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BeoMaster 700K: big capacitor replacement / looking for big size

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KolfMAKER
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KolfMAKER posted on Wed, Nov 10 2021 8:33 AM

In my BeoMaster 700K I have to replace the big capacitor sitting next to the power supply. It is:

  • 1000uF
  • 50 volts
  • 65mm long
  • 35mm diameter

I am looking for a replacement of the same size as the original.

anyone who can recommend me a good source / webshop for big size capacitors?

 


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Dillen
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Dillen replied on Thu, Nov 11 2021 4:25 PM

Not easy without going far to high in working voltage - which is absolutely not good.
I suggest fitting a new capacitor to the original bracket using a couple of crossed cable ties.

Don't fit a low-ESR type. That would be asking for trouble in this Beomaster.
Grab a good quality general purpose one.

Martin

KolfMAKER
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I always thought it was safe to use the specified voltage of a capacitor as a minimum. Therefor I was thinking about a capacitor of 1000uF but with a higher voltage than 50v (which is specified in case of the 700K). But anyhow, I see your comment that far too high in voltage is not good. So I take that into account.

Here are capacitors of 1000uF and 35mm diameter I found: click link

Questions

 

  1. The ones I found are at least 200 - 250 volts. Is that too high?
  2. I am not sure if these are(n't) low-ESR and I see differences in lifetime between 2,000 and 10,000 hours (the higher the better?). Can you recommend one in this list?  
  3. If you think I should take another one, can you recommend one (link to an example)?

 

Thnx Martin! Thumbs Up

Ernst

Dillen
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Dillen replied on Fri, Nov 12 2021 4:02 PM

If an aluminium electroytic capacitor isn't used up close to its voltage rating, even if only occasionally, it will not be excited, and it will die fast.
Popular speaking, you can say that it "dies from boredom".

I would suggest fitting a 50V or 63V. Nothing higher than that.
Something like this:
https://nl.rs-online.com/web/p/aluminium-capacitors/1636660

Martin

KolfMAKER
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Also thanks for explaining why too high voltage doesn't work well.
I'll follow your advice. Thumbs Up 

KolfMAKER
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One more question Martin, just to be sure.

I have just detached the original capacitor. One pin has one red wire connected. The other pin has 7 black wires connected. And on the side of the original capacitor, text says 'RED POS'. Normally I would say, sure where the red wire goes is the positive. But the pin with the black wires has a red dot. (see pictures)

So my question now is what to follow:

  • Red wire is positive
  • Pin with red mark is positive.

Hope to have your advise.


Dillen
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Dillen replied on Wed, Nov 24 2021 6:17 PM

Red tag is positive - for the capacitor!
The Beomaster as a whole, has positive ground. Hence the "confusion".
Just make sure you get the new cap polarized the same way the original was and everything will be fine.
If in doubt put a DC voltmeter across the cap and with the variac slowly bring up a little mains, just enough to see that the positive voltage is indeed found at the caps positive tag (which is connected to ground in the Beomaster).

Martin

KolfMAKER
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So this means that the black wires are connected to the positive pin of the capacitor?

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