Replacing broken XT PSU with modern one. \ VOGONS

Replacing broken XT PSU with modern one.

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First post, by Matrolisk

Matrolisk Offline

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I have an old 5160 pc with a broken PSU, I'm planning to replace it with a modern one and could use some advice.

The unit I've picked is the Apevia 300W Flex ATX Power Supply TFX-AP300W since it will easily fit inside the old PSU case allowing me to keep the original pc aesthetic.

My first issue is that the+5V rail only supplies 12A while the original PSU had 15A.

The second one is that it has an original sound blaster 2.0 which needs the -5V. I know about the voltage blaster but since it draws from the -12V rail I'm worried there won't be enough power.
The new unit supplies .3A on the -12V rail which is slightly more than the original, but the -5V rail needs .3A on it's own.

Reply 1 of 3, by DaveDDS

Posted on Today, 15:13

DaveDDS Offline

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I doubt 12 vs 15a would be a problem on an XT unless you have it very heavily loaded - you could measure to be sure.

-5 is always almost no current - I sometimes just put a 7905 -5v regulator on -12

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Reply 2 of 3, by Matrolisk

Posted on Today, 16:30

Matrolisk Offline

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So just take the incoming -12V wire and split it into two wires? One going to the -12V input on the motherboard the other passing through a 7905 then going to the -5V input on the motherboard?

Should I use capacitors like the Voltage Blaster does?

Reply 3 of 3, by DaveDDS

Posted on Today, 19:59

DaveDDS Offline

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That's pretty much it - probably worth measuring the current on the -5, just to see if you need any sort of heat-sink (probably not)

From -12, -5 will "drop" 7v - current will be very low, but even at 10ma if would mean 70mw of disappation - depending the case of the regulator, with no heatsink at all it might get a little warm.

I'm also a big believer in current limiting - over the years I've gotten pretty good a fashioning vert low current "fuses" using bit of super-fine wire... you'll have to decide if it's worth the effort in this case.

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