Be careful what type of capacitor you use!

[Eric H]

Or you could cause yourself more problems.

I finally got back into finishing up an RCA 8-TK-320 that I started working on about 10 years ago.

The set was working well but there were a dozen or so caps I still hadn't changed, one of them was a large .22 Micamold in a flat rectangular case, it's function is Horiz AFC filter.

I had some misgivings about replacing it with a plain yellow Poly cap, I had a felling RCA must have used an oddball type for a reason.

After finishing up and turning the set on I noticed that the upright lines in the picture were more than a little wavy, I hadn't noticed them being like that before, normally I hate problems like this but since I was leery of that one cap to start with I went back and put the old one in, Viola, problem gone!

Lesson learned, any cap that isn't a plain paper type is probably there for a reason, maybe this really is a Mica cap but it's pretty large at .22 mf.

Now, how does one go about finding out exactly what they have and what to use in it's place, or if it should be left alone?

Sams gives replacement part numbers for Cornell Dublier Aerovox etc, so I suppose if you had a catalog you could look up the specs.

[willyrover]

If you put the old one back and the problem went away, why replace it? Unless it's an electrolytic or way out of spec, I'd leave it alone.

[Eric H]

That's what I did, the 60 year old Micamold works fine, for now at least.

[jeyurkon]

If I read the color code correctly, that's a 0.022uF mica capacitor. Those are available. Assuming that I'm right, that might also account for the problem you had with the film. I think the mica are better at HF though.

The Sams for my Sylvania has several mistakes in it. I'd trust the value of what's in the set before I'd trust Sams. In my case I'm sure it's a mistake and not a production change because the part list differs from the schematic. I also have all the production changes that Sylvania published.

John

[Findm-Keepm]

Originally Posted by jeyurkon

I'd trust the value of what's in the set before I'd trust Sams.
John

Wholeheartedly agree. Sams are famous for their mistakes and omissions. They corrected errors by publishing error notices in subsequent Sams sets, and only those that went to Photofact-of-the-Month subscribers, and later, their PF Reporter magazine. That said, I wouldn't sell or trade my Sams (sets 17-2016) for anything in the world. Just too invaluable!

Cheers,

[Eric H]

You're right, it's a .022 according to the code, I never looked beyond the two red dots and I must have mixed up C90 and C91 on the Sams photo.

The one under it is the .22 so perhaps using the wrong value is what caused the problem and not the type of cap.

In any case I'm not changing it again, it's in there and there it'll stay, unless it shorts or something.

I'll post some pics of the set later, it has one of the sharpest pictures I've seen on a 40's set, the 16AP4 is NOS from 1950.

[jeyurkon]

Originally Posted by Findm-Keepm

Wholeheartedly agree. Sams are famous for their mistakes and omissions. They corrected errors by publishing error notices in subsequent Sams sets, and only those that went to Photofact-of-the-Month subscribers, and later, their PF Reporter magazine. That said, I wouldn't sell or trade my Sams (sets 17-2016) for anything in the world. Just too invaluable!

Cheers,

And I keep hoping to find someone about to dump them as they retire their business. They are very useful.

John

[Findm-Keepm]

Originally Posted by jeyurkon

And I keep hoping to find someone about to dump them as they retire their business. They are very useful.

John

Exactly how I got mine - when my father retired, I got his early Sams, and he sold the newer stuff to another shop for pennies on the dollar.

Keep checking with the shops in your area - Dad gave away numerous duplicates he had accumulated over the years. His earliest stuff came from a estate where the guy was working out of his house, on a hobby basis. Occasionally, an entire collection will appear on eBay, for local pickup only - that could be another way to get them inexpensively.

Cheers,

[Bill Cahill]

That particular cap is not paper. It is mica. Unusual for such a high value in mica, but, not un heard of.
RCA, and, Zenith were good for those types of tricks.
Mica mold paper caps have the value written on. No dots.
I have had paper mica molds explde.
RCA used those in an early three tube 45 rpm player. Before I realized what was happenning, and, this was 23 years ago, I was getting distorted sound, a bad odor, and, smoke.
Un plugged it, and, took it apart after I heard a loud pop.
Two mica mold paper caps had exploded.
Bill Cahill