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Smoothing capacitor replacement

W

Wayneos

Jan 1, 1970
0
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!!
 
D

Dave Plowman (News)

Jan 1, 1970
0
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??)

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.
 
W

Wayneos

Jan 1, 1970
0
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.
 
D

Dave Plowman (News)

Jan 1, 1970
0
I wasn't thinking along those lines, I was taking the view that on most
capacitors it's the negative that's marked.

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?
Anyway thanks for the advice.

No problem.
 
W

Wayneos

Jan 1, 1970
0
Yeah, all the clues were there, looking at it now I can't believe I
wired 'em up wrong! Should have just taken the £10 and set fire to it.
Oh well, learn by your mistakes and all that...
 
N

NSM

Jan 1, 1970
0
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

Yes. You should check with a meter first.

N
 
E

Engineer

Jan 1, 1970
0
Wayneos said:
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!!

(snip)

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

Christian Treldal

Jan 1, 1970
0
Den Tue, 14 Jun 2005 08:22:33 -0700. skrev Wayneos:
Yeah, all the clues were there, looking at it now I can't believe I
wired 'em up wrong! Should have just taken the £10 and set fire to it.
Oh well, learn by your mistakes and all that...

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

Dave Plowman (News)

Jan 1, 1970
0
And if you gave 10£ your component pusher will be laughing all the way to
the bank;-)

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

Wayneos

Jan 1, 1970
0
Yeah - I needed TWO of them + postage = about a tenner.
I wonder if they'll accept them as faulty? (joke)
 
N

NRen2k5

Jan 1, 1970
0
Why did you think red was negative?

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

- NRen2k5
 
N

NSM

Jan 1, 1970
0
Because the convention is if you're only marking one, you're making
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
 
W

Wayneos

Jan 1, 1970
0
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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