Intermittent pickup failure, help!

[tgv1975]

The (long) introduction, for context:

I have a dual humbucker guitar (Jazz Neck/JB Bridge), wired with a Fender 5T4P superswitch, one volume, one tone. This is the schematic: http://www.seymourduncan.com/suppor...atics.php?schematic=2hum_1vol_1tone_super5way

I altered it by splitting to the outer coils, also shorted pins 2 and 4 on the second stage, so that in position 2 (counting from bridge), instead of the split bridge only, I have the full neck in addition to it. I use a .022uF capacitor. I use push pull pots that each split one humbucker to the inner coil, in any position.

This is the second full revision I've done on the electronics, now using Bourns pots (Alpha before that), and the superswitch (had the factory megaswitch before that).

The problem:

When in position 5 (counting from bridge) = full neck humbucker, sometimes there's complete silence OR a very, very, VERY faint signal.This occurs 1 out of ten times I switch to position 5. Now, the weird bits: all other positions involving the neck work just fine; the problem it sorts itself out spontaneously after a while; every time I open the control rout, by the time I use the multimeter it seems to be spontaneously resolved; this exact same problem happened with the first set of electronics, too! Which makes me think there's a problem with the neck pick-up somehow. But it keeps on working on the other positions...

This is obviously driving me crazy. I ruled out some treacherous intermittent contact between wires/pins with the shielding surface, I checked all the wires and solder joints. The switch is brand new (the same problem happened with the other switch, anyway). As I cannot reproduce the problem at will, it'll occur on its own timing, whenever it wants, and sorts itself out mysteriously, I am unable to investigate thoroughly using measurements.

So, do I need to keep looking elsewhere for this phantom problem, or is there a chance that my neck pick-up is bad? I don't know, some sort of problem inside it? Maybe just one of the coils? So that it keeps working in combinations with the bridge? Anyone heard of this before?

Many thanks, any help much appreciated!

 

[GuitarDoc]

Re: Intermittent pickup failure, help!

What guitar is this in? Is it a Fender type with the controls on the pickguard or a LP ty with controls on the guitar body and a separate control cover on the rear?

If it is the latter, does it do this if you leave the control cover off? Or only when it is screwed in place?

 

[tgv1975]

Re: Intermittent pickup failure, help!

In a Schecter Custom Classic, a Les Paul-type control route. With it off, the problem still occurs. I thought it was some pin touching the shield on it, but apparently that's not it.

 

[GuitarDoc]

Re: Intermittent pickup failure, help!

Well, if it only works in position 5 (neck only) then it has nothing to do with the pup (it would also misfunction in position 4 and 3). So it can only be the solder/wire connection to the lug #5 on the switch, or the lug itself on the switch may be broken, or the contact within the switch may be bad. If you've tried resoldering that connection and are sure it is good, then a new switch is in order.

 

[tgv1975]

Re: Intermittent pickup failure, help!

This is a brand new switch. Had the same problem with the previous wiring. Seems so strange that I'm getting more or less the same problem with a full overhaul of the electronics (changed switch, pots, cap). I do have a 160K resistor between lugs 1 and 2 of the volume, just to mention it, but I don't think that's related, it's the same for all positions.

 

[scottish]

Re: Intermittent pickup failure, help!

you never hear any difference in position 2 which also has the full neck? if all the other positions involve the split neck then it could be a faulty pickup with something funky in one of the coils. Im assuming that you are totally confident in the alterations you made to the wiring because i dont know jack about superswitches.

I agree its unlikely to be the switch since this is the second one but i had the same problem on a strat with my neck single coil being funky. Sounds like the exact same problem and i went through 4 switches before it stopped happening. After i changed everything once it was still happening so i must have checked solder joints and wiring a million times and couldnt find anything wrong. At that point i decided it must be the switch and ordered a few more. Took to the fourth one until i stopped having problems.

Albeit i wasnt using super high quality switches, i think the ones from stew mac. It drove me crazy though and i think the odds of this must be pretty low.

 

[tgv1975]

Re: Intermittent pickup failure, help!

No, there's no difference in position 2! The switch is a Fender original part. I am confident everything was wired right. When it works (which is most of the time), it works flawlessly. Not being able to reproduce it at will (so I can test it) drives me nuts! Your experience only adds to the weirdness of it all Thanks for letting me know I'm not the only one.

 

[constant mesh]

Re: Intermittent pickup failure, help!

What switch is it? Is it a regular Fender type blade switch with two rows of poles or a Superswitch? If yes, check that the screw on which the lever revolves is tight if equipped. You can put some loctite on there, won't hurt. Most screw-type loosen themsels over time from repeated motion and that can cause shorts in #1 and/or #5 pos.

If it's a rivet type it might be shorting out by travelling past the points for #1 or #5 position. This might be a pickguard slot issue too, especially with cheap switches. Some switches like cheap Megaswitch copies are notorious for jumping out.

