Fender P Bass, No Sound

[fcleff69]

I’m too lazy to search so here’s a new thread.

I’m working on a guys p bass. There is no sound plugged in. All the solder points are original and look good. There is a good connection on the output jack. I wiggle all the wires and things are firm and no sound comes.

I disconnected the leads from the pups and put them directly on a live cable. Voila! Sound! So the pups are good.

Cleaned the pots and Jack with deoxit. After retiring the pups, still no sound.

I still need to check the ground wire under the bridge. There is another ground wire in the cavity and it all looks good.

Could the pots be bad?

Jack? Andy?

 

[theothersemioldfart]

bridge ground would make it noisy, not dead.
Even cold solder joints should get intermittent signal while jiggling. Pot could be bad. As an outside chance a shorted tone cap could also kill it but i think that's an unlikely failure.

If you have a multimeter check the resistance across the jack. It should be 6-8k or whatever the pickup is. There has to be a short and it has to be the pot, the tone cap to ground or a wire to ground if everything is connected

 

[fcleff69]

Yeah, that’s what I thought about the bridge ground.

I’ll check the output jack now.

 

[fcleff69]

Seems to be good.

 

[fcleff69]

When I put the multimeter on the volume pot, the negative lead gives me a little scratch through the amp. I get nothing from the tone pot or the output jack.

 

[ponchonlefty]

my kind of thread. is there a good book on this subject?

 

[Andyman]

get a piece of wire & strip a little off each end, ( or if you have one, a jumper with alligator clips) use it to by pass the hot wire across the vol pot, then the tone pot. It would be impossible to fry both pots IMO.

 

[Andyman]

also check the pots with the meter, the center terminal should read resistance between either side terminal, and should change when turning the knob.

 

[Andyman]

ooo, ooo ooo!
ground one meter lead, check all "hot" leads. Compare to leads shorted together.

might have to disconnect stuff

 

[ponchonlefty]

ooo, ooo ooo!
ground one meter lead, check all "hot" leads. Compare to leads shorted together.

might have to disconnect stuff

these pots, are they the same as a speed control for dc motors? or a dimmer switch? you ever take one apart? just a thought. not that it has anything helpful to the subject. it seems dust may be the killer of such control knobs.

 

[Andyman]

these pots, are they the same as a speed control for dc motors? or a dimmer switch? you ever take one apart? just a thought. not that it has anything helpful to the subject. it seems dust may be the killer of such control knobs.

Very similar. low current only, think like a variable resistor.

 

[ponchonlefty]

Very similar. low current only, think like a variable resistor.

would spraying a electronics cleaner fix a scratchy volume pot? or would it short something? i have sprayed the jack before.

 

[Andyman]

would spraying a electronics cleaner fix a scratchy volume pot? or would it short something? i have sprayed the jack before.

if you could spray the right part. it might work it might not. If you can take it apart and just clean the contact surface, you have a better chance.
there is also a chance that the resistive coating on the "disc" or "wafer" (I've heard it called both) is damaged causing the noise.

That said i have disassembled a pot from a 1966 guitar and "fixed" it,

 

[armyadarkness]

my kind of thread. is there a good book on this subject?

No. He usually just asks us.

 

[theothersemioldfart]

Aged Horse is gonna hunt you down if you flood it with cleaner

 

[Jim C]

Aged Horse is gonna hunt you down if you flood it with cleaner

And he wouldn't be wrong.
I've seen guys trash pots with too much of the wrong stuff.
Once you clean out the lubricant from the factory, your screwed.
And make sure you use a 200 watt iron like you would use for copper gutters & roofs...
Having a pair of clip leads makes this troubleshooting take a couple minutes with a meter.

 

[fcleff69]

No. He usually just asks us.

 

[ponchonlefty]

No. He usually just asks us.

i was asking for me. thought there might be a high performance upgrade type book.

 

[ponchonlefty]

if you could spray the right part. it might work it might not. If you can take it apart and just clean the contact surface, you have a better chance.
there is also a chance that the resistive coating on the "disc" or "wafer" (I've heard it called both) is damaged causing the noise.

That said i have disassembled a pot from a 1966 guitar and "fixed" it,

i figured you have. if you gotta buy one anyway might as well see how it works. i like to refurbish old stuff too. the old radio works in the 57. its cool to watch the tubes warm up.

 

[ponchonlefty]

Aged Horse is gonna hunt you down if you flood it with cleaner

i don't know who that is. but he might have a coronary from the way i do things.