Very strange noise from atx power supply

Thread Starter

Martiio

Joined Apr 2, 2020
43
Hello everybody.I have a problem with an old power supply.When I turn the supply on i hear very strange noise coming from the psu.I thought it's fan problem,but it isn't.I changed the fan and the problem did not disappear.What might be the problem?
 

zophas

Joined Jul 16, 2021
156
A "strange noise" could be anything. Is it a tick-tick, a tok-tok, a brrrrrrring, a pop-pop, a fizzzzzzz, a shhhhhhhhzing? And since you have had the thing open it should be easy to locate the source of the strange noise. More info required.
 

Thread Starter

Martiio

Joined Apr 2, 2020
43
A "strange noise" could be anything. Is it a tick-tick, a tok-tok, a brrrrrrring, a pop-pop, a fizzzzzzz, a shhhhhhhhzing? And since you have had the thing open it should be easy to locate the source of the strange noise. More info required.
something like fizzzzzz
 

zophas

Joined Jul 16, 2021
156
I suggest you check for leaking and/or bulging capacitors. ATX supplies are notorious for having those fail. If you really want to fix this yourself I think you will need a schematic for it. Then maybe we could talk about checking some components and voltages. Normally ATX supplies are not worth repairing considering the difficulty of finding info on them.
 

Tonyr1084

Joined Sep 24, 2015
6,459
IF - and this is a HUGE "IF" - IF the fizzing sound is not going to do immediate damage then using a small soda straw to your ear and the board, you should be able to locate the source of the sound. HOWEVER - AND THIS IS WHERE THE BIG "IF" COMES IN - IF the fizzing sound is a failure mode in progress, running the supply to find the noise will damage it.

Now, Fizz, Fuzz, Buzz, however you define a noise - the fact remains - something is wrong. This supply, if continuing to operate, will fail in short order. Possibly before you can locate the source and rectify it. zophas has a pretty good idea - look for bulging capacitors for starters. And before you go touching things, remove the plug from the unit or the wall. Let it sit for an hour or more before you start gerfingerpokin. Otherwise you may discover a healthy charged capacitor with teeth. And the sudden uncontrollable withdraw of a hand or finger can result in gashing the back of your hand against a sharp metal edge.

ATX supplies are known as Switch Mode Power Supplies, or SMPS. They operate on the principal of converting line voltage to a high frequency somewhere typically above 20KHz. Certainly not a hissing or fizzing noise if running properly. That high frequency is then turned on and off at that frequency. Depending on the time the PS pulse is high versus its low (on and off) results in an average voltage which is then filtered and sent out to the electronics it's running. Therefore there is a potential danger of a failure mode where excessive voltage may be applied to the load. Or the human who may be so unlucky as to be touching something at that moment. Ouch. Or "Good Night Louise". So be careful about how you go about finding and fixing the problem. IF it can be found and fixed.
 

Thread Starter

Martiio

Joined Apr 2, 2020
43
IF - and this is a HUGE "IF" - IF the fizzing sound is not going to do immediate damage then using a small soda straw to your ear and the board, you should be able to locate the source of the sound. HOWEVER - AND THIS IS WHERE THE BIG "IF" COMES IN - IF the fizzing sound is a failure mode in progress, running the supply to find the noise will damage it.

Now, Fizz, Fuzz, Buzz, however you define a noise - the fact remains - something is wrong. This supply, if continuing to operate, will fail in short order. Possibly before you can locate the source and rectify it. zophas has a pretty good idea - look for bulging capacitors for starters. And before you go touching things, remove the plug from the unit or the wall. Let it sit for an hour or more before you start gerfingerpokin. Otherwise you may discover a healthy charged capacitor with teeth. And the sudden uncontrollable withdraw of a hand or finger can result in gashing the back of your hand against a sharp metal edge.

ATX supplies are known as Switch Mode Power Supplies, or SMPS. They operate on the principal of converting line voltage to a high frequency somewhere typically above 20KHz. Certainly not a hissing or fizzing noise if running properly. That high frequency is then turned on and off at that frequency. Depending on the time the PS pulse is high versus its low (on and off) results in an average voltage which is then filtered and sent out to the electronics it's running. Therefore there is a potential danger of a failure mode where excessive voltage may be applied to the load. Or the human who may be so unlucky as to be touching something at that moment. Ouch. Or "Good Night Louise". So be careful about how you go about finding and fixing the problem. IF it can be found and fixed.
I found one of the capacitor
I suggest you check for leaking and/or bulging capacitors. ATX supplies are notorious for having those fail. If you really want to fix this yourself I think you will need a schematic for it. Then maybe we could talk about checking some components and voltages. Normally ATX supplies are not worth repairing considering the difficulty of finding info on them.
I found that one of the capacitor is bulging which is 6.3v 3300uf.Can that be the problem with the noise? Unfortunately I don't have such a capacitor!Can I replace it with 10v 2200uf.
I suggest you check for leaking and/or bulging capacitors. ATX supplies are notorious for having those fail. If you really want to fix this yourself I think you will need a schematic for it. Then maybe we could talk about checking some components and voltages. Normally ATX supplies are not worth repairing considering the difficulty of finding info on them.
I found one of the capacitor is bulging.This capacitor is 6.3v 3300uf.Unfortunately I don't have such a capacitor at the moment.Can I replace it with 10v 2200uf
 

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ericgibbs

Joined Jan 29, 2010
14,183
hi M,
I would suggest you fit the 2200uF, it will give you an idea if there are any other problems with the board.
Let us know how it goes.
E
 
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