Capacitor question

[radio nut]

One of the web sites that sells caps says that the round yellow caps work better in AC circuits and the orange ones do better in DC . When I am working on a 55 year old tv does it really matter? Aren't the new caps far better than the old? And If they are correct what about my last set which had 330 volts AC and 90 volts DC on the same line in the Horiz.,then what?

[marty59]

I wouldn't agree to that. A capacitor blocks DC and passes AC. Think of coupling capacitors as they are exposed to both characteristics!
Others will chime in I'm sure but most of the time it is a personal preference in "most" cases.

[jeyurkon]

Could you give us a link? It doesn't make sense to me either. The red ones could be either polypropylene or polyester. Polypropylene would be better at higher frequencies. But it also depends on how they are made. Both are supposedly non-inductively wound.

John

[radio nut]

Originally Posted by jeyurkon

Could you give us a link? It doesn't make sense to me either. The red ones could be either polypropylene or polyester. Polypropylene would be better at higher frequencies. But it also depends on how they are made. Both are supposedly non-inductively wound.

John

It was antique electronic supply in one of their catalogs I used to have. I have not checked their web site at all. The address is tubesandmore.com. Maybe I read something wrong.

[jeyurkon]

Originally Posted by radio nut

It was antique electronic supply in one of their catalogs I used to have. I have not checked their web site at all. The address is tubesandmore.com. Maybe I read something wrong.

I don't see anything in their current catalog to that effect. They do cater to audiophiles so it wouldn't surprise me if they had said something like that. Maybe when they talked about the yellow ones they were referring to the Auricaps.

The classic orange drops are good, but like Eric says, they're more difficult to use because of the radial leads.

John

[tubesrule]

Both the axial yellow and radial orange caps are available in polyester and polypropylene types. Polyester is a general purpose type while polypropylene is used in higher current pulse applications. The polypropylene types will be slightly larger, usually have thicker leads and cost more. There is really no reason for them in a television application as the polyester types are far superior to the original paper caps. Even in pulse circuits like the horizontal output, they used paper caps originally, so polyesters will work fine.

Darryl

[Tubejunke]

Originally Posted by marty59

I wouldn't agree to that. A capacitor blocks DC and passes AC.

Actually, a capacitor only appears to pass AC voltages. Internally there are two plates separated by a dielectric (insulator). So by the nature of its design can't pass any voltage. It can however store a voltage. There is a long winded electical/mathmatical explanation for this if anyone cares to look into the nature of alternating current and capacitance.

[marty59]

Originally Posted by Tubejunke

Actually, a capacitor only appears to pass AC voltages. Internally there are two plates separated by a dielectric (insulator). So by the nature of its design can't pass any voltage. It can however store a voltage. There is a long winded electical/mathmatical explanation for this if anyone cares to look into the nature of alternating current and capacitance.

Right. I just didn't get into that part!

[Eric H]

I use the yellow caps sold by Justradios and never had a problem.
By orange ones I assume they mean Sprague Orange Drops?

The Orange Drops are designed for PC board use and are a bit of a pain to install under chassis sometimes, the leads are stiff on them too, the yellow ones are much easier to use.

[old_tv_nut]

Some types are preferred for large pulse duty, like horizontal sweep circuits, but right now I can't remember which that is.

[jr_tech]

How about the "ceramic disk caps" ? have these pretty much fallen out of favor with radio/tv restorers?

jr

[jeyurkon]

Originally Posted by jr_tech

How about the "ceramic disk caps" ? have these pretty much fallen out of favor with radio/tv restorers?

jr

I use them where they were used originally. But they seldom fail. They probably shouldn't be used in sweep sections because of their voltage dependant capacitance.

John

[M3-SRT8]

I always replace like with like.

Replace Paper Tubulars with good (630 volt) polyester or polypropylene yellow Tubulars, Micas with New Micas, Disc Ceramics with Disc Ceramics, etc. Keep the replacements at or above the origional voltage rating for extra protection, and you're doing the Chassis a favor.

I habitually restuff Paper Tubulars with new ones, and replace them. Then, you keep the origionality of the Chassis, and know that your replacements are far better than the old 200 volt, etc paper ones.