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 Post subject: What's the oldest working filter capacitor that you've seen?
PostPosted: Aug Wed 07, 2019 12:07 am 
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I have 4 Zenith tube radios with working original filter capacitors, all from the early to late 1950's. Is it just my luck? Is it the quote on quote "Zenith Quality"? Maybe. But what's the oldest original filter capacitor that you've still seen working?


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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Wed 07, 2019 12:21 am 
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I too have had good luck with postwar Zeniths filter caps not humming. But I replaced them anyway. Nothing prewar comes to mind of any brand.

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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Wed 07, 2019 12:31 am 
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That depends on the context of "filter capacitor"

Many filters from the late 1920s and very early 30s were paper capacitors installed into metal boxes and potted in tar.
many of these early caps have survived and still function normally.

However, i believe you may be referring to the oldest electrolytic filter capacitors still functioning?

Well, I bought a 1934 Zenith 775 last year. When I went to pick it up, the seller had it playing to show me it worked. As he said he was a TV repairman, i assumed he had recapped it.
I got it home and discovered it is almost 100% original underneath! Yes, it had a slight amount of hum, but nothing objectionable and it was playing very well!

Just unbelievable! I am amazed those original electrolytics from 1933/34 were functioning! :shock:

-Steve


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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Wed 07, 2019 1:05 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Phoenix, Arizona
I have a Radiola 60 with its original filter caps, works hum free. My 1936 McMurdo Silver M-5 has some of the original type , if not original liquid filkled big tall metal can type. in the audio / power supply chassis. I have a 1948 Scott 6T11 TV that has all its original filter caps and works fine. Some of the paper caps have failed however.

Jim


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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Wed 07, 2019 2:23 am 
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Location: Grantham, New Hampshire
I have a Victor VE 10-70 with all original filter capacitors and resistors from 1927. Have played it for long periods of time a few or more times a week for over 20 years. I think I have played it more than the original owner. If those old paper capacitors are not leaky they will last for a long long time.


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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Wed 07, 2019 2:35 am 
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It all depends on the materials used in construction. With electrolytic capacitors, the integrity of the seal is critical; if the electrolyte dries out, and corrosion sets in, the capacitor becomes open. The familiar box and tubular electrolytic capacitors found In AC-DC radios are usually found open or leaky for that reason.

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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Wed 07, 2019 10:56 am 
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Tim Tress wrote:
It all depends on the materials used in construction. With electrolytic capacitors, the integrity of the seal is critical; if the electrolyte dries out, and corrosion sets in, the capacitor becomes open. The familiar box and tubular electrolytic capacitors found In AC-DC radios are usually found open or leaky for that reason.

+1, and I'll add that how and where the unit was stored all these years can also have a profound effect not just on electrolytics, but most of the other components as well. Also, how many hours it was used during its lifetime can also have a profound effect on the condition of the components.

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Last edited by Barry H Bennett on Aug Wed 07, 2019 2:14 pm, edited 1 time in total.

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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Wed 07, 2019 1:58 pm 
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I will point out the Radiola 60 and VE10-70 all use paper capacitors potted in boxes for the filters.

The chances of them still working is pretty good if they haven't been exposed to excessive moisture.

-Steve

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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Wed 07, 2019 3:24 pm 
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Steve, I read somewhere that they used better quality paper in those days. Evidently, Atwater Kent used cheaper paper in his caps, which is why so many 40 series power supplies need work.

That picture of the Zenith chassis is amazing; I would be tempted to leave it unrestored!

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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Wed 07, 2019 3:51 pm 
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Thank Tim, I probably will leave it as is. Well, the only thing not original is the line cord, I may put a cloth one on it.
But, its probably going to remain untouched.

I have enough projects anyway. Its not high on the list :wink:

-Steve

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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Wed 07, 2019 4:22 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Phoenix, Arizona
I own a 1922 Ford Model T which has it's four original ignition coils which contain a capacitor each.

These coils have never been apart and I have had custody of the car since 1965.

Jim


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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Wed 07, 2019 7:58 pm 
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jimmc wrote:
I own a 1922 Ford Model T which has it's four original ignition coils which contain a capacitor each.

These coils have never been apart and I have had custody of the car since 1965.

Jim
Did Ford model T ignition coils have paper dielectric capacitors or did they use glass plates?


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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Wed 07, 2019 8:09 pm 
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jimmc wrote:
I own a 1922 Ford Model T which has it's four original ignition coils which contain a capacitor each.
These coils have never been apart and I have had custody of the car since 1965.
Jim
Those are buffer caps. If they are leaking, in time, there will be metal transfer of the contacts on the vibrators. Since they are potted in tar in a "Salt Cod Box" no trivial matter to get at... A consideration if one is constantly burnishing the contacts. Ford or aftermarket made a coil evaluator...

Chas

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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Wed 07, 2019 10:09 pm 
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Location: Long Island
I have a Detrola ca. 1937 AC/DC table radio which still works and plays well on its original cardboard box "dry electrolytic." It also still has most of its original wax paper capacitors which also still work; only one was replaced with a Black Beauty many years ago. Some of the tubes were changed so the radio must've been used and serviced from time to time.

I've got plenty of other radios to listen to, so I intend to keep this one as it is and not turn it on very much! It's a rare example of the law of averages (which predicts that the majority of any group or class of things will last an average amount of time, a few will fail right away, and a few others will last indefinitely) in operation.

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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Wed 07, 2019 11:36 pm 
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I have had this Stromberg Carlson for about 35 years, it is in the basement next to my workbench. All the capacitors and resistors are original, plays great. The power cord and grill cloth have been replaced. It is very heavy!! The chassis is copper or at least copper coated.


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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Wed 07, 2019 11:43 pm 
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AWESOME cabinet... who cares what radio is inside !!

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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Thu 08, 2019 1:31 am 
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I have a Radiola 18 from ~ 1927-1928. It still has all original capacitors (condensers) and plays well.

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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Thu 08, 2019 3:56 am 
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Location: Pennsville, NJ 08070
For me it’s a 1953 Westinghouse H-378T5. This set has an oddball plastic chassis and all ceramic disc caps except for two conventional paper/foil caps and an under chassis cardboard tube electrolytic.

To my amazement, the original electrolytic has absolutely zero hum. I changed the two paper caps and as an experiment, elected to leave that electrolytic in circuit to see how long it lasts. So far it’s been almost a year of multi hour use every few weeks and it still has zero hum, even with an ear up against the speaker. Either it holds the longevity record for such a device from that time period or it was re-stuffed by a previous owner so well there’s no evidence of it not being what I believe it to be...a factory original part...


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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Thu 08, 2019 6:05 am 
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Joined: Dec Thu 10, 2015 7:01 pm
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Location: Aurora, IL
My leader also happens to be a Zenith. Model H725 made in 1951 and still working well with original electrolytic. In fact.. the only thing I've done to it was to restring the dial cord after I brought it home. "Can't tune" was listed as wrong with it at the antique store I purchased it. Since it worked so well for fun I just let it roll and continued to play it.. became and still is a weekly user on my bench. Oh, and I've been playing it for over 10 years now with no problems or change in performance.
Must have been born with good radio genetics, huh?


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 Post subject: Re: What's the oldest working filter capacitor that you've s
PostPosted: Aug Wed 14, 2019 3:52 am 
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Joined: Nov Wed 04, 2015 4:04 am
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Location: Winfield, MO
Atwater Kent 55C for me. Aside from a dial lamp bulb, it seems to be all original and works great. Unfortunately the previous owner's cat shredded the grill cloth.


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