Weird Pickup Problem - Strat

[Andy M]

So I have this late 80s Strat which has been modified over the years.

First (a long time ago), I swapped out the original pups for a set of Fender Custom Shop 54s. Nice.

Then, much later, I decided I wanted a fixed, hard-tail bridge, so a guitar builder friend of mine modified the body and fitted a Gotoh brass bridge. Even nicer.

A while later, the middle pup stopped working. I removed it and tested it. Nada. Zilch. Dead. Took it to a guitar tech for a second opinion who told me he could re-wind it but it would have been expensive and may not have sounded the same.

So... I decided to move the bridge pup to the middle position and install a Seymour Duncan JB Mini Humbucker in the bridge slot. Fantastic..! Perfect. Finally I had found the guitar I'd always wanted but hadn't know it.

Now here's the weird bit...

Lately, very occasionally, the middle pup stops working. Not during play, but after the guitar has been left for a day or two. I must stress here that it doesn't happen often.

But it gets weirder...

If I test the pup with a multi-meter, it starts working again

Yeah, I know...

And it will keep on working fine for weeks, months, until it decides to screw with my head again.

Then, out comes the meter to check resistance and hey presto, it works again.

Why would testing with a multi-meter make the pickup work again..?

BTW, I have checked the switch and all the solder joints, and everything is fine there.

Any advice is welcome.

 

[hamerfan]

Switch randomly cuts out in the middle position.

 

[Andy M]

Switch randomly cuts out in the middle position.

Thanks for your reply. However, I have checked the switch and it's fine. Besides, when this happens, the pickup doesn't function at the in-between settings - pos 2 & 4 which means it's not the switch.

It also doesn't explain why a multi-meter test fixes the problem temporarily.

 

[hamerfan]

The contact surface is oxydated and generates high resistancies on low voltages. Your multimeter works with a 1000 times higher voltage.
A contact cleaner might help.

 

[GuitarDoc]

Very simply...you have bad solder joints. They may LOOK good, but they are not. The contacts on the switch may need to be cleaned as hamerfan suggests, but that may be a coincident problem with the bad solder joints.
Re solder all of the connections on the switch and pots and jack. If you know how to solder well, this WILL fix your problem.

 

[Mincer]

Very simply...you have bad solder joints. They may LOOK good, but they are not. The contacts on the switch may need to be cleaned as hamerfan suggests, but that may be a coincident problem with the bad solder joints.
Re solder all of the connections on the switch and pots and jack. If you know how to solder well, this WILL fix your problem.

This is my thought. It isn't strange that a guitar with mods over 30 years old would have some issues, especially if we weren't great at soldering when we originally performed them. I'd just go over all the connections one more time.

 

[Andy M]

Thanks for the replies. I will take your advice and re-solder all the joints and clean the switch as soon as I can.

Thanks again to all of you