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 Post subject: Capacitor identification.
PostPosted: Aug Wed 07, 2019 3:41 am 
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Joined: Apr Mon 16, 2018 2:51 am
Posts: 8
I am somewhat new to this . I have a Silver Marshall Model 30. It has 4 small metal capacitor boxes (3 caps each) and One larger 1 (4 caps) all full of tar. There is also one 2 mfd slim can installed on top of the chassis. The schematic tells me the value but no the voltage rating. Should I replace the caps and with what voltage rating? Also how do I know if they are electrolytic or just a filter bypass. There is one 8 mfd electrolytic identified in the chassis.


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 Post subject: Re: Capacitor identification.
PostPosted: Aug Wed 07, 2019 2:51 pm 
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Joined: Jun Wed 08, 2011 2:33 am
Posts: 9123
Location: Ohio 45177
I looked at the schematic online and one has a voltage chart for the different tubes. It says 280V on the rectifier. Lower downstream from there, but then that is with 110V line voltage probably, so it may be a few percent higher on something like 120V lines. Thus I would make the caps at least 350V rated. That is common voltage for electrolytics you can buy now. 350- 450V are common replacement voltage ratings. IF you cannot find the exact capacitance values, go next value higher that you can find, like 4uF could be 5, 1,2, 8-10 etc. but I would not go a great deal higher in value. The common values of caps are not the same as they were, now.

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 Post subject: Re: Capacitor identification.
PostPosted: Aug Wed 07, 2019 3:57 pm 
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Joined: Jan Mon 18, 2010 2:13 am
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Location: Dayton Ohio
Most capacitors in the 2 mfd range and under are likely paper. 8 mfd was the first common electrolytic value. Even 8 mfd can be found easily as a mylar/poly type which will work fine (if not better).

https://www.tubesandmore.com/products/c ... ylene-fast

Just use 630V mylar/poly caps and it will cover all bases. They are significantly smaller than the old ones anyway.

-Steve

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 Post subject: Re: Capacitor identification.
PostPosted: Aug Wed 07, 2019 10:06 pm 
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Joined: Apr Mon 16, 2018 2:51 am
Posts: 8
Thanks for thee information but should I be replacing all of the caps in the tar boxes with electrolytics'?


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 Post subject: Re: Capacitor identification.
PostPosted: Aug Wed 07, 2019 10:31 pm 
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Joined: Jan Mon 18, 2010 2:13 am
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Location: Dayton Ohio
You could if you really want to, but I would recommend replacing them with mylars.

You can get most values from Sal or Just Radios with the ads on the right.

-Steve

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-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!


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 Post subject: Re: Capacitor identification.
PostPosted: Aug Thu 08, 2019 1:26 am 
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Joined: Apr Mon 16, 2018 2:51 am
Posts: 8
Thank you.


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