[vcf-midatlantic] Old AT power supplies - how to test?

William Dudley wfdudley at gmail.com
Sat Dec 28 12:51:16 EST 2019

You can buy AT powersupply testers.

Beware, the cheaper ones just light an LED if there's any voltage at all
This is not good if the voltage is high enough to destroy a motherboard.

Better ones actually give you pass/fail on each different voltage.
The typically have multiple connectors on them to work with different era
power supplies, as the number of connectors and number of pins on the big
connector have changed over the years.

I think I have this one:


The present the minimum load possible to get the supply to run.  For a load
test, follow
the recommendations of others on this list.

Bill Dudley
retired EE
This email is free of malware because I run Linux.

On Sat, Dec 28, 2019 at 10:06 AM John Heritage via vcf-midatlantic <
vcf-midatlantic at lists.vcfed.org> wrote:

> Hey folks,
> I have a couple of old DOS/Win98 (OS/2) era systems that I came across, and
> they both have AT PSUs I want to check out before powering on for the first
> time.
> I was thinking before powering on:
> - Open the PSU
> - Air spray the PSU
> - Look for obvious signs of failure - capacitor leakage, burnt PCB, burnt
> components
> If all looks OK - do these require a load, or can I at least test basic
> voltage with no load?
> I do have heat resistors (used to balance out ATX PSUs for a 3D Printer)
> that I believe I can plug in on the 5V or 12V rails and test voltage
> there..
> How much testing should I do / what do you recommend?
> Thanks!
> John

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