Strat 7-way mod question

eru

I have a Strat copy that about a year ago I wired with the 7-way mod using a mini toggle switch. The mod turns on the neck pickup so I can use the neck-middle-bridge and neck-bridge positions. Yesterday I swapped out the volume pot for a new one as the original one was getting a bit scratchy. After finishing soldering I plugged the guitar into my amp and tested the different switch positions by tapping a screw driver on the pole pieces.

I found that when the mod is on everything works as it should. However, when it's off if I tap the neck pickup poles when the selector switch is in a non-neck position (1, 2 and 3) they still output a bit of sound rather than being completely silent. I'm not sure if it was like this before as I didn't test it as thoroughly.

Does anyone know what the issue could be here? (if there is one).

Thanks.

Funkfingers

Photographs of your wiring, please.

eru

Not sure if a photo would be very clear but here's an embarrassingly bad diagram of exactly how I have it wired:  https://i.ibb.co/hCmmWNC/1.jpg

ICBM

Unless the switch is faulty it’s just a bit of magnetic field disturbance affecting the other pickups. You quite often get that with an unnaturally large thump from touching the polepieces with something steel, but it won’t make any difference with the string signal.

Funkfingers

In the diagram, you have connected the centre terminal of the DPDT switch to the volume pot input. It might be better connected to one of the outer terminals. Connect the jumper wire from the selector switch to the centre terminal on the DPDT. This way, in the "off" position, no leaked signal should pass to the volume pot. 

eru

If it's magnetic field disturbance, could there be any reason why it only happens with the neck pickup when the mod is switched off? When the mod is off and the selector switch is in position 1 or 5, if I tap the middle pickup poles there is no output at all. When the mod is on, any unselected pickup I tap doesn't make a noise either. It only happens with the neck pickup (when it's not selected) with the mod off, which is why I thought maybe it could be an issue with my wiring.

(Oops, just edited this post as I got my ons and off the wrong way around).

eru

Funkfingers said:

In the diagram, you have connected the centre terminal of the DPDT switch to the volume pot input. It might be better connected to one of the outer terminals. Connect the jumper wire from the selector switch to the centre terminal on the DPDT. This way, in the "off" position, no leaked signal should pass to the volume pot. 

It's funny because I was wondering if I should connect those wires the opposite way, but that's how it was on the wiring instructions I was following. I'll try changing them tomorrow and see if that makes a difference.

ICBM

eru said:

If it's magnetic field disturbance, could there be any reason why it only happens with the neck pickup when the mod is switched off? When the mod is off and the selector switch is in position 1 or 5, if I tap the middle pickup poles there is no output at all. When the mod is on, any unselected pickup I tap doesn't make a noise either. It only happens with the neck pickup (when it's not selected) with the mod off, which is why I thought maybe it could be an issue with my wiring.

(Oops, just edited this post as I got my ons and off the wrong way around).

In that case it does sound like a slight leak through the switch. Definitely try redoing the wiring as Funkfingers suggested. Also, is the switch frame grounded? If not, make sure it is.

eru

I ended up frazzling a prong on the mini switch with my soldering iron when trying to change over those wires, ffs... Hopefully will get a new switch tomorrow and be back with an update.

eru

ICBM said:

In that case it does sound like a slight leak through the switch. Definitely try redoing the wiring as Funkfingers suggested. Also, is the switch frame grounded? If not, make sure it is.

More or less the whole underside of the pickguard has aluminium shielding on it. Is that enough for the switch(es) to be grounded or do I need to ground the selector switch and/or mini switch to somewhere else?

ICBM

eru said:

More or less the whole underside of the pickguard has aluminium shielding on it. Is that enough for the switch(es) to be grounded or do I need to ground the selector switch and/or mini switch to somewhere else?

It should be enough.

eru

ICBM said:

It should be enough.

Glad I don't have to do any more soldering!

I finally got a new mini-switch today and swapped around the wires as suggested but it still does the same thing. I've decided to just leave it as it is because it doesn't really make any difference when in use and I think it was probably exactly the same before I changed the volume pot.

eru

Not sure if this is related to the above but I've just noticed that with the volume on 0 the guitar still outputs a bit of signal. It took my amp volume to be turned up inadvertently loud for me to notice it. I'm wondering if this could be due to a faulty/poor volume pot (it is quite a cheapo one) or a bad ground connection. If it's the latter then which connection is it likely to be? (with there being 6 ground wires soldered to the back of the pot and one coming from the tone knobs).

ICBM

eru said:

Not sure if this is related to the above but I've just noticed that with the volume on 0 the guitar still outputs a bit of signal. It took my amp volume to be turned up inadvertently loud for me to notice it. I'm wondering if this could be due to a faulty/poor volume pot (it is quite a cheapo one) or a bad ground connection. If it's the latter then which connection is it likely to be? (with there being 6 ground wires soldered to the back of the pot and one coming from the tone knobs).

This is usually caused by the contact between the ground terminal and the trackboard being stressed when the terminal is bent back to solder it to the casing. You can often fix it by squeezing the rivet onto the trackboard with a pair of fine-nose pliers.

All the grounds should ideally be soldered to the volume pot, but as long as the output jack ground and the ground terminal of the pot are, the others don’t matter as much.

eru

Thanks again for your help. I tried what you said with the ground terminal, and also unsoldered it from the back of the volume pot and pushed it back to its original position. I then grounded it again using a short wire this time. However, the volume still leaks a tiny bit so I think I'll probably need to replace the pot. I'll leave it for now though as I'm done with fiddling about with this for the time being, lol.