P/P Pickup 'Open' ?

Jon Light · From: Saugerties, NY

I am at my weakest when discussing pickups or electronics in general. So I ask things that I should know.

I'm completing a large setup change and clean-up job on an S-10 push pull. New to the owner. It's time to plug it in for the first time.

It is loud but it simply peels paint. But without any body, without the big tone.
I went to my own p/p, a double body 12 string. Yes, it is bright but it's got 'the thing'. Bell tone. Beautiful full sound. Back to the S-10. If it didn't have the sharp thin sound it wouldn't have any sound at all.

I took readings. My 12 string reads around 19K.
This S-10 reads as in the picture.
That needs a rewind, right?

I'll examine the jack and the wiring to make sure there's nothing obvious such as a bad joint or a stray wire strand.

As I consider options to deliver a playable guitar ASAP, I happen to have a reissue BL705 I could pull off another steel. Wide mount.
Would that drop right in, as far as fit, cavity depth etc.?
I know it's not 'right' as far as the Emmons original single coil sound and all. Looking at options.

Jon Light · From: Saugerties, NY

Even though I've read explanations, I remain confused as to how the pickup can still be loud but be defective. But it does not matter that I understand. I just want to make the right call.

J Fletcher · From: London,Ont,Canada

From your description, the pickup needs a rewind or to be replaced . If the coil is open , yes it will still work , though poorly .

Jon Light · From: Saugerties, NY

Yeah. I've read about this many times here on the SGF.

I'm looking to provide the best advice to the owner. I'm so disappointed to not be able to tell him 'come and get it -- it plays and sounds great!'

Dave Mudgett · From: Central Pennsylvania and Gallatin, Tennessee

If the coil is actually open, which it sounds like it is, sound will definitely come out but it will be all treble.

Guitar pickups are generally modeled as LRC filters, where L is coil inductance, R is coil resistance, and C is inter-winding capacitance. C is generally modeled as a shunt to ground, and that is reasonable if the coil is not open because the the effect of capacitance between the source and the output is much smaller than the effect of L and R. However, if the coil is open, it is essential to model capacitance that is in parallel with the coil. What's happening is that the signal passes through this capacitance to the output.

Capacitors are open circuits at DC, but increasingly pass AC signal as the frequency goes up. Thus, those high frequencies pass through to the output, and that's what you're hearing.

This is a good general explanation of how pickups work - https://www.youtube.com/watch?v=7xwTSHo85S0 - an EE course at Georgia Tech. Note that he doesn't model the capacitance from source to output. Again, very reasonable for a working pickup.

Jim Palenscar · From: Oceanside, Calif, USA

The 705's are a bit taller than the original single coils and sometimes require removing the ends of the mounting plate at the bottom as they hit the legs on the pillow(pillar?) blocks- I usually do it on the milling machine. Sometimes you can remove the mounting plate by unscrewing it and simply cut off the ends.

Jon Light · From: Saugerties, NY

Thanks Jim. I encountered exactly this on a different guitar. Had to really mess with the 705 to work around the changer mounting brackets.
I've never had a pickup out of an Emmons and seen what the cavity looks like.

Jon Light · From: Saugerties, NY

So it's not 'night & day'. It's 'not working/working'.
Glad I had this pickup around. It's the only 10 string pickup I had here among a whole bunch of 12 stringers.

I'm glad I had not started messing with the tone control which was doing....something....but sounded awful. Once I realized I needed to replace the pickup I knew enough to wait on the tone circuit. And sure enough, its poor functioning was totally related to the open pickup. It's working as it should (well not quite -- the taper is not good but that will wait until another day).

My biggest frustration is that the springs are too weak in the three-screw pickup height adjustment plate and are not holding the pickup down as low as I want it. I had considered doing something about it but I had a hunch that if I pulled those screws, I would regret it for the rest of my days -- getting in and under to position a new spring and reseat those screws does not look like a soul-calming task.

Greg Cutshaw · From: Corry, PA, USA

I played through an Emmons pickup for many years struggling with the thin tone until I found out that the pickup was open!

Jon Light · From: Saugerties, NY

If I didn't have my own Emmons here for comparison, I'd question my ears. I'd say 'yeah, some guitars are paint strippers'. But that was my first move -- play my guitar, play his....

For the sake of the owner who just got it, needing big setup changes and substantial maintenance so he didn't get much seat time with it before bringing it to me, I'm so glad I found this problem. Otherwise he'd take it home and try to convince himself that this was how it was supposed to sound.

Bud Angelotti · From: Larryville, NJ, USA

Hi Jon- I disconnected my tone control on my P/P many years ago and have not looked back.
_________________
Just 'cause I look stupid, don't mean I'm not.

William Baldwin · From: North Carolina, USA

In my experience, I've ran across more bad single coil pickups than good ones. Of course I'm talking about after they get some age on them. Like 40+ years.
Either I've had them like you're explaining, to where it's all treble, or some that are producing sound, making music, but have experienced some type of failure and only pushing 6ohm. It very common to have to rewind a pickup after they get some age on them.

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