Help find capacitor

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rubber_jonnie
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Re: Help find capacitor

Post by rubber_jonnie » Fri Apr 09, 2021 11:41 am

exxos wrote:
Fri Apr 09, 2021 11:33 am
Just as a side note, High voltage capacitors near rectifier are usually suppression capacitors XY rated type stuff. They are designed to take a lot more hammering than regular caps are.

This one seems to be a good page about them..

https://www.allaboutcircuits.com/techni ... apacitors/
I've watched quite a bit on Big Clive about X/Y class caps and did wonder if it was for that purpose.
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Re: Help find capacitor

Post by exxos » Fri Apr 09, 2021 11:46 am

rubber_jonnie wrote:
Fri Apr 09, 2021 11:41 am
I've watched quite a bit on Big Clive about X/Y class caps and did wonder if it was for that purpose.
yep.. Normal capacitors would say have a 400V rating may take voltages up to double that for very short amounts of time. The XY caps can withstand peak voltages up to even several thousand volts. They are just designed to take the abuse which can come down the mains line and suppress it to stop it from killing the rectifier and other components as easily etc ordinarily a normal capacity would just simply explode.. It could have just simply being the reason for the failure in the original post.
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Re: Help find capacitor

Post by rubber_jonnie » Fri Apr 09, 2021 1:21 pm

exxos wrote:
Fri Apr 09, 2021 11:46 am
rubber_jonnie wrote:
Fri Apr 09, 2021 11:41 am
I've watched quite a bit on Big Clive about X/Y class caps and did wonder if it was for that purpose.
yep.. Normal capacitors would say have a 400V rating may take voltages up to double that for very short amounts of time. The XY caps can withstand peak voltages up to even several thousand volts. They are just designed to take the abuse which can come down the mains line and suppress it to stop it from killing the rectifier and other components as easily etc ordinarily a normal capacity would just simply explode.. It could have just simply being the reason for the failure in the original post.
Yes, quite possible that it had had enough abuse from the mains and died.
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
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Re: Help find capacitor

Post by Steve » Mon Apr 19, 2021 7:16 pm

Hey guys, I replaced the capacitor and bridge rectifier but it still isn't working. I made sure the input is getting 240v AC but I'm getting nothing on the DC output. I checked the round slow blow fuses and they seem fine. Can anyone else recommend what might be worth checking / replacing? Or the next logical step.

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Re: Help find capacitor

Post by rubber_jonnie » Mon Apr 19, 2021 7:21 pm

Is the bridge rectifier getting AC and providing DC? If not then that's where I'd start and then work my way through part by part.
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
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Re: Help find capacitor

Post by Steve » Mon Apr 19, 2021 7:45 pm

Yeah makes sense thx :)
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