Blend pot fail :( and pickup selector question

ThePrettyDamned

So today, I finally got around to getting my GSPBASSES PRS alike ready for final set up.  

I put the springs in, I put the nut in (which needs lowering a LOT as it's a brand new blank - hence set up needed!) and I put the wiring loom in.

That was the problem.  It's a wonderful loom by Shugz, and after tightening the nuts, I pushed on my knobs.

First two went on great (volume and tone) but the third didn't! It's a blend pot - and as is the case with many stacked pot type things, the build is apparently not quite so reliable.  The knob went on, the pot was pushed straight out of the back of the guitar!  The pot itself looks to have been damaged as well - the top part is slightly seperated from the bottom.   It is definitely broken - the shaft is no long part of the pot!

So... Plan B.  I'm going to make a new loom - this time, Volume, Tone and a pickup selector switch in the middle probably.  Not half as cool, I know, but whatever.  It also has a mini switch which will be a coil tap for the pickups.  

So, is there a 3 way pickup selector switch that will fit in a pot sized hole?  If not, I'll have to ream it out until one does fit.  

So, I'll be ordering some pots from Mouser soon.  *sigh*.  

The pot itself also looks to have been damaged.  GAAAAAAGH.

ICBM

That's quite common with some pots, including modern CTS ones - there's no circlip or 'step' in the shaft to prevent it being pushed in, and the only thing holding the pot together is the folded-over tabs on the casing, which will open up if you press hard on the shaft. It's usually possible to put them back together and fold the tabs back down.

Standard (decent quality) toggles need a larger hole, yes - 1/2" vs 3/8". You could also use a mini-switch (on-on-on) but that's much smaller and will need a washer.

You can also use a single (not dual-gang) pot as a blend if you use a series blend scheme - this actually works very well, and doesn't have the volume dip in the middle that a dual parallel blend usually does. You need a Linear pot, preferably of twice the value of your volume pot, for this to work best. You will also need separate shield and coil ground connections on at least one pickup.

ThePrettyDamned

ICBM;329056" said:

That's quite common with some pots, including modern CTS ones - there's no circlip or 'step' in the shaft to prevent it being pushed in, and the only thing holding the pot together is the folded-over tabs on the casing, which will open up if you press hard on the shaft. It's usually possible to put them back together and fold the tabs back down.



Standard (decent quality) toggles need a larger hole, yes - 1/2" vs 3/8". You could also use a mini-switch (on-on-on) but that's much smaller and will need a washer.



You can also use a single (not dual-gang) pot as a blend if you use a series blend scheme - this actually works very well, and doesn't have the volume dip in the middle that a dual parallel blend usually does. You need a Linear pot, preferably of twice the value of your volume pot, for this to work best. You will also need separate shield and coil ground connections on at least one pickup.

I could use a wiring diagram but that sounds interesting.

So, if I set my neck pickup for coil tap (not too fussed on tapping bridge to be honest, I asked ash to design the neck specifically for tapping!) and have the bridge as humbuggy only, I could use a 1 meg linear pot as a blend, mini switch for coil tap neck and volume and tone following the blend pot?

If so, I'm doing that for sure!

ICBM

Yes - if one pickup has separate grounds. I'm assuming at least the neck will have if it's splittable, since he will most likely use 4-conductor cable.

If you want to split it, you're probably OK to use a 500K pot - more easily available in 'guitar' styles - to me, it's better to compromise lower than higher with a splittable pickup.

I don't have a diagram, but it's fairly simple:

Neck pickup hot to 'neck pickup off' end of blend pot and to volume and tone pots.

Neck pickup coil ground to middle of blend pot.

Neck pickup shield to main ground.

Neck pickup split to mini-switch; other terminal of mini-switch to whichever of neck hot or coil ground (*not* main ground) shuts off the coil you don't want.

Bridge pickup hot to middle of blend pot.

Bridge pickup ground to 'bridge pickup off' end of blend pot and also to main ground.

Confused yet?

ThePrettyDamned

Okay, I'm following. I think the pickup has a diagram saying which colour is which if not, I'll ask Ash.

So, that allows me both humbuckers or humbucker and single coil, in a blend. Nice

Out of interest, why 500k instead of 1meg? I'd rather not compromise my Bridge rock tone.

If it would, is there a way of using a resistor to change how the neck pickup would respond to a 1 meg pot? Maybe keep a bit of the second coil intact and therefore better behaved with a high value pot?

ICBM

ThePrettyDamned said:

Out of interest, why 500k instead of 1meg? I'd rather not compromise my Bridge rock tone.

500K because the blend pot is in parallel with the volume control, so if you have the single coil selected that will give you an effective 250K volume. A 1M will give you effectively 333K, which might be a bit shrill with a single coil. 1M pots are sometimes a bit hard to get in standard guitar (split shaft, which I'm assuming you need if you have to push the knobs on) pots too.

But if you can get it, 1M will work well too, if you use the second half of a DPDT mini-switch to switch in another 1M resistor across the neck pickup. That will give you 250K when neck split is selected (1M+1M+500K) and still leave the bridge pickup unaffected when the blend control is at that end.

ThePrettyDamned

Okay, I'll use a 500k one and see how it goes. Sounds like it won't really affect the bridge pickup if I understand right.

The switch I have is dpdt, just in case I needed it. I'll use your wiring word diagram when the new pot arrives and let you know how it goes