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 Post subject: The worst paper capacitor manufacturer?
PostPosted: Sep Sat 25, 2021 4:49 am 
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Of course, we know today that they all need to be replaced without question. But I'm wondering what brands tended to last the shortest amount of time?

In my experience, Micamold paper capacitors were the worst. Others worth "honorable" mention; Zenith-branded caps, Tobe, and the Sprague Black Beauty caps that liked to explode shrapnel all over the inside of a radio. The best (if you want to call it that) was the Solar Sealtite capacitors---for whatever reason, they tended to hold up longer.

But what has been your experience? I'm especially interested to hear from guys that worked on this stuff when it was fairly new

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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Sat 25, 2021 5:27 am 
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I agree, Solar Sealtite lasted the longest. There is also Sprague Vitamin Q but they are in a different league.

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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Sat 25, 2021 8:03 am 
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Nashville, as used in the Regency TR-1 and TR-1G. Now in fairness, they may have been a new miniaturized version for the newfangled Transistor radios, but nevertheless I've seen where they didn't last 5 years before needing replacement. With only having to handle 22.5 volts at miniscule current, one would think they certainly should have held up much longer.


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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Sat 25, 2021 12:06 pm 
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fifties wrote:
Nashville, as used in the Regency TR-1 and TR-1G. Now in fairness, they may have been a new miniaturized version for the newfangled Transistor radios, but nevertheless I've seen where they didn't last 5 years before needing replacement. With only having to handle 22.5 volts at miniscule current, one would think they certainly should have held up much longer.

Allied Radio Knight-kit used the Nashville brand and they went south often. Callins was another infamous brand at times.

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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Sat 25, 2021 6:26 pm 
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Interesting that those caps would be so leaky with such a low voltage being applied to them

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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Sat 25, 2021 7:48 pm 
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Nashville and Callins were mostly if not all electrolytics, not paper caps. And while they had excellent specs when new, most didn’t make it much beyond five years before they began degrading. Likewise, Micamold paper caps were rocket science when they were made, those were the caps we fought WW-2 with. But they were only designed for 10 year service lives so nearly all are dead now, 80 to 90 years after they were made.

My vote for the worst paper caps is Gudeman. They were a small outfit that existed for a while in the late 40s and early 50s. You see them in some test instruments and Emerson radios. Have not found one yet that isn’t practically a dead short today—or was 50 years ago when I first started working on stuff.

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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Sat 25, 2021 7:56 pm 
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I've seen Gudeman in a few different brands of radios (the last ones being in a pair of RCA 56X2's), but I noticed that there would only be 1 or 2 in each radio. And yeah, they were always leaky

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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Sat 25, 2021 8:03 pm 
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Almost every Solar capacitor I pulled from 1940s radios ... still measured good... capacitance wise and were working well before removal

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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Sat 25, 2021 9:25 pm 
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fifties wrote:
Nashville, as used in the Regency TR-1 and TR-1G. Now in fairness, they may have been a new miniaturized version for the newfangled Transistor radios, but nevertheless I've seen where they didn't last 5 years before needing replacement. With only having to handle 22.5 volts at miniscule current, one would think they certainly should have held up much longer.


In almost all my Zenith radios they seem to use a lot of the Nashville's. I normally just replace them unless the radio is still working well and I want to keep it as original as possible. I will need to start checking out the mica caps. I have also started to test the new caps I am putting in. I have found one bad one I purchased from an electronic supply house. Threw me for a loop on that radio for a while . It was a NTE cap.
In looking at your radio I see alkaline batteries in it. I also use them but have come across a couple of articles that suggest standard batteries due to the current flow. In the Zenith Royal 500s it has two diagrams for batteries. One is for mercury batteries and one is for standard batteries The placement of the battery position is different for each. Should the alkaline batteries be positioned as mercury batteries ?? What are mercury batteries ??


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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Sun 26, 2021 12:46 am 
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Solar had an interesting history. NYC company that began making dry electrolytic capacitors around 1935, moved to Bayonne NJ and got very big on electrolytics, paper, and mica capacitors. Their tubular wax paper caps were good, but about the same as Sprague, Aerovox, CD, and the like. They also produced a line of capacitor testers which were very good for their day. Around 1940 they came out with "Sealdtite" capacitors which had molded plastic cases around the paper slugs. Apparently they had to use a special oil to impregnate the paper which preserved it, rather than caused it to deteriorate as in normal paper capacitors. Sealdtites were about the lowest leakage, highest reliability tubular paper capacitors ever made.

