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No Sound from Strings but Pickups 'appear' good....

T

TGN1976

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Nov 26, 2015
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49
#1
Hi All!

I've played some guitar in the past but I'm green on bass and the internal workings of guitars in general. I am making some assumptions based on what I've learned so far reading the forums so please correct me where necessary. Here is my situation:

I bought a used (Bentley?) bass (has a B on the head stock) that I can't get working. I believe it's passive (no battery in the circuit). The strings won't send any sound to the amp, even with a known good cable and bass amp (turned way up). I can tap the individual posts on the pickups and get a loud pop in the amp, which makes me think the pickups are working in some fashion.

I opened her and cleaned everything up, and checked all the continuity and grounds. Everything seems ok there, although the solder joint quality makes the 2M technician in me cringe. They check out nonetheless, and I ensured the ground fed through the body is tightly secured under the bridge. The output jack seems fine as well, since I plugged in a cable and verified the ground to the strings/bridge. I do get continuity from the ground on the cable to the two center posts on one pickup and two outside posts on the other pickup. I don't know of that's good or not.

There are two pickups together on the body, could I have flipped one the wrong way when re-assembling? Could the strings be so old they don't make any noise (don't even know if that's a thing). Also, they don't appear to have the pickup posts lined up with the strings (again, I'm at a loss there).

I'm considering a total rewire job, so I know 100% of the joints are clean, smooth, shiny, concave, and covering. I've read over a lot of good posts here in this forum, but they have caused more questions than answers. Does anyone have a good recommendation or starting point? This is a Christmas gift for a 12 year old, and I'm on a budget so I can't afford a brand new one. If I can get it working, happy times at my house!

Thanks in advance for any help!
 
#2
A starting point..Is it an open output jack, or a long closed cylinder type (the open type are easy to check visibly, the closed cylinder type are notorious)( first thing to check). secondly... put an ohm meter to the 2 pickup leads (resistance on good pickups varies a lot, due to different windings, or even arrangements, it should be between 3.5k and 25k ohms, (aprox.), if the pickup does not have a short, or open due to failed wire) thirdly..wire one pickup directly to the output jack, the pickup ground wire, and the bridge ground should both be soldered to the ground lug, the pickup hot wire to the jack's hot or center lug. with a good cable and amp, you will then know if the pickup is working. (bad strings still make sounds), and with all the other stuff out of the equation, you'll know if the pickup, jack, and bridge ground are working......hope that helps a bit, ...it's a start... post what you find, someone here will read it, and more than likely reply with more help.. Welcome to Talkbass! PS. pickup poles do not have to line up at all for the bass to make sounds)
 
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#3
Growlmonkee said:
A starting point..Is it an open output jack, or a long closed cylinder type (the open type are easy to check visibly, the closed cylinder type are notorious)( first thing to check). secondly... put an ohm meter to the 2 pickup leads (resistance on good pickups varies a lot, due to different windings, or even arrangements, it should be between 3.5k and 25k ohms, (aprox.), if the pickup does not have a short, or open due to failed wire) thirdly..wire one pickup directly to the output jack, the pickup ground wire, and the bridge ground should both be soldered to the ground lug, the pickup hot wire to the jack's hot or center lug. with a good cable and amp, you will then know if the pickup is working. (bad strings still make sounds), and with all the other stuff out of the equation, you'll know if the pickup, jack, and bridge ground are working......hope that helps a bit, ...it's a start... post what you find, someone here will read it, and more than likely reply with more help.. Welcome to Talkbass! PS. pickup poles do not have to line up at all for the bass to make sounds)
Click to expand...

Thanks Growlmonkee! The output jack is an open type, and it's visibly sound (and has proper continuity). For checking the pickup leads, can you specify exactly where I should be testing the resistance? The pickups each have three wires (ground, pot, and to each other). Should I be removing them from the circuit to test, or am I testing across the posts?

I will definitely wire one of the pickups to the output jack once I test the resistance on them; I was just hoping to find an alternative means of testing them first.

Thanks for the reply!
 
#5
David Jayne said:
The fact that you get a pop when tapping the pickups means the whole circuit works as-is. The only two things I can think of that could cause this are : your strings aren't magnetic or there are no magnets installed in the pickups.
Click to expand...

David,

I can see how the previous owner could have installed the wrong strings, but they appear to be regular electric bass strings from my point of view. I didn't know they were supposed to be magnetic - if something metal doesn't stick then should I consider them bad?
 
#7
David Jayne said:
No, that's not what I meant. They must be ATTRACTED to magnets but not behave as magnets themselves. Do the pickups attract steel objects?
Click to expand...

Yes, they do. When I tap on them with a metal tip from a screwdriver set they display attraction (and make the audible pop on the amp). I think I should have known that, but then I am a total noob to this stuff.
 
#9
David Jayne said:
Are the strings extremely far above the pickups?
Click to expand...

They are approximately 1/4 inch. The bridge doesn't have any screws on the top side (closest towards the pickups), so that side isn't flat to the body and therefore lifts the strings up a little. I ensured to wrap the ground going to the bridge around a screw post tightly so it's still good there.
 
