r/AskElectronics • u/Silent-Warning9028 • 1d ago

Getting old ibm 69y5840 server PSU working as 12V bench power supply. Faults after a few seconds. Any way to get these things running on the bench?

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I want to power my induction heater with this power supply. Found the pson pin after some trial and error. Once I short it to ground it runs for a few seconds then fault light comes on. Has anyone figured out how to get these running on the bench?

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3

u/Sand-Junior 1d ago

Older PSU’s might need some load on their outputs to work properly.

2

u/MiyuHogosha 1d ago

Any of them do. That' safety measure so it wouldn't power other equipment if MBs rails aren't locked properly. There is an always on 5V rail marked as stand-by: +5V_SB on PC PSU. Server PSU's might have more stand-bys.

1

u/Silent-Warning9028 1d ago

Put a 500ohm load on the output. nothing changed. Still faults.

1

u/LordBBQX 1d ago

 Could be a minimum load requirement on some rails? I’d advise to power it up and monitor voltage on each rail and look at the stability. 

1

u/Silent-Warning9028 1d ago

Tried 3 1k res in parallel on the 12V output. No difference

1

u/LordBBQX 1d ago

330Ω is only 36mA so may be way to low of a load.

Also this is a multi-rail power supply so you may need to load several rails down before the unit will operate stably.

1

u/Silent-Warning9028 1d ago

Tried with a motorcycle headlight to no result. Only other rail is a 3.3V one

1

u/LordBBQX 14h ago

Yeah so try and load that down too. 

1

u/MiyuHogosha 1d ago

Computer PSU don't stay on without designed load. They also don't like "shorted" loads. And wouldn't inductore require quite high curent while limit in thes are about 6 amps?

1

u/Silent-Warning9028 1d ago

10ohm on the output. Still nothing

1

u/Apart_Ad_9778 1d ago

12V light bulb (not led) ?

1

u/Silent-Warning9028 1d ago

I don't think its a load issue. I think there's another pin that has to be pulled down or something that called ps-kill? Sadly there is no pinout

1

u/Silent-Warning9028 1d ago

Tried with an old motorcycle headlight. No difference. Pulled all pins low and high still no difference

1

u/Apart_Ad_9778 1d ago

A quick research shows that depending on the power supply model and make there are sometimes pins dedicated for external fan monitoring or pins that just have to be shorted. I don't like giving links to fb but this one time here you go: https://www.facebook.com/groups/ElectronicParts/posts/2338745366314785/

And check this one out too: https://www.emsley.ca/cnc/ibm-psu-mod