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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment. |
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29th Apr 2020, 3:10 pm | #1 |
Hexode
Join Date: Dec 2018
Location: Lugo, Spain
Posts: 477
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Power supply QRM shielding
I have a very nasty qrm coming from my psu inside the computer . Does anyone have any suggestions as to how to tackle this please . I have not had it apart yet so dont know if there are some critical filtering components missing !.
Thank you. |
29th Apr 2020, 5:41 pm | #2 |
Guest
Posts: n/a
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Re: Power supply QRM shielding
I think you are right about missing filter components, all too prevalent today. A portable radio waved around the mains cable will find out.
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29th Apr 2020, 6:22 pm | #3 |
Nonode
Join Date: Mar 2010
Location: Dukinfield, Cheshire, UK.
Posts: 2,034
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Re: Power supply QRM shielding
I found our previous PC was putting a lot of noise onto the mains lead and it was radiating all over the house.
So I made a short flylead which plugged into the PC's IEC socket and was fitted with a filtered IEC socket, see picture. This socket was mounted in a small plastic box for safety. Once fitted, peace & quiet reigned again! The filtered socket came from Surplectronics. https://www.surplectronics.com/ It's listed under capacitors.
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Andy G1HBE. |
29th Apr 2020, 7:14 pm | #4 |
Hexode
Join Date: Dec 2018
Location: Lugo, Spain
Posts: 477
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Re: Power supply QRM shielding
Thanks for replies. Looks like i,m going to have the lid off and take a look see first then maybe even roll my own filter , its very noisy its unreal on the s meter.
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29th Apr 2020, 7:39 pm | #5 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,806
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Re: Power supply QRM shielding
You'll probably find a nice virgin area on the PCB ready for X and Y capacitors, and a pair of links where a common mode choke ought to have been. Probably was on the one sent for testing. Fitting these ought to be a start. Adding a big ferrite on the output wires might help as well. 1 per connector.
David
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Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |
29th Apr 2020, 9:39 pm | #6 |
Hexode
Join Date: Dec 2018
Location: Lugo, Spain
Posts: 477
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Re: Power supply QRM shielding
Yep, that's got me curious now as to missing stuff!!!. We shall see.
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