Low output on middle pickup

pchilson · 01-25-2010, 07:44 PM

Hey,

Have a '93 Peavey Predator strat copy. Neck pickup is fine, bridge pickup is fine but the middle pickup has a very low output.

Using my DMM I can't get any reading on any of the pickups let alone the middle one. I can get readings just fine on some spare MIM Fender pickups I have here. It just won't read at all on any of them.

The output is roughly half of what the neck and bridge pups are. These are the original pickups.

When I install the middle pickup of the MIMs that I have all is well, full output.

I changed all pots and the 5-way switch to rule out bad electronics. Nothing changed, it didn't work right before and still doesn't after the swap.

When the 5-way switch is in the middle position, middle pickup only, the tone pot acts more like a volume pot than a tone pot. The pickup will actually "go quiet" when rolling the tone off.

Any ideas? Could this be a broken winding? If so how does the pickup still work?

pchilson · 01-27-2010, 11:10 PM

No takers on this? Why can't I get any reading on the DMM from any of the Peavey pickups?

uvacom · 01-27-2010, 11:30 PM

How are you taking the reading? Are you on the right scale?

pchilson · 01-28-2010, 01:00 AM

Ohms. You can imagine when I can't get any reading I'm trying all scales to see if I can get anything.
I get readings fine on other pickups but not on any of the 3 Peavey pickups. They all work, the neck and bridge correctly and the middle with much reduced output as stated.

This is a two part question. Why can't I get a reading on any of them and would a break in the winding be a probable reason for the reduced output and if so why does it still work at all?

Thanks

uvacom · 01-28-2010, 03:05 AM

I have no idea why you aren't getting a reading, that's the reason for the basic questions. You don't get a reading even on the highest scale (should be in megaohms)? When I say how are you taking the reading, I mean are you opening the guitar up, are the pickups wired up, etc.?

As far as your weak pickup, my best guess is that there are some shorts in the coil. If there were a break in the coil, it's likely you wouldn't get any signal. But if the coil is shorted somewhere, the turns that are in between the short just don't drive the signal, so the output is reduced.

pchilson · 01-28-2010, 03:26 AM

Thanks uvacom.

When trying to get a reading the pickup is out of the guitar and on the bench. Black probe to black wire and red probe to white wire. I've even put the probes to the thin copper wires coming to the "terminals" and still nothing. When probing the exact same way on the MIM pickups it reads just fine. Mystery 101 eh?

The short sounds plausible. Thanks.

David Schwab · 01-28-2010, 04:11 AM

Quote:

Originally Posted by pchilson

I get readings fine on other pickups but not on any of the 3 Peavey pickups.

Why can't I get a reading on any of them and would a break in the winding be a probable reason for the reduced output and if so why does it still work at all?

They aren't active pickups, are they?

pchilson · 01-28-2010, 04:18 AM

Naw. Just plain old single coils.

uvacom · 01-28-2010, 01:54 PM

It's really strange that you can't measure the DC resistance directly, but there is something else you could try. First, completely disconnect the pickup you want to test from the guitar's electronics, if you haven't already. Try one last time with your meter with the pickup totally out of the circuit, just for kicks. Still get no reading? Do you know Ohm's law? Just in case you don't, it's E=IR (E is volts). If you do, I don't mean to be patronizing. I'm just not making assumptions. Okay, so that means that E/I is R. R is what we want to find.

Get a fresh 9-volt battery, and wire one end directly to one end of the pickup (it doesn't really matter which). Wire the other end to one probe of your DMM, and then wire the other probe of the DMM to the other lead of the pickup - the DMM should be in series with the pickup and the battery. You should have an ammeter setting for your DMM (sometimes you have to move the red probe to a different terminal, and it'll probably say something about that terminal's current limit, in "mA" or "A").

Measure the current (wait a few seconds to give the current a chance to stabilize, as the pickup has a significant inductance), and then divide 9V by the current reading (in mA) that you get. That will give you the approximate DC resistance of the pickup in kOhms.

If you also can't get a current reading, and your meter definitely works (test this procedure on a different pickup as well), then there is almost definitely no continuity in those pickups and it's a wonder that they work at all.

Sweetfinger · 01-31-2010, 02:06 PM

Quote:

Originally Posted by pchilson

When the 5-way switch is in the middle position, middle pickup only, the tone pot acts more like a volume pot than a tone pot. The pickup will actually "go quiet" when rolling the tone off.

Any ideas? Could this be a broken winding? If so how does the pickup still work?

Yes, broken winding. The pickup still puts out a weak signal through the capacitance of the winds. That signal is all high end which is why the tone control now acts as a volume.

