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 Capacitor question(s)

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Mike W.

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PostSubject: Capacitor question(s)   Wed Oct 13, 2010 3:08 pm

Hey guys, bummer about the forum. I was quadlibet2001 on that one.
Anyways, I have a question that I partly know the answer to. I have a silvertone 2268 (c.1961) stereo record player arriving soon, that was listed for repair. One of the obvious capacitors sticking out like a sore thumb on the photofact is a multisection cardboard can of 150@150/150@150/150@150/25@25. Mouser lists their 150@150s as REALLY expensive, while the 150@160 is chump change in comparison. Now I know that raising the voltage up 10 volts from 150 to 160 isn't that big a deal. But what my question is, when does it become a big deal? I think I read that upping the voltage too much on an electrolytic and it won't do its job anymore. Like it has to be at a certain voltage to WORK, hence the term working voltage. So whats the percentage rule of thumb for this? replacing a 150v with a 160 is fine but a 150v with a 600v not so good.
Same question for the capacitance. going up a little from 150uF to 160 again isn't much different, but too far up is bad news. Now....this is a silvertone so I'm guessing cost cutting was fit in wherever possible, capacitors included. Also todays line voltage is higher than the listed 117v it wants, so should the value of this multi-can be changed in line with todays power, or should I run it with a step down transformer (have plenty) @ 117?
Also size is a factor too since I'd like to re-stuff this one.
What you guys recommend?
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smeezekitty

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PostSubject: Re: Capacitor question(s)   Wed Oct 13, 2010 3:13 pm

Mike wrote:
Hey guys, bummer about the forum. I was quadlibet2001 on that one.
Anyways, I have a question that I partly know the answer to. I have a silvertone 2268 (c.1961) stereo record player arriving soon, that was listed for repair. One of the obvious capacitors sticking out like a sore thumb on the photofact is a multisection cardboard can of 150@150/150@150/150@150/25@25. Mouser lists their 150@150s as REALLY expensive, while the 150@160 is chump change in comparison. Now I know that raising the voltage up 10 volts from 150 to 160 isn't that big a deal. But what my question is, when does it become a big deal? I think I read that upping the voltage too much on an electrolytic and it won't do its job anymore. Like it has to be at a certain voltage to WORK, hence the term working voltage. So whats the percentage rule of thumb for this? replacing a 150v with a 160 is fine but a 150v with a 600v not so good.

This is no longer true.
You could use a 630v capacitor just as well.
It may have higher esr but you wouldn't notice this very much.
160 is even better because it allows you some voltage tolerance.
Quote :

Same question for the capacitance. going up a little from 150uF to 160 again isn't much different, but too far up is bad news. Now....this is a silvertone so I'm guessing cost cutting was fit in wherever possible, capacitors included. Also todays line voltage is higher than the listed 117v it wants, so should the value of this multi-can be changed in line with todays power, or should I run it with a step down transformer (have plenty) @ 117?
Also size is a factor too since I'd like to re-stuff this one.
What you guys recommend?
No.
150uf is more then enough.
Must radios have 60 uf or so.
Also do not worry about line voltage unless it is a transformer radio and the transformer is running hot.
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Mike W.

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PostSubject: Re: Capacitor question(s)   Wed Oct 13, 2010 8:17 pm

Ok, Thanks for the reply. Now a question about capacitor characteristics. Ive read that new capacitors outshine the old ones in performance and reliability by a landslide. But how about those different KINDS of electrolytics? While browsing mouser earlier today I saw a bunch of 25uF/25v electrolytics to help re-do a multi section can. I figured any old 25v/25uF lytic would do, but the descriptions at the far right got me wondering..... I sorted them out to list size-wise smallest to biggest, since they're hopefully going to fit in this can. The smallest one was listed as "low leakage" the one under it was listed as "high temp", and then another was "general use". Now normally I'd think that a 20% electrolytic general use capacitor is going to be just fine in an older set, but the cheapest, and SMALLEST (most important factor in this case) was a low leakage.
Does it matter what KIND of 25v/25uF electrolytic I use?
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Don Cavey



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PostSubject: Re: Capacitor question(s)   Wed Oct 13, 2010 8:25 pm

Size can be an issue if you want to stuff it into another older capacitor container. And a new electrolytic that is rated 105 degrees C is better than one that is rated 85 degrees C. But if we are talking an AC/DC radio does it really have to be that good?
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Mike W.

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PostSubject: Re: Capacitor question(s)   Wed Oct 13, 2010 8:31 pm

Well no, I doubt it has to be good, or audiophool quality. I was just wondering if a "low leakage" capacitor would be worse than a "general purpose" type. So far I like the "low leakage" because of it's size, but if a general purpose or high temp cap is better, then I'd rather be closer to what the schematic wants.
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tubes4life



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PostSubject: Re: Capacitor question(s)   Wed Oct 13, 2010 9:02 pm

If it's got enough capacity (uf) and it has enough working voltage, it's good enough, regardless of size.
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Bob D.



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PostSubject: Re: Capacitor question(s)   Wed Oct 13, 2010 9:51 pm

[quote=" Now I know that raising the voltage up 10 volts from 150 to 160 isn't that big a deal. But what my question is, when does it become a big deal? I think I read that upping the voltage too much on an electrolytic and it won't do its job anymore. Like it has to be at a certain voltage to WORK, hence the term working voltage. So whats the percentage rule of thumb for this? replacing a 150v with a 160 is fine but a 150v with a 600v not so good.
Same question for the capacitance. going up a little from 150uF to 160 again isn't much different, but too far up is bad news.
[/quote]

I don't think it ever becomes a big deal. One might even argue that increasing the capacitance and/or voltage rating of an electrolytic is a good thing, especially in a power supply.

Bobby D.
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glasdave

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PostSubject: Re: Capacitor question(s)   Wed Oct 13, 2010 11:51 pm

The nichicon 22mfd, 63 volt, 105 degree rated radial cap, that is about the size of 2 match heads, and will work just fine for your needs.

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radiorich



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PostSubject: Re: Capacitor question(s)   Thu Oct 14, 2010 1:01 am

Hello mike,
First all I've been ordering from mouser since the mid 80s.
They have treated me well .
Far as Caps I've had very good luck with nichicon sprague .

rich
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Alan Douglas



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PostSubject: Re: Capacitor question(s)   Thu Oct 14, 2010 10:26 am

Modern (anything since 1950) capacitors can run at any voltage up to their rated working voltage, with no problems of any kind.

Some of the "information" on the internet is from Deeley's book on electrolytics published in 1938. That's garbage.
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