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The Multi Amp aka Dynalo Mk2


spritzer

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55 minutes ago, palchiu said:

Should be alpha's pot. there.  GB boards with pots?

Is that possible to modify another version to fit mulitple kind of pots? like  4CP601/2500 RK27 as Pot PCB GB's version? Maybe board will longer but more options to fit volume pots.

Anything is possible, but probably not happening. I still haven't figured out what the 4th pin per row is for and the datasheet doesn't seem to define it. I'll have to examine the gerbers for Kerry's board more...

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14 hours ago, Pars said:

Anything is possible, but probably not happening. I still haven't figured out what the 4th pin per row is for and the datasheet doesn't seem to define it. I'll have to examine the gerbers for Kerry's board more...

The data sheet I found says one of the rows is a tap, similar to a transformer tap. In the PCB that row of pins isn't wired to anything.

Edited by cspirou
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I defined a library part for the Alpha 3RP pot and played around with it on the current 3 pot board to see what the pin layout was like. As you can see from the pic below, it might be possible, but there would be some drill overlaps, and the pot would have to be offset 2mm due to the 4 pins per row instead of 3.

Alpha_3RP.jpg

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From looking at Kerry's layout, it looks like he is connecting pins 1 (gnd), 3 (output?) and 4 (input) on the pot. I assume that I am looking at the right pot (Alpha 21mm 3RP-2142G, from Alpha in Oxnard, CA)? There is also a Taiwan Alpha and a Korean Alpha, but the pots I find from there aren't 4-ch, look nothing like this one, etc. :)

The data I found on the CA Alpha company website just shows pins 1-3 on their schematic diagram, so I assumed the 4th pin (right side row) were loudness or unconnected. I also made the assumption that the pin numbering starts from the left lower corner:

13 14 15 16

9  10 11 12

5  6  7  8

1  2  3  4

If anyone has the correct datasheet or a link... this is what I was looking at.

http://alphapotentiometers.net/html/21mm_pot_4.html

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2 hours ago, Pars said:

^ That doesn't match what Kerry did on his boards from L-R top (or front):

1    -    2     -    3     -    4

Gnd  open  output  input

                   (wiper)

 

That's because normally you look at the pins from the bottom. You can't see the pins from the top. We're in agreement.

Edit: actually even flipping it 180 degrees works, it's all a matter of perspective

Edited by mypasswordis
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OK...

Normally, #1 pin is the lower left (which from the bottom would be the upper left, I guess). The "schematic" Alpha has on their website labels the pins 1-3, so I assumed that pin 4 in each row was the open or loudness or whatever pin. I can't find any mention of this on their website, and they don't seem to have complete datasheets. Seems like a typical CA company, with their website and all :)

Where can you actually buy these things, as they have a 1000 pc. min order?

alpha.jpg

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