Changing pots soldered to a board?

[Owen]

I am about to plumb Bongo electrics into a MM Stingray. When I say I, I mean someone is for me. This will involve routing for alternative pickups and installing the preamp. I originally thought to put new pots on the pre to move to a 3 pot set up. I looked at the pre this morning and realised that it is pots soldered on to the circuit board. Is this a problem for a competent electronics bod or should I leave it as is?

[itu]

Not very special for a s/he with a decent soldering station and quite a bit of skills.

[ezbass]

Don't worry about that, it's an easy job for a competent solderer with the right tools.

[BigRedX]

If you are only going to have 3 pots what are you going to do about the missing control?

[Owen]

I am looking to vol/bal, bass/lo mid, treble/hi mid. This will fit onto a 3 pot MM control plate + jack socket. I could do 4 pots + side jack. But I do like a jack on the front of a bass. 

[BigRedX]

I see, so you are going to use a stacked pot for the volume and balance. Have you checked that one with the appropriate values (and a centre dent for the balance) is available?

[Owen]

This is part of that process. No point in me thinking about it if the grown ups say that the initial premise is a non starter. I will now go and dig around. 

[basstone]

The usual balance circuit uses a dual gang pot just for the "blend" and I've never seen a stacked pot with dual gangs? Using a single balance control won't give a very smooth blend unless both pickups are actively buffered before the blend control.  Just out of interest why do you need a balance / blend for a stingray?

[Owen]

It is not going to be a Stingray. I am putting Bongo HH pickups and eq in there. 

[LukeFRC]

2 hours ago, basstone said:

The usual balance circuit uses a dual gang pot just for the "blend" and I've never seen a stacked pot with dual gangs? Using a single balance control won't give a very smooth blend unless both pickups are actively buffered before the blend control.  Just out of interest why do you need a balance / blend for a stingray?

oh they exist - this one has a push pull on it too...

https://shop.warwick.de/en/parts-for-instruments/warwick-spare-parts/electronics-parts/20276/mec-volume/balance-push/pull-pot-modules?number=D0813137001564882618A2674-A00000127336 

 

But if you couldn't get them, as the blend seems to be a single gang currently I don't think iy will be a issue

[tauzero]

On 25/03/2023 at 17:36, basstone said:

The usual balance circuit uses a dual gang pot just for the "blend" and I've never seen a stacked pot with dual gangs? Using a single balance control won't give a very smooth blend unless both pickups are actively buffered before the blend control.  Just out of interest why do you need a balance / blend for a stingray?

 

If you look at the photo, the balance is a single gang rather than dual gang pot, although the PCB caters for a dual gang pot. That appears to be for a piezo bridge, looking at the markings on the board. It does mean having a stacked log pot and linear pot combination of the appropriate resistances, preferably with the linear pot having a centre detente.

[Owen]

37 minutes ago, tauzero said:

 

If you look at the photo, the balance is a single gang rather than dual gang pot, although the PCB caters for a dual gang pot. That appears to be for a piezo bridge, looking at the markings on the board. It does mean having a stacked log pot and linear pot combination of the appropriate resistances, preferably with the linear pot having a centre detente.

I am not entirely sure what you just said. But I appreciate that you said it. Would such a pot exist?

[tauzero]

18 hours ago, Owen said:

I am not entirely sure what you just said. But I appreciate that you said it. Would such a pot exist?

 

To expand a bit on that - if you look at the left-hand board, it has two rows of holes for the pot to be soldered two, but the pot used is a single pot (compare with the two pots on the other board which are both double pots). If you look at the left hand board between the pots, you can see

 

 

and the bottom line says that if you have a piezo, you change the single variable resistor to a dual one. That also tells us the value of the blend pot.

 

Whether such a pot exists is another matter. I think it's unlikely.

[Owen]

I have been informed that it was unlikely, but you gave me hope! It was exciting for a bit. It looks like a 4 pot solution instead of a 3 one which is not ideal, but them's the breaks I really do like a front mounted jack socket in a piece of metal.