The company grew rich on military contracts during WW-2 but in a misguided move decided to purchase a huge plant in Chicago to expand, right before the war ended and their contracts got canceled. Stuck with huge mortgage payments on the new building and no income while the economy shifted back to peacetime production, Solar went bankrupt in 1947 and the court appointed administrators to run the company. They cut quality and laid off most of the engineering staff which predictably destroyed the brand and forced a final liquidation of the assets. After the original Solar company was broken up, the Solar name was apparently picked up by a successor company which used a different logo. They made replacement grade dry electrolytics for AA-5 radios and similar products. They seemed to be popular long ago but I have not come across any which are still good today.

Among the assets sold in the liquidation of the original company were the patents on Sealdtite capacitors. They were purchased by Sprague which was then developing its line of "bumblebee" capacitors. I do not know if they used any of Solar's technology in the "bumblebee" caps or if they were similar enough that Sprague felt compelled to buy the patents to head off any infringement suits, but it is interesting to think that we might still be using paper capacitors today if they had decided to further develop Sealdtites instead of bumblebees. In my opinion bumblebees were no better than Micamold caps when it came to longevity.

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In looking at your radio I see alkaline batteries in it. I also use them but have come across a couple of articles that suggest standard batteries due to the current flow. In the Zenith Royal 500s it has two diagrams for batteries. One is for mercury batteries and one is for standard batteries The placement of the battery position is different for each. Should the alkaline batteries be positioned as mercury batteries ?? What are mercury batteries ??


Mercury batteries were a development of Paul R. Mallory (yes, the capacitor and Duracell Mallory). They were non-rechargeable dry cells which had fundamentally different characteristics than carbon-zinc types. Their shelf life was about 10 years, and their terminal voltages remained within 1% of 1.35 volts per cell for about 95% of their lives. After WW-2 they became popular for things like cameras and photographic light meters, hearing aids, test instruments, radios, smoke detectors, and many other electronic devices. The problem was, when they were exhausted they got tossed out with the trash, where it was feared the toxic mercury would leach out into landfills and ocean dumping sites. They were gradually phased out then entirely banned in most countries by 1991.

The button or tip of a mercury flashlight battery was the negative terminal, which is opposite that of a carbon or alkaline cell where the button is positive. Many transistor radios of the late 1950s have two battery diagrams showing how carbon and mercury cells should be arranged, since a customer might use either type. If using alkaline cells, follow the diagram for carbon zinc batteries, otherwise you'll reverse the polarity which could damage the radio.

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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Sun 26, 2021 1:03 am 
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Say what you will about the Callins electrolytics, but in most all the Zenith transistor radios I've recapped, those are the ones that still work. Not saying the values aren't off, they are, but they still work often with good volume. It's the Nashville and other "white" caps that are always bad. What I can't understand is when a radio still plays when a cap reads nf instead of uf! Hard to believe some only lasted 5 years!


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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Sun 26, 2021 1:22 am 
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Hello everyone,
I know this is a little off the subject but it can apply to those who restuff aluminum can electrolytics.
What other bad chemicals are on old electronics? Did oil filled paper caps contain poly chlorinated biphenyls (PCB)? what about electrolytics and transformers. When an aluminum can electrolytic is restuffed does it expose the person to PCBs. Wax caps I think are safe. Cloth wire contains asbestos on the inside and what I do is coat them with clear nail polish and it encapsulates the brittle insulation from coming off and because it's clear you can still see the color codes. If you want to replace all the wires with re issue original cloth I recommend coating the old ones first for safety to prevent the fibers from breaking off into the air. I'm 58 and plan on doing restorations for a long time still


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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Sun 26, 2021 2:39 am 
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Chriscrosley1 wrote:
Hello everyone,
I know this is a little off the subject but it can apply to those who restuff aluminum can electrolytics.
What other bad chemicals are on old electronics? Did oil filled paper caps contain poly chlorinated biphenyls (PCB)? what about electrolytics and transformers. When an aluminum can electrolytic is re-stuffed does it expose the person to PCBs. Wax caps I think are safe. Cloth wire contains asbestos on the inside and what I do is coat them with clear nail polish and it encapsulates the brittle insulation from coming off and because it's clear you can still see the color codes. If you want to replace all the wires with re issue original cloth I recommend coating the old ones first for safety to prevent the fibers from breaking off into the air. I'm 58 and plan on doing restorations for a long time still
The dangers of chemical exposure when working with expired electrical devices depend largely from where the device came from.

PCB insulating oil is more costly than waxes or mineral oil. To keep costs low and remain competitive such materials would not be found in a domestic household product. Therefore, capacitors from military, or industrial devices especially if the device is expected to have high reliability will likely contain PCB before 1976. Many of these devices had trade names for the PCB or derivative insulating oils inside. These names can be found in lists online.

Asbestos can be found in not only radios but things like electric irons, electric hot plates (cords), electrical lighting fixtures, electric ranges, soldering irons, old). Modern appliances now use a ceramic or fiberglass insulation. Fiberglass is a danger too.

