[dwagar]

I had to have the P90s in my '53 Les Paul rewound. I sent them to Throbak.

 

[mhammer]

I was unfamiliar with the P13, and can't find any info on them in Dave Hunter's Guitar Pickup Handbook. They look like a slimmed-down version of the P90, but I can't tell if there are two AlNiCo bars abutting a keeper bar, like the P90, or a ceramic bar underneath the keeper, like so many old Japanese pickups. A Google image search isn't really helping, and although Curtis Novak provides some pics of his P13 type, I have no idea of the magnet arrangement he uses, or even whether it is simly his visual take on a P13 and uses a different actual design.

 

[knight_yyz]

double post

 

[knight_yyz]

@nnieman You answered your own question. The braided wire is ground. If you soldered other end of braid to pot there is no continuity. A few strands is not enough. Hard to tell how bad the break is but it looks severed to me. Check continuity between back plate and anywhere on the braid. If it doesn't read zero you need to replace the braid with a second wire, back of pickup to pot. And take a bit of sandpaper and clean off some of the oxidation on the back plate. Measure from the clean spot to the hot. The back plate looks like rotted zinc.

 

[Latole]

@nnieman You answered your own question. The braided wire is ground. If you soldered other end of braid to pot there is no continuity. A few strands is not enough. Hard to tell how bad the break is but it looks severed to me. Check continuity between back plate and anywhere on the braid. If it doesn't read zero you need to replace the braid with a second wire, back of pickup to pot.

View attachment 395398


View attachment 395399

It should not be the issue.
Between + and shielded OP read 0.1 ohms
Answer #25 ; Neck pickup test to .1

 

[nnieman]

I can fix pickups if I had it, to say how by the web to a beginner is another story
Desolder the positif and read ohms at pickup between +post and body

View attachment 395372

What does that accomplish?
Will that show if it’s the wire or something inside the pickup?
I am new to opening pickups so I’m making sure I understand what I am doing.

Nathan

 

[nnieman]

I was unfamiliar with the P13, and can't find any info on them in Dave Hunter's Guitar Pickup Handbook. They look like a slimmed-down version of the P90, but I can't tell if there are two AlNiCo bars abutting a keeper bar, like the P90, or a ceramic bar underneath the keeper, like so many old Japanese pickups. A Google image search isn't really helping, and although Curtis Novak provides some pics of his P13 type, I have no idea of the magnet arrangement he uses, or even whether it is simly his visual take on a P13 and uses a different actual design.

They are in between Charlie Christian pickups and p90s

it’s an alnico bar magnet with a coil around it.
It’s has a bobbin (not wound around the magnet like a danelectro lipstick pickup).

Nathsn

 

[mhammer]

They are in between Charlie Christian pickups and p90s

it’s an alnico bar magnet with a coil around it.
It’s has a bobbin (not wound around the magnet like a danelectro lipstick pickup).

Nathsn

Interesting. Some of the pics show a closed top, like yours, and others show adjustable screws, like a P90. I used to have an old Melody Maker pickup and it was also a vertical bar magnet, plunked in the middle of a bobbin, except that the coil was about the size of a Strat coil, rather than wider like the P13. Thanks for the info. You learn something new every day.

 

[laristotle]

What does that accomplish?
Will that show if it’s the wire or something inside the pickup?

Ah, yes. I didn't think of that.
If the wire is the problem, desoldering (or snipping) will become obvious when taking a reading of the pup.

 

[Latole]

What does that accomplish?
Will that show if it’s the wire or something inside the pickup?
I am new to opening pickups so I’m making sure I understand what I am doing.

Nathan

Read well ; do not open the pickups

If I understand correctly (because the conversation is going in all directions...) you don't know yet if the problem is with the wires or the pickup.

I suggested that you unsolder the positive wire end of the pickup's solder "bubble". Answer #40
This is must to start there

This way the wire and the pickup will be isolated/separated.

Then measure the ohms between the pickup's solder bubble and the pickup's body.
Report

 

[greco]

Read well ; do not open the pickups

If I understand correctly (because the conversation is going in all directions...) you don't know yet if the problem is with the wires or the pickup.