[Passinwind]

On 25/03/2023 at 10:36, basstone said:

The usual balance circuit uses a dual gang pot just for the "blend" and I've never seen a stacked pot with dual gangs?

https://www.noll-electronic.de/potentiometer/

 

Go to "DOUBLE SHAFT (STACKED) MULTI-FUNCTION."

 

Not an inexpensive solution though. 

[Owen]

I heart Passinwind!

[Matt P]

as this pre uses a single gang pot for the blend in theory it's possible to swap the 2 pots for one stacked pot, they might need to be on wires rather than soldered direct to the board but that's not difficult for a competent tech.

 

Is there a value on the volume pot? the balance seems to be 50K. the link that @Passinwindgave above has a couple of options for stacked pots but only 2 that give a 50K option (50k/500k or 50k/50k, whether they have a centre detent on either pot is not stated.

 

the other thing i would check is that the spacing on the other 2 pots (the tone controls) matches the control plate you are wanting to use, I'm not that clued up on Musicman but there might be spacing differences between the 3 and 4 hole plates.

 

Matt

[BigRedX]

The questions the OP needs to answer are:

 

1. What is value of the Volume Pot?

 

2. What is value of the Blend Pot?

 

3. Does the Blend Pot have a centre dent?

 

4. Will there be enough room in the control cavity for all the circuit boards if the Volume and Blend controls are separate to the boards they are currently fitted to while keeping everything suitably far enough apart so that there are no shorts where the 3 boards could inadvertently touch?

 

5. How are you going to support the Volume/Blend board if it is no longer being held in place by the controls?

[Passinwind]

15 minutes ago, Matt P said:

as this pre uses a single gang pot for the blend in theory it's possible to swap the 2 pots for one stacked pot, they might need to be on wires rather than soldered direct to the board but that's not difficult for a competent tech.

 

Is there a value on the volume pot? the balance seems to be 50K. the link that @Passinwindgave above has a couple of options for stacked pots but only 2 that give a 50K option (50k/500k or 50k/50k, whether they have a centre detent on either pot is not stated.

 

the other thing i would check is that the spacing on the other 2 pots (the tone controls) matches the control plate you are wanting to use, I'm not that clued up on Musicman but there might be spacing differences between the 3 and 4 hole plates.

 

Matt

The Noll 50K/50K pots are definitely detented, as are his standalone balance pots, which are 220K IIRC. There are some custom options available too, but you'd have to ask Klaus Noll directly for the specifics. The last time I heard from him he was still dealing with supply issues, as so many of us have been for the last few years. Prices have gone up radically for the less common formats as well.

 

I'm not familiar with the Bongo electronics package at all, I'll see if I can get a little smarter about that. In many similar situations I've suggested that the customer just go to stacked Vol/Vol and do away with the blend, which I personally rarely like all that much in the first place. But I find all stacked pots to be evil, really. 🙉

[Owen]

I am deeply grateful for you all piling in on this. The vol/vol option is one which would enable me to go for my 3 knobs + jack socket ideal. If all else fails. All the pots will need to be replaced. The tone ones have extra long shafts because of how the knobs are recessed into the Bongo body. Putting knobs on those through a Stingray plate would make them look like mushrooms. 

 

I suspect the control cavity will need to be enlarged and a rear plate put on it. I am too far into the project to back off now!

 

All the pots will be on wires and supporting the boards will be for my (!) luthier to work out. I cannot even put shelves up. 

 

Again, thanks all for your contributions. 

[tauzero]

Changing it to V/V with no blend would need the schematic and somebody who was reasonably expert in electronics to work out how to do it.

 

None of the stacked pots in the link @Passinwind provided would fit the requirements - it needs one undetented log pot for volume (we don't know the value) and one 50k linear centre detented. It looks like there's three which has a mix of log and lin (P1052, P1053, P1056) but the actual values don't match up with what you need.

[Owen]

Ho hum It was exciting while it lasted. 

[tauzero]

It's only one more hole. If you're worried that it might affect the balance, cut the headstock off. 😁

[LukeFRC]

Side Jack and 4 knobs?

[Owen]

45 minutes ago, LukeFRC said:

Side Jack and 4 knobs?

My guess is that I have no option. It would have been nice to keep a front jack socket though. Thank you all for humouring me.