Member Avatar for TechTJ

Hello Everyone

I just got a old Computer from my gf family. i got it for linux and who can turn down a free computer. It has been sitting for a while in there garage but was covered up and taking care of. They took the HD so i put a new one in. But i notice that when i plug in the power cord the Power Supply begins to buzz even when the computer is not on. When you turn on the buzz goes down but fan dose not come on. CPU fan is working though. But the HD and everything Powers up. I just do not have an OS on there yet. So form my experience i would say its the Power supply but i wanted to get some advice to see maybe if i should check something else.\

Thanks in Advance
Tim

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  • Latest Post Latest Post by abel2b

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Short summary and quick context: reported a unit that buzzes when the mains is plugged in, powers fans and LEDs but never POSTs (drive LED stuck in standby). Contributors such as and already suggested the PSU or dried/bad capacitors; pointed out that low‑cost OEM desktops can make repairs awkward or uneconomic. Buzzing can be harmless coil whine but can also come from vibrating/aging components or arcing inside a PSU — it’s worth treating the noise as a diagnostic clue, not just an annoyance. (lifewire.com)

A short, safe diagnostic sequence (do these in order):

  1. Safety/visual check: unplug and inspect the PSU and motherboard for bulging or leaking capacitors, scorch marks or a burnt smell — visible capacitor damage is strong evidence of component failure. (en.wikipedia.org)
  2. Minimal bench test and POST signals: bench the board outside the case with only CPU, cooler, one RAM stick and PSU (and GPU only if required). Add a small POST speaker or watch any motherboard debug LEDs/beep codes; reset CMOS if needed. This isolates motherboard/DRAM/GPU issues from peripherals. (blog.silverpc.hu)
  3. Isolate the PSU — don’t open it: either swap in a known‑good, appropriately rated ATX PSU or use a commercial PSU tester/multimeter to verify the rails. Do not attempt internal PSU repairs unless qualified; the unit contains high‑voltage capacitors. (techcult.com)

Practical outcome: if a known‑good PSU lets the board POST, the original PSU was at fault; if the board still refuses to POST after minimal‑bench testing, the motherboard (or its power circuitry) is likely damaged and, on older OEM machines, replacement parts can be hard to source — salvaging RAM/CPU is often the best value.

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Member Avatar for TechTJ

Hello just wanted to update my Situation. So i turned it on today and the hard drive light just stays orange as in stand by. And everything powers up like i said in previous post but it dose not POST and dose not give me BIOS i think the mother board is fried. The light is on on the mother board and the CPU fan is running. But its an E machine so i think im just going to scrap it.

Thanks.
Tech TJ

Member Avatar for caperjack

sounds like it could be a bad power supply ,even though it powers the cpu fan ,it can still be bad

Member Avatar for TechTJ

so the PSU could still be bad even though the HD, CPU Fan HD and the mother board light comes on?

Thanks
Tim

Member Avatar for jbennet

btw if its an emachine the motherboard (and probaby the case, and posssibly the psu too) will be nonstandard so its probably best to just bin it instead of repair it.

Member Avatar for TechTJ

LoL thanks Jbennet I most likely will scrap it out but i just wish i could figure out what went bad on it. :)

Thanks Tim

Member Avatar for abel2b

Hey first off check all voltages are good on the psu, what you do is pull it out of the chasis test it alone, but you have to load it or it will blow. plug an old hard drive or just put a car 12v tail light bulb between any yellow and black cable coming out of the psu, and with a voltmeter check it has +12v,+5v,+3.3v,-5v,-12v coming out...

I repair these every day and my guess is that after been en storage for a long time, Capacitor on the circuit board dry out and don´t work like they should or short out, it also holds true for capacitors in the motherboard..

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