Smoothing capacitor replacement

Jun 14, 2005 12 Replies
W

Hi, I need to replace my smoothing capacitors in my guitar amp - they're



5000uf 50v. I tried some 4700uf 63v ones but they blew up!! I couldn't tell the polarity of the original ones - they just had a pink dot on one of the terminals, which I assumed was negative, so wired the new ones accordingly. Did they blow because of the incorrect polarity or are they the wrong rating? If they are the wrong rating, can anyone point in the direction of the correct replacements (maplin order code or something??)

Cheers in advance for the help!!



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D

Pink would have originally been red, so positive. Black would be negative. On all the electronics I've come across.

Why did you think red was negative?

5000uF 50v is an old standard value. 4700 63V should work just fine.
*(on a baby-size shirt) "Party -- my crib -- two a.m Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound.
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W

I wasn't thinking along those lines, I was taking the view that on most capacitors it's the negative that's marked. Anyway thanks for the advice.

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D

Ahh - true. But with a - sign, not a colour?

But if it had a marked tag, surely it was wired rather than PCB mounting? If so, what colour were the wires?

No problem.

*I don't suffer from insanity; I enjoy every minute of it. Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound.
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W

Yeah, all the clues were there, looking at it now I can't believe I wired 'em up wrong! Should have just taken the =A310 and set fire to it. Oh well, learn by your mistakes and all that...

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N

Yes. You should check with a meter first.

N
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E

(snip)

What sad story... gotta go and get a beer so I feel better Pink is Positive... Red is positive... Plus is positive... What other clues have I missed? Measure twice, solder once! Cheers, Roger

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C

Den Tue, 14 Jun 2005 08:22:33 -0700. skrev Wayneos:

And if you gave 10£ your component pusher will be laughing all the way to the bank;-)

Best whishes Christian Treldal
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D

'Audio' grade 4700uF 63v are 4 gbp at Maplin.

*Snowmen fall from Heaven unassembled* Dave Plowman dave@davenoise.co.uk London SW To e-mail, change noise into sound.
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W

Yeah - I needed TWO of them + postage = about a tenner. I wonder if they'll accept them as faulty? (joke)

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N

Because the convention is if you're only marking one, you're making negative.

- NRen2k5

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N

negative.

Actually that isn't the convention, it's just that some Asian makers did it that way for their own reasons. If you are old enough to remember the multisection caps used for tube radios and TVs you'd remember them being marked on the positive terminals with various symbols.

N
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W

Anyway, thanks for the advice Dave - I'll get some more caps from Maplin and hopefully have a less smokey time fitting them!!

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