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Hoffman Amps Forum image Author Topic: Best replacement for a 70uf filter cap Twin Reverb AC568  (Read 1698 times)

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Offline Planobilly

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Best replacement for a 70uf filter cap Twin Reverb AC568
« on: December 19, 2016, 10:52:39 am »
Hi guys,

The 70uf cap is not made any longer as far as I can tell. JJ makes a 80uf and so does F&T.

Any suggestions?

Also has anyone converted  the AC568 back to a Blackface?

Thanks,

Billy

Between fishing, flying, and fooling around with guitar amps, somehow 70 years got behind me. Shorter of breath and one day closer to death as the song goes.

Offline sluckey

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Re: Best replacement for a 70uf filter cap Twin Reverb AC568
« Reply #1 on: December 19, 2016, 11:37:24 am »
Hoffman sells a couple brands of 100µF/350V caps that are ideal for that.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline Ed_Chambley

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Re: Best replacement for a 70uf filter cap Twin Reverb AC568
« Reply #2 on: December 19, 2016, 03:39:45 pm »
With SS rectifier of the Twin, Sluckey's suggestion will work just fine.  Yes, I have "Blackfaced" this circuit.  Really, CBS had not changed a whole lot.  If I am not mistaken, you will still have the 85 watt so when done it should be just like a pre 1968.


A lot of these had the EV speakers installed and will hold a clean quite well.




Offline Planobilly

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Re: Best replacement for a 70uf filter cap Twin Reverb AC568
« Reply #3 on: December 19, 2016, 07:39:53 pm »
Thanks Guys,

It looks like I am the first person to work on this amp. Everything is original. There is very little in this amp that changed from the AB763. I had a couple of 80 uf caps in stock so I only need the 20 uf ones. I have some 100 uf also.
Between fishing, flying, and fooling around with guitar amps, somehow 70 years got behind me. Shorter of breath and one day closer to death as the song goes.

 


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