Physical Electrolytic Cap Size Question

Thread Starter

John Czerwinski

Joined Jun 19, 2017
62
The polite way to make changes after someone has already responded to your post and referenced the text in question is to leave the original text with strike through and to note that it was edited. Not doing that makes the people who responded to the incorrect information appear to be clueless if they didn't quote the original text.
Thank you for the pointing that out and will do so in the future.
 

BobaMosfet

Joined Jul 1, 2009
2,110
My question has to do with through-hole Electrolytic Capacitor physical size and finding the correct specification in ordering a replacement.

Example: I’m working on an old video arcade monitor. The parts list calls for two (2) 6800uF, 50V Electrolytic Capacitors (ECap). Based on that specification, you can go to Mouser, DigiKey, etc and get a through-hole ECap at that spec…and get a far smaller one (physical size-wise) than what was on the board.

From my limited knowledge, I understand that size does matter in this application because of the stress that the circuit puts on the ECap in charging and discharging, so I’m assuming that its something to do with the operational frequency of the ECap.

My question:
Is there something on the old cap I can look at to get the right replacement part? Going just by the parts list, it doesn’t state size or frequency.

Is it better to measure the ECap that’s on the board first, and match-up the physical size and capacitor specs with the suppliers? Wondering how other experience repair shops solve this…especially when building a spare parts inventory.

Any help or direction would be most appreciated.

View attachment 227837View attachment 227838
Thank you for the clear, large pictures.

As you (and others have stated), it's a 6800uF 50V capacitor. It is also POLARIZED. All Electrolytic Capacitors are polarized. If you do not see bulging at the top or bottom, and don't see dialectric vented, the cap is probably fine. If you choose to replace it, size is an irrelevant concern.

The size of an electrolytic capacitor is directly related to nothing more than the quantity of material inside that forms both plates, and the dialectric (non-conductor) between them.

All that matters is rating- which is equivalent. 6800uF @ 50V, Polarized. Just get another Electrolytic.
 

MisterBill2

Joined Jan 23, 2018
18,175
Certainly the capacitors are polarized electrolytics, which may have already been stated. There are different brands and different qualities and so getting a similar rated one with a similar, but not identical size will be the best choice. Ripple current can be very important as well as voltage and capacitance. And temperature ratings do matter a lot.
 
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