 

[scottish]

Re: Intermittent pickup failure, help!

What switch is it? Is it a regular Fender type blade switch with two rows of poles or a Superswitch? If yes, check that the screw on which the lever revolves is tight if equipped. You can put some loctite on there, won't hurt. Most screw-type loosen themsels over time from repeated motion and that can cause shorts in #1 and/or #5 pos.

If it's a rivet type it might be shorting out by travelling past the points for #1 or #5 position. This might be a pickguard slot issue too, especially with cheap switches. Some switches like cheap Megaswitch copies are notorious for jumping out.

Even if thats not the case, that sir, is good to know

 

[BlueTalon]

Re: Intermittent pickup failure, help!

What switch is it? Is it a regular Fender type blade switch with two rows of poles or a Superswitch? If yes...

This cracked me up!

 

[tgv1975]

Re: Intermittent pickup failure, help!

What switch is it? Is it a regular Fender type blade switch with two rows of poles or a Superswitch? If yes, check that the screw on which the lever revolves is tight if equipped. You can put some loctite on there, won't hurt. Most screw-type loosen themsels over time from repeated motion and that can cause shorts in #1 and/or #5 pos.

If it's a rivet type it might be shorting out by travelling past the points for #1 or #5 position. This might be a pickguard slot issue too, especially with cheap switches. Some switches like cheap Megaswitch copies are notorious for jumping out.

It is a Fender original part Superswitch, as stated in the OP. Very interesting points! I'll check it. However, I cannot reproduce it at will, I would assume I could, if this was the problem? Thanks a bunch for your suggestions!

 

[Scott Miller]

Re: Intermittent pickup failure, help!

Position #3 on that diagram should be both humbuckers full (not split). Are you getting the full neck pickup in that position?

 

[tgv1975]

Re: Intermittent pickup failure, help!

Position #3 on that diagram should be both humbuckers full (not split). Are you getting the full neck pickup in that position?

Yes, I do.

 

[Scott Miller]

Re: Intermittent pickup failure, help!

Then the pickup is fine. There is either a problem with your switch, or with the wiring TO the switch in that position.
Can you post a picture (or two) of the switch wiring?

 

[GuitarDoc]

Re: Intermittent pickup failure, help!

Then the pickup is fine. There is either a problem with your switch, or with the wiring TO the switch in that position.
Can you post a picture (or two) of the switch wiring?

Exactly! It can't be the pup. Scott knows pups as well as anyone can.

Even if it is a new switch, that doesn't mean it can't be defective. But that still doesn't rule out operator error (bending/weakening the switch lug during wiring; getting that lug/switch too hot while soldering; shorting out against another wire or the cavity wall).

 

[tgv1975]

Re: Intermittent pickup failure, help!

It's a relief to know the pup is unlikely to be faulty. I don't know if I'll be able to do the pictures, but I'll definitely have a long, hard look at the wiring and soldering. What puzzles me, though, it's the intermittent nature of the fault, and the inability to measure/reproduce it. The switch seems to be more and more the culprit. Another potential red herring here is the fact that this happened with a completely different set of electronics, that's what made me think the pup was faulty, as it remained the constant through the electronics overhaul.

Thanks again, I guess I'll just have to mess with the switch and keep on digging. Will try to post some usable pics.

 

[tgv1975]

Re: Intermittent pickup failure, help!

I just noticed the same problem on the bridge pickup, but only just once. Another really, really strange thing I discovered is this: when the neck PU position 5 goes silent as described above (all other positions continue to work), if I unplug the cable from the processor, short the T and S with my fingers, and plug it back in, get this, position 5 works again!! This is mind numbing. I have no idea what the hell is going on. It can't be the cable, all the other positions work...

Any other ideas for this crazy situation? I feel I'll be going crazy. Some esoteric voltage/impedance thing I don't know about?

 

[tgv1975]

Re: Intermittent pickup failure, help!

Just an update, to wrap this up.

I am now 99.9% confident it is the volume pot, namely the push-pull part of it - it's the one that splits the neck pickup! During an episode of "neck silence", I accidentally hit the volume pot with my hand, sort of force-pressing it down - that brought back the sound. Then every time this happens I fiddle a bit with that pot, and I get sound again.

Since this is a rather complex wiring (5-way superswitch, plus two push-pulls), it took a while, but it now makes complete sense. Of course the pot failure to open the split circuit in pushed position (basically to disconnect the red+white wires from ground, while the green is grounded, hence failing to close the GROUND->green->red+white [remained grounded, signal lost here]->black->HOT in the neck position = full humbucker) allowed the split positions to work (as if the pot was pulled), but silenced the full position.

The moral of the story: as per usual, nothing esoteric at play, just simple stuff, but hidden in a complex circuit, plus the unfortunate coincidence of using two (!) consecutive faulty pots (unless it is my fault by overheating them, or something, although I doubt it) - this may be a lesson for buying them off ebay (even if new).

Thanks for all your help!