What’s this component ?

[andyrlb]

Hi guys ,
Thought I’d give the potentiometers a clean on the Revox b750 and whilst that was a success I noticed a distorted/burnt component on the power selector switch on the rear of the amp , I obviously need to replace it but I’m not sure what to look for or order , any help please? https://uploads.tapatalk-cdn.com/20181129/00dbd372bce74050998782b73c34936b.jpg


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[struth]

Looks like an x2 suppressor capacitor.

[NRG]

Yes an x2 paper suppression cap, 250v rated. Modern polypropylene replacements can be found at RS, Farnell, CPC, Digikey etc.

https://cpc.farnell.com/c/electronic-electrical-components/capacitors/x2-capacitors

[andyrlb]

Looks like an x2 suppressor capacitor.

Cheers Grant , that’s coming up trumps [emoji1303]
Just got to find the correct values


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[andyrlb]

Yes an x2 paper suppression cap, 250v rated. Modern polypropylene replacements can be found at RS, Farnell, CPC, Digikey etc.

https://cpc.farnell.com/c/electronic-electrical-components/capacitors/x2-capacitors

Cheers Neal [emoji1303][emoji1303]


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[Firebottle]

Can't see what value it is on top but it MUST be rated X2 as it is connected across the mains.

If the replacement doesn't have X2 on it do not fit. X2 indicates a self healing capacitor.
Most modern X2 rated caps are now rated at 275V or even 300V AC.

[andyrlb]

Can't see what value it is on top but it MUST be rated X2 as it is connected across the mains.

If the replacement doesn't have X2 on it do not fit. X2 indicates a self healing capacitor.
Most modern X2 rated caps are now rated at 275V or even 300V AC.

Thanks Alan [emoji1303][emoji1303]


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[Light Dependant Resistor]

Its a Siemens brand, Kemet Paper capacitor, with what looks to be of 100nf or 0.1uf value


Sorry I had the wrong part of the schematic ... as you said it is across the power selection switch
I was misled thinking it was a front panel switch part of the loudness circuit... Yes agree
with other posts. Checking the schematic it is on page 3 of the B750 schematic straight after the fuse
across active and neutral, and indeed is 100nf @ 250vAC

[andyrlb]

Its a Siemens brand, Kemet Paper capacitor, with what looks to be of 100nf or 0.1uf value


Sorry I had the wrong part of the schematic ... as you said it is across the power selection switch
I was misled thinking it was a front panel switch part of the loudness circuit... Yes agree
with other posts. Checking the schematic it is on page 3 of the B750 schematic straight after the fuse
across active and neutral, and indeed is 100nf @ 250vAC

Thanks for the input and confirmation Chris .


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[sq225917]

I'd be tempted to look for a metalised film replacement rather than a like-for-like metalised paper.

Class X caps are there to block differential mode noise, might be worth investigation what caused the failure.

[andyrlb]

I'd be tempted to look for a metalised film replacement rather than a like-for-like metalised paper.

Class X caps are there to block differential mode noise, might be worth investigation what caused the failure.

Cheers Simon


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[sq225917]

To be fair, it's probably age that caused the failure. A film replacement will be self healing and as such, longer lasting.

[reddish75]

Those caps are failing in equipment left right and centre, replace with the same type and rating just not the same brand

[andyrlb]

Those caps are failing in equipment left right and centre, replace with the same type and rating just not the same brand

Doing exactly that [emoji1303]


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[Minstrel SE]

Yeah it looks like the evox rifa capacitors that I have been buying on ebay...just convert the uf to nf.....how its stated on the new equivalents...they will now be rated at 250v.

I got the same looking direct replacements 30 years later