Textile covered wire used in radios does not contain asbestos. One exception is in early RCA SPU's that get hot from the dropping resistors, used asbestos covered wire. other old wire is cotton or jute fibers over extruded rubber, the wire is then either continuous cured or batch cured. Rubber is a difficult material to cure properly either over or under a small margin of sulfur with either cause the insulation to melt with time or cure continues until it becomes hard...

PVC has it dangers too, vinyl chloride is a dangerous gas released when the plastic chemistry is overheated. Heat failures of PVC covered wire are regularly found in modern applies, usually at the terminals. The electric arc releases HF a dangerous gas. Cleaning chemistry can release chlorine, propellants in canned service chemicals can either breakdown in heat or flame or explode. Copper when exploded from an electric arc expands enormously.

If one treats all devices with respect as having a danger, like lead solder for instance. Then normal precautions should keep you repairing well into your 90's.

Wash hands, wear the PPG, do not eat smoke or prepare food in the repair area. For some this is the dining room table :roll:

You could still do all that and get a fatal electrical shock :roll:

All this learning proves too daunting, have someone else do the work for you off site.

I haven't lost any sleep or brain cells in doing electrical repairs for more the 65 years. I know my enemy... :twisted:

Dispensing fear of the unknown does a dis-service. Be informed and be well...

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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Sun 26, 2021 3:10 am 
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Thank you Chad I am impressed. You are very intelligent and have much experience. I feel safer


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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Sun 26, 2021 3:28 am 
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Absolutely nothing in electronics--antique or modern--is good to eat, breathe, or get on your skin.

Yes some capacitors used in electronics contained PCB oil. There are lists online of manufacturers and brand names to watch out for. But oil capacitors were rarely used in consumer electronics, and the sizes contained in most military and industrial surplus, and commercial equipment had very little oil in them, and most of what they had was soaked in paper separators. Indeed the amount of oil usually encountered in electronic capacitors is so small the EPA doesn't even classify small quantities of them as hazardous waste. PCB oil is neither toxic nor carcinogenic in the amounts you'd be exposed to by a leak from a small capacitor, but PCB or not, any oil that comes from a capacitor is probably a skin irritant so you do want to clean any leakage up well and not get it on yourself or your fingers.

Electrolytic capacitors are made of aluminum with rubber or plastic seals. Inside there is an electolyte solution or paste which often contains anti-corrosion agents and other proprietary additives. Water based and glycol based electrolytes were and still are used. Take the same precautions with these as you would with automotive radiator chemicals. Many are slightly acidic and will sting sensitive skin; in that case flush with water.

Don't know where you came up with the idea that all cloth covered wire contains asbestos. It doesn't. They had to pay extra for the asbestos so it was not used where it was not needed. You'll find asbestos in some cloth covered AC line cords where it provided additional protection for the rubber insulation on the wires in case the cord came into contact with hot surfaces, but it was not used in the ordinary cloth covered wire used for chassis wiring. Resistance cords used in lieu of ballasts in AC/DC radios often contain asbestos insulation around the resistance wire for obvious reasons.

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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Sun 26, 2021 4:40 am 
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tomb123 wrote:
In looking at your radio I see alkaline batteries in it. I also use them but have come across a couple of articles that suggest standard batteries due to the current flow.

I've never seen any difference between using carbon zinc or Alkaline in the performance of a radio. Simply that the latter lasts longer.

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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Mon 27, 2021 3:24 am 
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The line cords (2 wire, not the resistance kind) that had asbestos were found on heating appliances, soldering irons, toasters, clothes irons, and things like that. They generally had a black woven cover over the asbestos usually with colored stripes or threads in it. They're easy to spot.

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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Mon 27, 2021 12:58 pm 
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Pbpix wrote:
Almost every Solar capacitor I pulled from 1940s radios ... still measured good... capacitance wise and were working well before removal

They were used on a lot of EH Scott Philharmonic amplifiers. Everyone I have pulled had no leakage at full rated voltage. Is there really paper in there?, lol. I still have a pair on my bench from the last amp I did and might open one up to see what they did differently.

I found a lot of leaky Budroc capacitors in my 1950's New London 901A, yet another guy had the same capacitors in a 50's radio recently and told me that every one tested good. I don't know....


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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Mon 27, 2021 1:52 pm 
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I have to agree about the Callins and IEI electrolytic capacitors; another stinker is the red "Tiny Chief" molded capacitor, used heavily by Seeburg and DuKane in the 1950s. Ditto on the Budroc and John Fast caps from the same era.

I have also encountered the Solar caps with no leakage; they did something right!

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 Post subject: Re: The worst paper capacitor manufacturer?
PostPosted: Sep Mon 27, 2021 5:09 pm 
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All of the above, ^^

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