I'm restoring an Atari 800XL. The caps were probably OK but I decided to recap anyway.

Some of the caps are axial and 22uF / 16V.

I have some 22uF / 25V but are radial. I don't normally like doing the "bend the legs and make it fit" routine. But I also don't want to buy more axial caps unless I have to (they are pricey!).

Now, I do have some 47uF / 25V axial caps already.

On the Atari, three of those caps are located right next to the power input. I can't seem to find the actual schematics. But my thoughts are that they are not used for timing and are probably used for power filtering.

My gut instinct says that for those three particular caps, I can use a larger uF rating (47uF instead of 22uF) and it will be fine.

What do you guys think?

If anyone has the actual schematics, maybe I can make a more educated guess. Not sure why my search skills don't find them.

Thanks!

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Cat; the other white meat.

The service manual for the 800XL can be found here: http://www.atarimania.com/documents/Atari%20800XL%20Service%20manual.pdf

The schematic is the last 4 pages. Looks like you could make the change. They are just PS filters.

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Bill

Oh my. I see that now. I found that document earlier but was browsing on my phone. I guess the PDF reader on it wasn't working or something.

Thanks!

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Cat; the other white meat.

It looks like there are four 22µF caps in total - C2, C3, C10, C79. I think all of them can be changed for 47µF ones without trouble.

Yep. I wasn't too sure about C79 but I think I will chance it. What's the worst that could happen?

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Cat; the other white meat.

I think C79 is a +5V supply line to an external device - a cassette deck. It has an LC filter to isolate load transients in the latter from the power supply of the computer itself. So a modest increase in the value of C is fine for the same reason as on any other supply voltage plane.