will let you know if the capacitors are still okay.

And I generally do not watch 15 hours of TV. I the 721TS case, I simply left it running while going about other things.

I find it very amusing however how some members of this forum take the subject of electrolytic capacitor replacement so very seriously.

Well I have seen a bunch fail in service. And many have not passed the reforming process and test before putting into service. You have not explained what your criterion is. Instead you trash my observations.

And as as this to me is purely a hobby, if the component fails in service, it provides further enjoyment pulling the thing apart to service it because it is my hobby.

Maybe some of us should stop to reflect and chill out.

Thanks for the comment. I sort of see that as well: some have a grand old age and others sadly die prematurely.

I think the success for a long life, both in human and electrolytic terms is to recognize the symptoms of disease early and address it. Some prefer milder treatment whereas others go for radical treatment. And continuing the comparison no one know absolutely for sure if the remedy will be effective or not.

The set now appears very healthy and runs well after 50 hours in the last four days. No detectable hum, lots of clean audio and a sharp picture on my good 10BP4. And rechecking the leakage on one of the electrolytics,, it has dropped a further 80% in the last 50 hours.

Again this project is to satisfy my own personal interest in preserving as much originality in the 721TS as possible and should in no way dissuade you from replacing vintage electrolytics in your own equipment if you so desire. And if I were to leave the set unattended I would protect it by other means such as a fuse. But I am happy remain with the set while it is on.

I'll easily agree that with better than 50 hours on it and the leakage continuing to drop that those caps have proven themselves at least in the short term . I really am hoping you get 100s of hours out of them because it would further your experiment and show that at least some do survive long term . I saw in your first post that you live in Canada and the set was stored in an attic . I know nothing about the general climate where you live so I'll ask , do attics there get Hell like hot in the summer like they do in the lower States of the US or is the climate cool enough there that the set wasn't subject to regular temperatures over 100 degrees (F) ? If the attic remained cool year round I'd bet that one difference likely made a world of difference in the condition of the caps VS a set stored the same amount of time in a Texas attic .

I actually bought the set in central NY near Schenectady. The was no TV in Canada until 1952 and the first available TV dighna l here was from WBEN TV Buffalo NY in 1948. Muy RCA 8T243 was allegedly the first Canadian built TV manufactured in Montreal Quebec.

I bought the 721TS from the house it was purchased for and sat in for over 65 years. The attic was insulated so I guess it did not get too warm in the summer nor too cold in the winter. The set is interesting as it was quite dirty but typical he chassis was not corroded.

I bought an RCA 8T271 which included survivor electrolytics from a home just outside Philadelphia 7 years ago. The original owner bought the set just after he left the US Army with a bonus and he retained it until his death at the age of 91 in 2013. His family sold it to me and despite it not working and sitting in a corner in ther house for nearly 60 years unused, the electrolytic capacitors all came back fine and are still okay after hundreds of hours. This set, having sat indoors its whole life, had a pristine chassis. It looks like new.

So you have to take each case as it comes, I guess.

The 721TS is currently running and has reached 52 hours. Running some Popeye cartoons.

I grabbed a couple of electrolytics from a rusty old Fada 630TS chassis (cabinet dissolved into shards). Looks like it was stored in a wet shed outside. So the electrolytic will have suffered wide climatic changes.

I started reforming it at 4pm today. It is now 10:30pm and at 450 volts the 10uF and 40uF capacitors in the can connected in parallel show a leakage of 200uA. This shows the capacitor is good. The 40uF measures 45uF and the 10uF measures 15uF.

I have been told I am lucky. Maybe so but I never have won a contest or even a book at the local raffle. So this baffles me why I have so much success and everyone else has horror stories to relate.

With the reformed electrolytic with such low leakage at full capacitor rated voltage, before tearing it apart, I would like to leave it at the full 450 volts for a day to see what happens. I maybe will after over voltage by say 5% to see what happens. Fortunately the failure mode is predictable: when it starts to go, like the paper capacitors, there will be a thermal runaway where the leakage increases creatingvheat which further accelerates the leakage and so on. In a paper capacitor, there is little thermal lag so the paper capacitor thermal runaway is fairly fast. The larger electrolytic thermal runaway is slower and more manageable.

Here is a picture of the reformed 630TS capacitor. Notice the VTVM reads 450 Volts DC and the Sprague TO-6 reads 200uA on the 0.6 mA full scale range. And a picture off the 721TS on the weak 10BP4.