DPDT question

[Inflames626]

So some metric pots I bought on Amazon are here: https://www.amazon.com/dp/B09C8G8NH2?psc=1&ref=ppx_yo2ov_dt_b_product_details

They behave a bit strangely in that I think the ground lug is on the left side when looking down on it as you would in a diagram or in a guitar, not on the right.

I think this because whenever I hook it up the volume pot works backwards.

I am wiring these to a DPDT push pull phase switch on the neck humbucker.

I have one more of these (they come in pairs), so when I wire the next one up, I will wire it with the ground lug on the left and the switch lug on the right (I am going to the center lug with the hot wire so I can have an independent volume control that grounds out when turned down).

My question is, if I reverse the wires on the pickup lugs, do I also have to reverse the pickup wires on the DPDT switch?

For example, on a regular DPDT the white Triple Shot wire goes on the left side and the black goes on the right when you are looking at the diagram.

If I reverse the lugs on these weird pots, do I also reverse the white and black wiring on the DPDT switches?

My guess is no since the DPDT lugs are the same on either side, but I wanted to make sure.

I am aware, of course, that I will need to reverse the X shaped wires coming off the DPDT that reverse the phase to the opposite pot lugs.

Thanks.

 

[eclecticsynergy]

Whatever the issue is with the pots may be, IMO you're correct: there shouldn't be any need to rewire the switch.
DPDT push-pulls always work the same - center lugs get connected to either the lugs above or the ones below.
DPDT toggles sometime are three-position, center-on or center-off. But every push-pull I've seen has worked the same way.

 

[Artie]

A pot isn't manufactured with a "ground" lug. You assign it by virtue of which terminal you ground. So, ground the lugs with the green arrows for "normal", guitar/audio operation. Ie, counter-clockwise is volume down.

 

[Artie]

My question is, if I reverse the wires on the pickup lugs, do I also have to reverse the pickup wires on the DPDT switch?

If I reverse the lugs on these weird pots, do I also reverse the white and black wiring on the DPDT switches?

Just to be clear, these are NOT "weird" pots. They are completely normal like I use all the time. Just wire them up as the diagrams show, and you'll be ok. Just be aware of the terminal orientation when you turn one upside down. (Left becomes right. CW becomes CCW.)

Turn that pick upside down and the green arrows on the left are now on the right.

 

[Inflames626]

Thanks ArtieToo . I thought the carbon on the wiper track increased toward a designated ground lug, thereby lowering the volume until it terminates at the ground lug.

So I thought when they made them one end of the C was considered ground because they had to decide which end to coat in more carbon.

I thought these might have been considered "left hand pots," as I've seen mentioned.

Regardless, this is the fifth or sixth time I've done a guitar this way, and it is the only time I've had this happen I think.

Since this is the neck pickup, the pot will be facing the rear of the guitar, while the bridge pickup/killswitch will be facing the opposite direction toward the headstock. So for my purposes the pot will be the one on the right in your helpful image. This would also match the SD wiring diagram when turned upside down, and yet the pot appears to be working in reverse.

That said I'm fairly sure I've grounded the lug you have highlighted, even when accounting for orientation. As it would be in the guitar, this is holding the pot away from me, DPDT pins facing right, CCW to increase volume, CW to decrease.

I've also checked it with a multimeter. 2.1 or so all the way down, 520 all the way up.

The pot is also doing weird things with phase. If the volume is all the way up and the phase switch is turned on (pickup out of phase), there is no output. But if the pot is turned down, signal comes back. However, this means once the pickups are back in phase, there is no output.

 

[Artie]

Thanks ArtieToo . I thought the carbon on the wiper track increased toward a designated ground lug, thereby lowering the volume until it terminates at the ground lug.

So I thought when they made them one end of the C was considered ground because they had to decide which end to coat in more carbon.

There is some truth to that. Pots are generally made with an A, B, or C taper. But they aren't dedicated to a specific grounding scheme. It's common to see the "C" taper used in 3-band tone circuits. (The mid control IIRC.) The pots you linked to are ordinary "A" taper, for log, or "Audio use. To make matters worse, a few decades ago, A and B were reversed. A was linear and B was log. So you have to be careful with NOS pots.

Bourns has some nice charts showing their taper.

 

[Artie]

Rod Elliott has a great in depth guide on pots: https://sound-au.com/pots.htm

 

[eclecticsynergy]

It can be confusing because although standard pots don't vary, some wiring diagrams picture them from the top, while others give a view from the back as you'd see looking into a control cavity.

