Issue with '73 Jazz Bass pickups...

[Alper Yilmaz]

Hi,

I have a '73 Jazz Bass which I bought few years ago upon consulting with buddies here on the Forum for authenticity. It sounds and plays great!

Recently, though, there has been a considerable decrease in the bridge pickup volume. First, I thought it could be from the pots and used some contact spray to clean all three of them, but it did not help much. I do not want to change the pickups and the pots without further checking if everything is alright, since I want to keep the bass as original as possible.

So, here is a set of questions:

- What could be potential problems with the pickups? Can they die out of the blue? What is the remedy?

- Is there a way to measure the output of the pickups without unsoldering them from the volume/tone controls?

I would appreciate any input. Thanks in advance. Best,

Alper

 

[Grissle]

You'll need to unsolder to test.

 

[narud]

You can still test the dcr while its soldered to the pot. And yes this era of pickup can die out off the blue. The insulation on the wire can wear off and short against the magnet.

 

[vistacruiser]

First the obvious, since you didn't say if you checked this.
Did the pickup height change? Old foam deteriorating under the pickup, or just being stuck down on the screws is the most likely.

I use a digital volt meter to check and balance the output between pickups. Set your meter to a/c mV (milli-volts). Clip the leads to an unused 1/4 inch plug or the end of your instrument cable and plug into the bass. Pluck the strings as evenly as possible and compare voltage levels for one pickup to the other. The volume should be up for the one you are checking and off for the other. Tone should be up for all tests.

It's normal for a Jazz to see slightly higher output from the neck pick up, but you can raise the bridge pickup to equal it if you like. I normally see levels in the .050 to .100 mV range, some times as low as .035 or as high as .150 mV. There are variables of course, the way you pluck has a lot to do with it as does string height, so the idea is to use this data to balance the pickups output with height adjustments. If you have the height set a little closer to the strings on the bridge pickup and still very weak output in comparison the the neck, then you may have a pickup problem. Could be a wire lead about to break off at the solder connection.

By the way, while you have the meter plugged into the jack, you can read resistance in the windings the same as if you had un-soldered the pickup. Set meter to ohms and turn vol up on the pickup you want to read and down on the other.
Hope this helps you test with out removing your pickups.

 

[Alper Yilmaz]

Thanks for the input, folks...

The pickup height is still the same; no change there.

I will test the output voltage and the resistance in this case and see if there is anything weird going on in between the two pickups.

Best,

Alper

 

[jphilauren]

Had similar problem my neck pickup had a decrease in output. Windings were fine no corrosion.
After some research the pickup was losing its magnetism . They can be remagnetized, but I decided to replace both pickups with Aguliar 70's
Sound great, I will eventually repair the original pickups. Fender of the 70's is a crap shoot , 50% chance either good or bad

 

[Alper Yilmaz]

>Fender of the 70's is a crap shoot , 50% chance either good or bad

Exactly! Also, even though I am positive about the authenticity of all other parts, I cannot even tell the origin of the pickups on mine. The soldering points look authentic, but maybe I should do the same (going for Aguilars or Fralins) at one point.

 

[Tom Cileski]

The neck pickup on my '75 Jazz died. Sent it to Lindy Fralin and it came back rewound to perfection.