I suggested that you unsolder the positive wire end of the pickup's solder "bubble". Answer #40
This is must to start there

This way the wire and the pickup will be isolated/separated.

Then measure the ohms between the pickup's solder bubble and the pickup's body.
Report

As @knight_yyz suggested in the past, won't cleaning/scraping the solder bubble and some of the back of the pickup and then testing with the with the probes on the cleaned/scraped areas accomplish the same thing?
Doing the above eliminates the potential for the wire being the problem...Correct?
The oxidation could be dramatically influencing the meter readings...Correct?

 

[laristotle]

Doing the above eliminates the potential for the wire being the problem...Correct?

If the short is in the wire, it would still register as a short across +/ - of the pup. Would it not?
Makes sense to disconnect the wire from one of the points of contact, I'd would think.

 

[Latole]

As @knight_yyz suggested in the past, won't cleaning/scraping the solder bubble and some of the back of the pickup and then testing with the with the probes on the cleaned/scraped areas accomplish the same thing?
Doing the above eliminates the potential for the wire being the problem...Correct?
The oxidation could be dramatically influencing the meter readings...Correct?
View attachment 395470

No !

 

[Latole]

If the short is in the wire, it would still register as a short across +/ - of the pup. Would it not?
Makes sense to disconnect the wire from one of the points of contact, I'd would think.

100% right It is the first thing to do.
Too much not helpful answer here........

 

[greco]

Too much not helpful answer here........

OK ...Agreed ...Get rid if the wire as it eliminates it as a source of the problem all together.

However, @Latole you should know very well how much a bit of oxidation can influence meter readings and at least support/ agree to the scraping/cleaning as suggested by @knight_yyz. That is a very helpful "answer"/ suggestion IMO!!

 

[greco]

If the short is in the wire, it would still register as a short across +/ - of the pup. Would it not?
Makes sense to disconnect the wire from one of the points of contact, I'd would think.

You are correct in trying to eliminate the shielded wire as the possible source of the issue.
Personally, I think it is unlikely with braided shield wire but that wire is certainly in rough shape for sure.
I was up much more early than usual and had not had adequate coffee when I wrote that post. How is that for a lame excuse! LOL!

Of nerdy but related interest, I have tried to get solder to soak through the push back cloth insulation of the centre conductor as I often worried that it could happen when soldering the braided shield to the backs of pots...never happened.


Interesting thread!

 

[Paul Running]

 

[knight_yyz]

if the ground was shorted to the positive your reading would be dead zero. 0.1 ohms is not a short!! @nnieman , are you sure your meter rreading was 0.1 and not 0.L? some meters show 0.L as open circuit. 0.1 ohms means something is getting through, like a short with a resisitor bleeding through....

And Latole you are absolutely wrong on the oxidation point made by myself and laristotle. Oxidation and rust affect the reading if you are not making contact. how can you say you worked in electronics field and not know that? If you want a proper reading you want bare metal!!!

I would clean the backplate with a wirebrush or sandpaper, then check for continuity between the ground solder blob and the neck plate for a cold solder joint ( it could also be completly oxidized) I would also check from the neck plate to the farthest end of the braided wire. Should also be zero ohms. Anything higher than zero is a bad ground. If you find the braid wire to be insufficient solder a helper wire from the blob to the pot. Thats assuming the blob has continuity to the plate. If it does not, then solder wick the blob clean the back plate and resolder the blob to the neck plate.

If all that is good then I would think about taking it apart.

 

[greco]

0.1 ohms means something is getting through

Of interest/significance, there was some sound being created when the pickup was attached directly to the output jack.

And Latole you are absolutely wrong on the oxidation point made by myself and laristotle.

I was totally and frequently supporting you on this also.

 

[Paul Running]

if the ground was shorted to the positive your reading would be dead zero. 0.1 ohms is not a short!!

Unless the meter is zeroed, he is measuring the resistance of the test leads...it is considered a virtual short.

Of interest/significance, there was some sound being created when the pickup was attached directly to the output jack.

An open coil can produce an output, depending on the number of windings in the continuous section , the coil will produce an audible output through stray magnetic induction.