 

[Inflames626]

An update on this guys: I wired it up according to the SD diagram that has 2 Triple Shots, push/pull phase on neck, and 1 tone. On that diagram, on the DPDT neck pickup the lug on the right side is grounded and the pot is pictured from the bottom as if you are looking down into the guitar control cavity. It is below.

I know the SD diagram is correct because I've wired it this way with other guitars. Yet I've seen other diagrams like on guitarelectronics.com that show the phase switch wired in the opposite manner.

I hooked everything up again, making extra sure that I followed ArtieToo's excellent advice, and I once again got a reverse taper pot on the neck DPDT.

I switched the ground lug from the right side in the diagram below to the left lug. I moved the switch lug from the left to the right (keeping in mind I have this as an independent volume control so the hot wire is going to center lug, unlike the diagram).

After that, everything was fixed. The taper worked correctly. Everything grounded out perfectly when turned down. And the phase switch worked out of phase as expected instead of in opposite taper to in phase operation.

I didn't have to reverse the white and black wires like I thought I would.

Meanwhile the Shadow killpot in the bridge worked normally with the ground lug on the right lug like in the diagram.

The only thing I can think of is these cheap import pots are being made with a reverse taper and are not being marked as such. I consider this a quality control issue. I won't be buying this brand again.

I should have just used Alphas but they were bigger threads than usual and I didn't want to ream out the neck pot hole while the bridge remained metric. The Shadow killpot for the bridge fits metric holes and has a very, very tall shaft. All pots should be manufactured like this because it makes them most versatile for a variety of guitar bodies.

The only downside is it is difficult to find washers and nuts of a small enough diameter to fit them. I have pill bottles filled with screws, lock washers, nuts, and regular washers and it took a lot of trial and error to find a small enough size. Eventually everything gets mixed in with everything else.

So it *was* the pot's fault. For some reason it is reverse tapered. I will have to remember that the next time I work on this guitar or if I use these Micovay pots again.

Once my little Fender belt clip micro amp I will use for test bench work arrives I can verify all this with my ears, but as all I have right now is my Peterson strobe tuner everything seems to be working fine testing with it.

 

[ThreeChordWonder]

Just remember that most circuit diagrams are drawn as though you're looking at the backs of the pots and switches not the pot shafts or switch tip. Imagine you're looking at the back of a strat type pickguard with all the electronics in place.

Also remember:

1. A DPDT push-pull switch connects the middle lugs to the lugs furthest from the pot or shaft in the "push" position, and nearest to the pot ir shaft in the "pull" position.
2. The two sets of three contacts are entirely independent of each other and the pot part.
3. CTS type pots, the ones with the black plastic case in the back work as shown in the image below.

 

[Inflames626]

Thanks ThreeChordWonder . I have seen those new CTS style pots but I'm not sure they're available in metric. I was also concerned how much space they would take in the cavity as they seem somewhat bulky.

I have some old hard wired EMG 89/81tw pickups lying around. The ends are frayed and pretty abused. I plan to put them into a Kramer Assault FR and don't mind reaming out larger holes on that one if needed.

I will probably use these CTS pots on that (OEM-wise EMG and CTS seem to coincide anyway vs. say Bourns for other pickup manufacturers and Alphas for imports).

That way wiring it will be more like a Triple Shot (I'm getting better at that now after 7-8 guitars) and less of a hassle, especially after reinstallations.

I thought if I reversed the ground lugs I would ground out the white (hot) wire during in phase operation and produce no sound.

I see now though that even with the lugs reversed white will go C2 to 4 to 1 then center lug and black (negative) will go C1 to 2 to 3 then to ground.

I thought I would have to switch sides the white and black wires were on since the ground lug was being moved to the opposite side.

I'm still annoyed that I should have to even move the ground in the first place. The taper should work the other way out of the box.

With these pots and the Shadow pots as well I have to clean them with contact cleaner to reduce static at first. They should be clean from the factory.

 

[ThreeChordWonder]

A CTS pot has a 3/8 inch diameter shaft. 3/8ths of an inch is 9.35 mm, so it will fit where a 10mm metric will.

Personally I prefer the Bourns/Fleor/Alpha type myself. More compact and easier to solder up.

 

[Inflames626]

I think most of the pot holes in my guitars are 5/16" or 7.94 mm. I'll have to get my digital caliper and check.