Author Topic: Filtering SMPS for noisy computer  (Read 302 times)

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Offline cleanworkbench

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Filtering SMPS for noisy computer
« on: May 02, 2020, 07:37:21 am »
I have a problem with radio interference from the computer PSU.  Make is ATX 500TD
As per usual the mains input filtering components are missing . So what are the values for the caps and toroid windings or the toroid colour , wire diameter and turns  count . I either solder in to the PCB or build a small board and fit inside the box. And what about the DC o/p filtering ???.
Anyone done this here please ?

Thanks
 

Offline David Hess

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Re: Filtering SMPS for noisy computer
« Reply #1 on: May 02, 2020, 08:04:07 am »
I would tend to add an existing line input filter module rather than designing one from scratch; they are not expensive.  They are also available with an IEC connector for using standard power cords if a panel mount is acceptable.
 

Offline cleanworkbench

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Re: Filtering SMPS for noisy computer
« Reply #2 on: May 02, 2020, 08:14:55 am »
I take your point but i have loads of components here .
 

Offline ogden

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Re: Filtering SMPS for noisy computer
« Reply #3 on: May 02, 2020, 08:40:56 am »
This is safety-related job which requires qualification. Either you are skilled enough to do the job w/o askign questions in the public forum or you are not qualified. Install premade AC mains line filter (if any) or better buy new PSU ensuring that it has EMI filtering and sell existing one.

 

Online TheMG

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Re: Filtering SMPS for noisy computer
« Reply #4 on: May 02, 2020, 05:04:35 pm »
As per usual the mains input filtering components are missing .

Are you saying the filtering components inside the PSU itself have been omitted?

That's a sign of a cheap piece of junk PSU. Likely other corners have been cut too, so it's probably not going to be an efficient or reliable PSU either.

I would just get a better quality PSU.
 

Offline wraper

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Re: Filtering SMPS for noisy computer
« Reply #5 on: May 02, 2020, 05:25:05 pm »
The best would be to replace it with decent quality PSU instead of investing your time and money into piece of junk. Crap PSU have significant chance damaging computer hardware and they are inefficient. Usually price difference between crap and good PSU will turn the other way around when counting electricity cost difference over computer lifetime, so you will pay more instead of saving. You may think that power consumption difference of something like 20W is nothing, but say when used for 8 hours a day, it's 58 kWh per year, multiply by 23.8 euro cents per kWh and it's 14 Euro annually. Not to say they also usually have poor standby PSU efficiency as well which adds up as well.
 

Offline cleanworkbench

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Re: Filtering SMPS for noisy computer
« Reply #6 on: May 02, 2020, 09:02:54 pm »
Its the usual trick for cost cutting , leave out EMI components , its served me well but i thought i would pop the lid for a look see and sure enough , two toroids and three caps missing.  I have another psu ready to go in but want to see if i can get the RFI down or completely gone.
 


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