SOLVED Slide Potentiometers and the 6 Band EQ

[jessemhopkins]

I ordered a set of slide pots for my 6 band eq and the #3 leg doesn't line up with the PCB. I have reached the following two possible conclusions:

1. Slide pot pinout is not standardized and the #3 leg is either across from #1 or #2. If this is the case, then Mouser has failed to provide the option to specify, which makes it seem unlikely.

OR

2. They are supposed to mount on the non-silkscreen side of the PCB. It will fit this way, but if my above conclusion is correct then pins 1 and 2 would be reversed. It would also be unlike any other PedalPCB board that I am aware of, as they all mount the parts on the silkscreen side.

Halp? Thank.

 

[jessemhopkins]

That was easy enough to figure out after thinking about it and a little metering. They do, indeed, mount on the other side of the board.

 

[Robert]

Hmm, I've never seen that before. I used the slide potentiometers from Tayda.

They are supposed to go on the silkscreen side of the board.

 

[Robert]

Just out of curiosity, what part number are those slide pots?

 

[jessemhopkins]

Here's the part. I followed the traces and metered the holes for continuity, I'm positive that they are intended to mount on the opposite site. Maybe a batch had the sides flipped?

 

[jessemhopkins]

You can even see it from my second picture above- look at the pin 2 traces at the top of the board.

 

[Robert]

I'm positive that they are intended to mount on the opposite site. Maybe a batch had the sides flipped?

This is the pot the board was designed for, the pinout is opposite compared to yours.

 

[Robert]

You can see on the product page that the PedalPCB logo normally would be visible when looking into the enclosure. When you mount your pots the logo will be facing down.

 

[Robert]

Actually on second thought, I think those pots might be problematic...

I suspect your sweep is going to be reversed (down for boost, up for cut)

 

[Robert]

I see what's going on.... The pinout of Bourns is reversed compared to Alpha.

 

[jessemhopkins]

I see what's going on.... The pinout of Bourns is reversed compared to Alpha.

Ahhh! That's it exactly. Not only is 3 on the "wrong side", 1 and 2 are also opposite from the Alpha, causing it align correctly to the back of the board. But I see another potential problem- since I will now be mounting the sub-board upside down, I will need to cross the pads for pins 1 and 3, correct? Rather than using straight header pins?

FWIW, I did try to get those Alpha pots but Mouser does not stock them and Tayda is out of stock.

 

[Robert]

You just need to reverse wire the two pads at the bottom of the potentiometer board and it should work properly.

I'll have to take this into consideration on a future revision of the board so it can be easily flipped for Bourns style pots.

 

[jessemhopkins]

You just need to reverse wire the two pads at the bottom of the potentiometer board and it should work properly.

Yep, that’s what I meant. Thanks! Glad we figured it out before I put it together!

 

[zenhunter72]

I was thinking of trying this build. Does anyone have a sample of how you drilled the enclosure for the openings of the slide pots? Just drill a bunch of small holes and file the openings right?

 

[beachbum]

Is it just these 2 wires that need to be reversed?

 

[Guybrush]

I was thinking of trying this build. Does anyone have a sample of how you drilled the enclosure for the openings of the slide pots? Just drill a bunch of small holes and file the openings right?

Unless you are incredibly precise when drilling (or don't mind it looking rough) you're going to need the face plate that is available on the order page.

For each of the sliders you will need to chain drill a series of holes in a straight line. You then place the face plate over the top of this to cover up the rough/wonky edges of the drill lines.

If you don't want to use the face plate then you're probably going to need a milling machine to cut the slots for the sliders.

On a side note, a pillar drill or drill stand will be massively helpful when doing this kind of drilling.

 

[EGRENIER]

How about drilling each ends of the slide, trace a straight line and use a dremel with a cutting wheel to cut the slide ?

however, I’m sure how hard it would be to cut with a dremel wheel...

 

[zgrav]

There was consideration to seeing if Tayda could provide enclosures for this project with the slots. Did that never get finalized?