#13
What's good here, is people will give you ideas, David chimed in with something I did not think of,..to answer your question on checking the resistance of the pickup coils.....do not disconnect any wires where they attach to the pickups, matter of fact, be careful with those connections. disconnect the pickup wire that's on the pot, and the pickup wire that goes to ground, leave all the wires intact that attach to the pickup itself. measure across the pickup wire that went to the pot, and the one that went to ground, trying to see if the coils are good, or if there are broken, or shorted wires in the windings. If your strings appear to be made of steel, or nickel..they are most likely electric bass strings, if they are metal , but a different color, a picture might help here. if you test the resistance on the coils, those same 2 wires can be soldered to the output jack( one as hot, one as ground, along with the ground wire from the bridge (also to the ground on the jack, that would eliminate the pot from the circuit, 2 things that might get more answers here, and possibly better ones, would be a picture of the bass, showing the pickup configuration, the strings, and if possible the inside of the control cavity. there is nothing so complex in the electronics of a passive bass..that it cannot be made to work, What David said about the strings should have been said first, pics would help a lot, if possible.
 
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#14
Growlmonkee said:
What's good here, is people will give you ideas, David chimed in with something I did not think of,..to answer your question on checking the resistance of the pickup coils.....do not disconnect any wires where they attach to the pickups, matter of fact, be careful with those connections. disconnect the pickup wire that's on the pot, and the pickup wire that goes to ground, leave all the wires intact that attach to the pickup itself. measure across the pickup wire that went to the pot, and the one that went to ground, trying to see if the coils are good, or if there are broken, or shorted wires in the windings. If your strings appear to be made of steel, or nickel..they are most likely electric bass strings, if they are metal , but a different color, a picture might help here. if you test the resistance on the coils, those same 2 wires can be soldered to the output jack( one as hot, one as ground, along with the ground wire from the bridge (also to the ground on the jack, that would eliminate the pot from the circuit, 2 things that might get more answers here, and possibly better ones, would be a picture of the bass, showing the pickup configuration, the strings, and if possible the inside of the control cavity. there is nothing so complex in the electronics of a passive bass..that it cannot be made to work, What David said about the strings should have been said first, pics would help a lot, if possible.
Click to expand...

Got it! I'm going to add some pics in the morning, but I would need fresh strings anyway so I'm going to try that first. That really gives me hope - that it could just be the strings. Either way, I may end up rewiring the thing just so I have that warm and fuzzy that everything is done right.

Thanks again to both of you for all the help so far!
 
#15
Hopefully, it's something as 'simple' as the strings (but I wouldn't have thought of that, right off either). Try any old magnet to see if the strings stick to it.

If it's not the strings, one way to trouble shoot things is to start at the signal source (the pickups) and using a couple jumper wires with alligator clips, connect the pickups to the jack one at a time to verify they each work, and check the resistance of the coils while they're dis-connected. then add components (pots) into the circuit as you solder it back together until something doesn't work, and you'll have found the culprit. By then, you'll be familiar with the workings of that bass, as well.
 
#17
To echo others, I'd bypass the pots and jack.

Leave the pickup where it is,
disconnect both pickup leads from the pots,
use something like alligator clips to temporarily fasten the leads to the + (tip) and - (sleeve) of one plug on a KNOWN WORKING CABLE,
plug the other end of the cable into an KNOWN WORKING AMP, and see if any notes come out.

If "Yes," the problem/s is between the pickup leads and the cable.

If "No," I'd check the orientation of the magnet/s. I really doubt if you'll get no sound since your pickup has already passed the "tap test."
 
#18
You can have inadvertedly got them "upside down". Turn on them. If they're out of phase they will pop when you clonk any metal object to it. The clip test is a tell tale whether it is magnetic or not. If you loosen the strings and the pole pieces or rails will eventually attract the strings towards its top you should hear a pop. I would even try to turn the pickups around, not upside down, but north/South. It can be when both pickups are soldered together they cancel each other. Still a pop will be heard whenever a scredriver or something will be tapped on top of it. Mind you that they still can be magnetic.

TIP:
I have heard of people de-magnetizining and re-magnetizising pickups. But you can't de-magnetize strings. I e run them through a demagnetiziser (or a so called Bulk Eraser). So I would rule out strings. It depends on how your pickups are made and... stored. If they have magnets on the bottom and not pole pieces as magnets. This de-mag thing can happen when you store two pickups too close together for a long period of time. I e using them as magnets and let them cling on together so you can lift up both pickups with one or two fingers just af they were one big chunk of pickup. If they've been laying around in the drawer for years, the magnetism is gone. You may detect a slight pop anyway when tapping with a screwdriver, but it's not magnetic as such. It can be "electric" shortcut or grounding that actually gets heard. But one can't tell the difference between those two pops.
 
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#20
It sounds to me like you've got a broken connection somewhere in the "hot" side of the circuit. Pickups will still make a popping sound if only one side of the circuit is connected. If this were happening with just one pickup, that usually means the break is in the lead-in wire to that pickup, or a break down in the coil. Because both pickups are doing it, it's most likely that the break is somewhere back in the rest of the circuit.

Are you getting continuity from the tip of the jack, up through the hot side of each pickup? Or, is there someplace where you've got the hot side of the circuit shorted to ground?
 

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