Pickups gone bad - really?

bssist · #1 10-31-2010, 06:27 PM

Hello,

I have found a(nother) hole in my knowledge, and the local "experts" seem to have less understanding than I. Can anyone here enlighten me?

I have a 1990 SR800 that I have been playing since 1991. Over the last 6 months it slowly developed a slight distortion (a cool sounding slight drive that added character). Lately I noticed that it has become full on breakup of the tone when I dig in, and it is very pronounced on the E and A strings. Figuring the preamp was shot I upgraded to the NTMB-918F. Alas the problem is in the pups themselves.

Does anyone know just what is inside that chunk of epoxy? What might have gone bad and why? With no power to them the E/A side rings but the D/G side is dead (on both the P and the J). When the battery is hooked up I get the performance described above (even wired straight to the amp - no onboard controls of any kind).

Can anyone enlighten me?

Thanks!

M0ses · #2 10-31-2010, 06:33 PM

Did you change the battery?

bssist · #3 10-31-2010, 06:58 PM

Yes. Good alkaline battery @ 9.08v. (the fuse is good and it is plugged in, and the power switch is turned to "on" too

).

danomite64 · #4 10-31-2010, 07:36 PM

I have a set of those LO-Z's if you're looking to replace them with stock pickups.

Rockingbird · #5 10-31-2010, 07:41 PM

Well, they ARE just magnets. Heat and impact can cause a magnet to lose its magnetic character, so it could just be that you're playing her too hot and hard.http://en.wikipedia.org/wiki/Magnet#...emagnetization

There's some other gobbledegook reason there too, but I don't understand it.

bssist · #6 10-31-2010, 07:43 PM

Quote:

Originally Posted by danomite64

I have a set of those LO-Z's if you're looking to replace them with stock pickups.

Yes, I really dig the tone they had. How much?

bssist · #7 10-31-2010, 07:50 PM

Quote:

Originally Posted by Rockingbird

Well, they ARE just magnets. Heat and impact can cause a magnet to lose its magnetic character, so it could just be that you're playing her too hot and hard.http://en.wikipedia.org/wiki/Magnet#...emagnetization

There's some other gobbledegook reason there too, but I don't understand it.

Interesting read, I never studied much past the basics of magnetic theory. I did not see anything there that helped me understand what might actually be going on inside that chunk of epoxy. I'm certain it's not a case of just agressive playing unless it's a cumulative type effect. I have had the same attack for years. Actually, I've probably developed finesse greatly over the last few years, so probably less agressive playing than 5 or 10 years ago.

Thanks for the link!

mech · #8 11-01-2010, 06:59 AM

Quote:

Originally Posted by bssist

... it has become full on breakup of the tone when I dig in, and it is very pronounced on the E and A strings.

Does this occur with either PU or just one of them?

Last thing I would suspect are the magnets.

One possibility is that the PU is too close to the strings causing an output from the PU high enough to overdrive the input of the preamp.

I would also suspect a cold solder joint where the PU winding is soldered to the leads. A solder joint that is not great to begin with can degrade over time and can cause distortion. I have no experience with your bass so I can't say if the solder joints are accessible for touch-up.

If the PUs are active (have electronics inside the PU), the electronics could be going bad. This would be non-serviceable since they are epoxy potted.

mech

FunkMetalBass · #9 11-01-2010, 07:48 AM

Quote:

Originally Posted by mech

I would also suspect a cold solder joint where the PU winding is soldered to the leads. A solder joint that is not great to begin with can degrade over time and can cause distortion. I have no experience with your bass so I can't say if the solder joints are accessible for touch-up.

This was exactly my thinking.

Either that, or the angle at which the leads come out is so sharp that the copper inside was already in bad shape, and minor movements over time have forced it to crap out.

maxgrant · #10 11-01-2010, 07:54 AM

I have a 1973 Rickenbacker 4001. About 2 years ago I started taking it out and playing it again after years of using a Spector bass. I played it out for about 6 months and I noticed a tendency for it to feed back, which was unusual. I finally took it into get it fixed after it started howling in the middle of a gig every time I took my hands off the strings. These things just wear the hell out. The explanation I was given at the time was that the windings had come loose and it was microphonic, which I had already confirmed by shouting into the pickup and hearing my voice come out of my bass amp.

bssist · #11 11-01-2010, 10:00 PM

Quote:

Originally Posted by mech

Does this occur with either PU or just one of them?

Last thing I would suspect are the magnets.

One possibility is that the PU is too close to the strings causing an output from the PU high enough to overdrive the input of the preamp.

I would also suspect a cold solder joint where the PU winding is soldered to the leads. A solder joint that is not great to begin with can degrade over time and can cause distortion. I have no experience with your bass so I can't say if the solder joints are accessible for touch-up.

If the PUs are active (have electronics inside the PU), the electronics could be going bad. This would be non-serviceable since they are epoxy potted.

mech

It is both pickups, which has me a bit perplexed. It seems odd to me that the same mechanical failure would happen to both at the same time, but I have seen that before. I pulled them deep into the routs to check string proximity but that had no effect. They had been at the same height for years.

I imagine that they have some sort of electronics inside the epoxy because they require 9v to operate. Actually without the 9v it picks up the E and A strings but the D and G side are completely dead. I don't seem to be able to push it hard enough to distort in this condition. With 9v applied all strings are picked up and also distort when played hard, E and A to a much greater extent. I cannot picture just how the electrons are flowing inside the epoxy and no one has been able to tell me. The local "expert" tried to tell me that they are two coil pickups and that one coil has gone bad in each but I have rejected that explanation. Electronic failure seems most logical to me. I guess I need to just buck up for new pups, but it would be nice to understand so I'm better equipped next time.

Thanks for the input.

FunkMetalBass · #12 11-02-2010, 09:26 AM

What pickups do you have in there? Are they stock? If so, I highly doubt that they are active pickups (you yourself said that you get a signal on one coil all the time, with or without a battery). If it's on both pickups, I suspect that you are having some failure elsewhere.

I'd take it to a different tech and have him diagnose. Somebody here can surely give recommendations. There's only so much we can do without having the bass in front of us.