Question about capacitors

MaximRecoil

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I want to replace the 330μF 200V (location = C5) radial capacitor in my Nintendo Punch-Out power supply (PP-1000A). The original capacitor is short and fat, while the only replacement of that value I can find is tall and thin; enough so that when the power supply is assembled, the top of the capacitor would just contact the metal housing of the power supply.

The question is: is that a problem? If so, can I put a piece of rubber or electrical tape on the top of the capacitor, to go between it and the metal housing of the power supply, for insulation?
 
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It doesn't matter at all... I'd actually be more worried about the stress of the metal cage pushing down on it than any electrical contact.

DogP
 
It doesn't matter at all... I'd actually be more worried about the stress of the metal cage pushing down on it than any electrical contact.

DogP

It just barely makes contact, so that's not an issue. If the capacitor was even a hair shorter, it wouldn't make contact at all. When you set the cage onto the top to be screwed down, all the screw holes line up as-is. You don't have to force it at all.

I stuck a single piece of electrical tape on top of the capacitor and reassembled it. It works fine.

Note to anyone who has a Punch-Out power supply: you should check the C8 capacitor. The schematics for the PP-1000A power supply show a 47μF 35V capacitor at that location. When I originally took mine apart to check the values of all the radial capacitors in order to buy replacements, I noticed it had a 100μF capacitor at C8. I thought that was odd, but I ordered the same value for a replacement (a 50V version though).

Then I remembered reading this from the Star Tech Journal:

pp-1000, pp-1200, pp-1300 power supplies must have c8 replaced!
use 100mfd at 35v, 105 degrees centigrade.
failure of cap causes overvoltage and board destruction.

So if you have a 47μF capacitor at C8 (or even if you have a 100μF but it is old), you might want to replace it with a new 100μF capacitor. I used a Panasonic FM 100μF 50V (link). I actually replaced all of the radial capacitors on the board with new Panasonic capacitors. It came to about $15 shipped (the big 330μF 200V one was $4.50 by itself).
 
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Some power supplies are like this from the factory. They usually have a small circle of a cardboard type material glued to the top of the cap.
 
I just ran into a similar problem when recapping a switcher. I figured it was better to cut a hole in it, then touch the top. I had no basis in fact to go on, but I did it just to be safe. These comments suggest it was the right thing to do. Of course if it was an OEM power supply, I might have thought twice.
 
I'd go to Mouser and dig through the data sheets for caps to find one that would fit better.

The issue you'll have with the cap being sandwiched is that it won't be able to properly vent if it fails.

RJ
 
I'd go to Mouser and dig through the data sheets for caps to find one that would fit better.

The issue you'll have with the cap being sandwiched is that it won't be able to properly vent if it fails.

RJ

That's what I ended up doing. I found one made by Nichicon that was pretty close to the dimensions of the original capacitor, and fit in there fine with nearly a half inch of clearance between the top of it and the power supply housing.
 
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