On 12/28/2019 10:05 AM, John Heritage via vcf-midatlantic 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
IBM used to sell a load kit for the AT (typically called a sandbar due to the appearance of the load resistors inside) as some of the older PSU would loose regulation and essentially self-destruct without a load Made a home-brew version with a pair of Dale 250W, 20 ohm resistors. The first is +5 to ground, the second is +12 to ground. A later addition was a 12 volt fan. As to the test, I usually I set it up and let it run for an hour with the above load, with a scope to measure voltage and ripple. Martin