01-25-2010, 07:44 PM	#1
pchilson Senior Member Join Date: Jan 2008 Location: Loveland, Colorado Posts: 116	Low output on middle pickup Hey, Have a '93 Peavey Predator strat copy. Neck pickup is fine, bridge pickup is fine but the middle pickup has a very low output. Using my DMM I can't get any reading on any of the pickups let alone the middle one. I can get readings just fine on some spare MIM Fender pickups I have here. It just won't read at all on any of them. The output is roughly half of what the neck and bridge pups are. These are the original pickups. When I install the middle pickup of the MIMs that I have all is well, full output. I changed all pots and the 5-way switch to rule out bad electronics. Nothing changed, it didn't work right before and still doesn't after the swap. When the 5-way switch is in the middle position, middle pickup only, the tone pot acts more like a volume pot than a tone pot. The pickup will actually "go quiet" when rolling the tone off. Any ideas? Could this be a broken winding? If so how does the pickup still work?

01-28-2010, 01:00 AM	#4
pchilson Senior Member Join Date: Jan 2008 Location: Loveland, Colorado Posts: 116	Ohms. You can imagine when I can't get any reading I'm trying all scales to see if I can get anything. I get readings fine on other pickups but not on any of the 3 Peavey pickups. They all work, the neck and bridge correctly and the middle with much reduced output as stated. This is a two part question. Why can't I get a reading on any of them and would a break in the winding be a probable reason for the reduced output and if so why does it still work at all? Thanks Last edited by pchilson; 01-28-2010 at 03:22 AM.

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01-27-2010, 11:10 PM	#2
pchilson Senior Member Join Date: Jan 2008 Location: Loveland, Colorado Posts: 116	No takers on this? Why can't I get any reading on the DMM from any of the Peavey pickups?

01-27-2010, 11:30 PM	#3
uvacom Member Join Date: Nov 2009 Posts: 82	How are you taking the reading? Are you on the right scale?

01-28-2010, 03:05 AM	#5
uvacom Member Join Date: Nov 2009 Posts: 82	I have no idea why you aren't getting a reading, that's the reason for the basic questions. You don't get a reading even on the highest scale (should be in megaohms)? When I say how are you taking the reading, I mean are you opening the guitar up, are the pickups wired up, etc.? As far as your weak pickup, my best guess is that there are some shorts in the coil. If there were a break in the coil, it's likely you wouldn't get any signal. But if the coil is shorted somewhere, the turns that are in between the short just don't drive the signal, so the output is reduced.

01-28-2010, 03:26 AM	#6
pchilson Senior Member Join Date: Jan 2008 Location: Loveland, Colorado Posts: 116	Thanks uvacom. When trying to get a reading the pickup is out of the guitar and on the bench. Black probe to black wire and red probe to white wire. I've even put the probes to the thin copper wires coming to the "terminals" and still nothing. When probing the exact same way on the MIM pickups it reads just fine. Mystery 101 eh? The short sounds plausible. Thanks.

01-28-2010, 04:18 AM	#8
pchilson Senior Member Join Date: Jan 2008 Location: Loveland, Colorado Posts: 116	Naw. Just plain old single coils.

01-28-2010, 01:54 PM	#9
uvacom Member Join Date: Nov 2009 Posts: 82	It's really strange that you can't measure the DC resistance directly, but there is something else you could try. First, completely disconnect the pickup you want to test from the guitar's electronics, if you haven't already. Try one last time with your meter with the pickup totally out of the circuit, just for kicks. Still get no reading? Do you know Ohm's law? Just in case you don't, it's E=IR (E is volts). If you do, I don't mean to be patronizing. I'm just not making assumptions. Okay, so that means that E/I is R. R is what we want to find. Get a fresh 9-volt battery, and wire one end directly to one end of the pickup (it doesn't really matter which). Wire the other end to one probe of your DMM, and then wire the other probe of the DMM to the other lead of the pickup - the DMM should be in series with the pickup and the battery. You should have an ammeter setting for your DMM (sometimes you have to move the red probe to a different terminal, and it'll probably say something about that terminal's current limit, in "mA" or "A"). Measure the current (wait a few seconds to give the current a chance to stabilize, as the pickup has a significant inductance), and then divide 9V by the current reading (in mA) that you get. That will give you the approximate DC resistance of the pickup in kOhms. If you also can't get a current reading, and your meter definitely works (test this procedure on a different pickup as well), then there is almost definitely no continuity in those pickups and it's a wonder that they work at all.

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