Understanding Capacitor Markings in Old Tube Radio Restoration - Decipher Their Values

Question

Hello.
I started overhauling my old tube radio.
The first step after cleaning the top layer of dust, the first thing I want to do is replace all the capacitors. However, there was a problem with their markings. Below I paste photos of capacitors that I have doubts about.
Please explain these signs and how to read them in the future.

Piotr2608 · Answer

As well I remember, if not someone to correct me: 200i - 20pF 1600V 0.01J - 1nF 250V 820H - 82pF 2.5% tolerance 200J - 20pF 5% tolerance 5600J - 560pF 5% tolerance 50/12 - ??? 3300 - 330pF 1600V

scotch · Answer

So for the future: Uncle Google and topic: capacitor markings and an example Colorado beetle is:

abart64 · Answer

I guess the old ones were marked directly. 200 is 200p, 820 is 820p. I do not associate any with the designation, for example 331. 50/12 is 50u 12V

_jta_ · Answer

767 Miflex in the third photo - unfortunately only the climatic category is visible. 2/70 - 2uF / 70V electrolyte. The letter H or J is accuracy - this is in the second link in # 3.

I think, however, that the markings contain capacitances in uF (0.01 = 10nF), or in pF - that's what I read, according to this I took into systems and these systems worked as predicted. The fashion for marking, where the last digit gives the power of 10, used to only apply to barcodes of resistors, and moved to capacitors when they were SMD.

zetdeel · Answer

From what you've shown, there are only two electrolytes to replace: 50uF / 15V and 2uF / 70V. The others are styroflex capacitors, characterized by picofarads. If they are operational - do not move! This also applies to the ceramic lollipop 3300pf / 500V.

FireEnd · Answer

Even in 55-year-old equipment, do not touch the styroflexes? Maybe they will last a few more years, but the paper ones need to be replaced?

398216 Usunięty · Answer

They will outlive us all for sure. These potatoes must be replaced immediately.

_jta_ · Answer

The paper ones have a dielectric made of oil-saturated paper - and at least for a while it was oil that evaporated after a long time (decades) if the capacitor was not tightly closed - and this reduced the capacitance of the capacitor and could also lower the breakdown voltage. This paper is brown in color, similar to typical kraft paper. Once, someone from my extended family showed me the Wisła TV set - one of the first Polish TV sets - still functional, but after replacing the paper capacitors.

FireEnd · Answer

Well, I am replacing the potatoes, but ... Can anyone tell me what's going on with those with three leads? Was it shielding? If so, how do you check which derivation is which?

398216 Usunięty · Answer

Picture not very clear ...
The mass was not marked as far as I know. There is a black strip on the casing - it means an electrode connected to the outer lining - which (in some cases is important) as a screen.
Check with a meter that there is no connection between these wires on one side.
And by the way - what is this equipment? And what is the marking of this capacitor?

FireEnd · Answer

In the diagram it looked like shielding, and indeed one lead of the capacitor was connected to ground. Dismantling the capacitor revealed that it was a piece of aluminum foil shielding the capacitor. I put on wims, ignoring the shielding. In case of increased interference, I will do some research. The capacitor was 22nF 400V.
The receiver is a diora sonata 22002.

Understanding Capacitor Markings in Old Tube Radio Restoration - Decipher Their Values

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