Help find capacitor

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rubber_jonnie
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Re: Help find capacitor

Post by rubber_jonnie »

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 »

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 »

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 many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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Re: Help find capacitor

Post by Steve »

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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rubber_jonnie
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Re: Help find capacitor

Post by rubber_jonnie »

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 many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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Re: Help find capacitor

Post by Steve »

Yeah makes sense thx :)
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