Foreplay ll, interested in ps cap mod, how to identify 1st, 2nd and 3rd stage

hron61 · 269

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Offline hron61

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I am interested in modding one of my power supply caps with film and maybe doing the bypass at some point but cant for the life of me find info on the three ps caps 1st thru 3rd stage.
Which is which? I feel like a dummy by not knowing.
Im not very good with electronics and im learning some as i read alot of the thousands of posts here from the begining to now but ive yet to come across one that explains which is which.
A picture would be awesome if possible. Thanks.
« Last Edit: February 19, 2025, 11:12:34 PM by hron61 »



Offline Paul Birkeland

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Well the Foreplay II predates the existence of the Bottlehead forum that's not hosted by the Audio Asylum, so I don't think we can fault you for not being able to find this information. 

The last power supply cap is the 220uF/250V cap that's closest to the 12AU7 tube sockets. 

https://www.mouser.com/ProductDetail/WIMA/DCP4G061007ID4KSSD?qs=RB4whv9F6rw7LG5OrQv1Tw%3D%3D

You could probably glue a pair of these to the chassis plate to use in place of the last 220uF cap (use the black RTV available at your local autoparts store). 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline hron61

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Hello and thanks for the info on the ps cap stages.
So, the wima caps sound like something i would be interested in doing next and i think i would prefer that over a bypass.
I read the specs on them and they are quite large indeed but i'll squeeze then in somehow.
I noticed they have 4 leads each, how do they get wired in? Only 2 leads on existing caps.
Again i am learning as i go and value your input and knowledge you provide.


« Last Edit: Yesterday at 01:21:25 AM by hron61 »



Offline Paul Birkeland

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If you set your meter to read continuity, you'll find that there are two pairs of leads that are connected in parallel.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline hron61

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So if im understanding correctly the other 4 leads dont get connected, just left unhooked?
Is magnet wire needed to lengthen the leads or will stranded wire be ok?
Just never seen in person and by the picture on the website it looks like the leads are super short.



Offline Paul Birkeland

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So if im understanding correctly the other 4 leads dont get connected, just left unhooked?
If there are 4 leads on the cap and you leave 4 leads disconnected, then the cap won't be connected to anything... All you are doing with the meter it to check to see which pair of leads are internally connected together inside the cap.
Is magnet wire needed to lengthen the leads or will stranded wire be ok?
I would get some 20-22 AWG solid core tinned hookup wire.  I would not use the magnet wire (it's a pain to work with), and stranded wire is not all that pleasant to work with in situations like this either.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man