Bugger me, Strat gone bonkers ------ HELP!

merlin

I decided to return my EJ Strat to stock. Simple enough mod, it was just putting the single ply white scratch plate back on. 

All good except that now the pots work in reverse and the middle pickup only works in positions 2 and 4. On it's own there is none.... If it were just the middle pickup issue I would know what to do but the pots?

Any genius help would be gratefully welcomed! 

Sad, from Brighton. 

Funkfingers

Firstly, are you (or the guitar) left-handed?

Secondly, please post photographs of your wiring as it currently stands.

ICBM

That's an odd one...!

Did you undo any of the wiring, or just transfer the loom to the new pickguard?

Funkfingers

merlin said:

the pots work in reverse

In terms of the direction of rotation or in the sense that the lower tone pot now rolls treble from the neck position pickup and the upper tone pot now rolls off the bridge pickup?

merlin said:

the middle pickup only works in positions 2 and 4. On its own, there is none.

On the regular five-way lever selector switch, this can only happen if the little sprung leaf contacts for the middle pickup's terminal have been squished out of shape.

If you have the modern "roller wheel and ridges" selector switch, it is possible that there is a physical obstruction between the wheel and the switch chassis, forcing the lever blade out of contact with the sprung leaf parts.

merlin

Funkfingers said:

Firstly, are you (or the guitar) left-handed?

Secondly, please post photographs of your wiring as it currently stands.

Right handed, both me and guitar. How would that make any difference? 
I'll get it apart and post pics later. 

ICBM said:

That's an odd one...!

Did you undo any of the wiring, or just transfer the loom to the new pickguard?

I changed nothing as far as I was aware, just swapped out the pickguard, keeping everything else in place. 

Funkfingers said:

merlin said:

the pots work in reverse

In terms of the direction of rotation or in the sense that the lower tone pot now rolls treble from the neck position pickup and the upper tone pot now rolls off the bridge pickup?

merlin said:

the middle pickup only works in positions 2 and 4. On its own, there is none.

On the regular five-way lever selector switch, this can only happen if the little sprung leaf contacts for the middle pickup's terminal have been squished out of shape.

If you have the modern "roller wheel and ridges" selector switch, it is possible that there is a physical obstruction between the wheel and the switch chassis, forcing the lever blade out of contact with the sprung leaf parts.

In terms of direction of rotation. 
I'll take it apart again later and have a look to see if there is any obstruction in the roller wheel and ridges switch. I've done this already though...

ICBM

So are the controls completely backwards? ie full up = silence, full down = output? That doesn't seem possible with any fault I can think of.

merlin

ICBM said:

So are the controls completely backwards? ie full up = silence, full down = output? That doesn't seem possible with any fault I can think of.

Yes sadly, that's the case, tone controls operate 1 equals open and 10 equals full roll off, but they do alter the correct pickups, ie rear tone = bridge, front tone = neck. And the middle pickup doesn't function on its own, just in positions two and four. 

ICBM

I think we’re going to need a picture!

Veganic

So only you output socket has been disconnected and reconnected?

Hmmm.

streethawk

Veganic said:

So only you output socket has been disconnected and reconnected?

Hmmm.

Don't need to remove the output socket for a pickguard change. 

Veganic

streethawk said:

Veganic said:

So only you output socket has been disconnected and reconnected?

Hmmm.

Don't need to remove the output socket for a pickguard change. 

Curiouser and curiousler.

Does it quack in 2 and 4 ?

Gagaryn

Your guitar is haunted by a poltergeist. There is no other answer.

Funkfingers

Er, should the stock Fender EJ circuit include a vintage style metal screening plate beneath the pickguard? If so, did you transfer this to the replacement pickguard but, then, omit to reinstate it with the stock white 'guard?

merlin

And fixed. 

I found a wiring diagram that showed a ground wire connecting the pots together. There was none before, but I thought, what have I got to lose? So I soldered two wires between the pots and bingo, it works. Weird because I would have expected to find wires that were there previously in the cavity, but nothing. 

Anyway. I'm back to normal and it's great! 

EDIT; And now thanks to @Funkfingers suggestion, the found and previously stuck screening plate is re-attached and it's back to how it should be! 

merlin

Funkfingers said:

Er, should the stock Fender EJ circuit include a vintage style metal screening plate beneath the pickguard? If so, did you transfer this to the replacement pickguard but, then, omit to reinstate it with the stock white 'guard?

Yes, and I found it stuck to the new, old scratch plate. It's going back on and the soldered wire coming off....

mrkb

Funkfingers said:

Er, should the stock Fender EJ circuit include a vintage style metal screening plate beneath the pickguard? If so, did you transfer this to the replacement pickguard but, then, omit to reinstate it with the stock white 'guard?

Funkfingers wins! What is the prize

merlin

Many thanks to all especially @Funkfingers who SO wins! All good as new and top Strat again! 

ICBM

I’m still baffled as to how this could possibly cause the pots to work backwards and the middle pickup to be silent in the middle switch position but not in 2 and 4... that makes no sense at all.

Leave the soldered wire in place, there’s no reason to remove it.

streethawk

I'm fuming I didn't mention the shield. It had crossed my mind, but like ICBM, was querying how the grounding issue could cause so much madness.

Can we all just pretend I mentioned the grounding plate??

Funkfingers

ICBM said:

I’m still baffled as to how this could possibly cause the pots to work backwards

Without a connection to ground, the tone control components still place a load on their respective pickups. Rotating the pots towards the absent ground connection gradually removes the loading from circuit. (He guessed.)

ICBM said:

I’m still baffled as to how this could possibly cause ... the middle pickup to be silent in the middle switch position but not in 2 and 4... that makes no sense at all.

Agreed. IMO, this has to be a physical issue at the selector switch. 

On the other hand, anything that could short the Middle Pickup Only terminal to ground should still short it out when the selector switch is in positions 2 and 4.

Some vital piece of information is not conveyed in the opening post. Photographs of the circuit in its non-functioning state would probably have provided a simple explanation.

merlin

Funkfingers said:

Agreed. IMO, this has to be a physical issue at the selector switch. 

Some vital piece of information is not conveyed in the opening post. Photographs of the circuit in its non-functioning state would probably have provided a simple explanation.

Quite right, I ought to have taken and posted pics. However, the issue has been resolved.... many thanks y'all (particularly @Funkfingers). And yes, it ought to have been a physical issue at the selector switch, but weird science shows that it wasn't!