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Need some help with capacitors on a schematic.

MaxHeadRoom78

Well-Known Member
I assume you are refering to the distinction between electrolytic and the smaller value decoupling paper/foil types etc,
The latter uses a ground side symbol or arc to denote the outer foil of the capacitor in order for it to be connected with the outer foil close to GND or chassis.
 
I assume you are refering to the distinction between electrolytic and the smaller value decoupling paper/foil types etc,
The latter uses a ground side symbol or arc to denote the outer foil of the capacitor in order for it to be connected with the outer foil close to GND or chassis.
So the paper caps aren't polarized right? Also I found a cap that says "dry electrolytic capacitor". Should I replace it, do the dry ones go bad as often as the regular electrolytics?
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
So the paper caps aren't polarized right? Also I found a cap that says "dry electrolytic capacitor". Should I replace it, do the dry ones go bad as often as the regular electrolytics?
In the circuit, the outer foil needs to go toward the lowest Impeadance source. They were marked that way. See the you tube channel Mr. carsons lab for his identifying device on modern capacitors.

To get the schematic you have to join his patreon page,

i would suspect that if you had a plugged in power transformer and connected a scope probes to the capacitor and moved it near the transformer. One way it would pick up more 60 Hz than the other. That would be the outer foil, I believe. You can always rip one apart to be sure. Do not belive the markings on modern capacitors.
 

MaxHeadRoom78

Well-Known Member
So the paper caps aren't polarized right? Also I found a cap that says "dry electrolytic capacitor". Should I replace it, do the dry ones go bad as often as the regular electrolytics?
Not polarized electrically, but just for physically mounting purposes to indicate which cap connection is connected to the outer foil.
If the dry electrolytic appears OK I would leave it in place.
 
Not polarized electrically, but just for physically mounting purposes to indicate which cap connection is connected to the outer foil.
If the dry electrolytic appears OK I would leave it in place.
So, I could just replace it with a standard non polarized ceramic or film capacitor right?
 

Nigel Goodwin

Super Moderator
Most Helpful Member
So, I could just replace it with a standard non polarized ceramic or film capacitor right?
Yes, if they need replacing - are they faulty?, there seems little reason to replace capacitors if there's nothing wrong with them.

Historically a classic fault in valve was leaky coupling capacitors, usually feeding from anode of one valve to the grid of the next, producing a positive bias and messing things up. The usual culprits were capacitors made by Wima, and they were well worth blanket changing as if they weren't faulty at that moment, they probably would be next week.

If something came in for repair with an electrical fault, it was standard practice to replace any Wima caps, and then worry if it wasn't cured.
 

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