Hi All,

Well the Deco build is almost complete but have a hum and dont know if its dodgey soldering (I have de-soldered my last effort & resoldered) or do I need to shield it (single coil pick-up & piezo with blender pot.

Any tips on how to figure out which is the more likely -  would be of assistance.

The hum is there as soon as I plug in and seems to be in the medium to higher frequences.

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Check the grounding. Does it go away when you touch the jack/plug?

-WY

You also need to check and make sure you don't have a ground loop in your wiring. If you run too many ground wires to too many places, you can wind up with a hum. Here is one article with some diagrams.

 

http://alexplorer.net/guitar/basics/grounding.html

 

 

Cool thanks guys. *slaps forehead* I didnt know that you had to ground the strings and I used a rosewood acoustic bridge - so I've just made up a grounding wire from a meat skewer cut down and soldered to some shielding wire. It has reduced it alot but still getting some hum. 

the ground loop thing was interesting. I have all my ground wires to side of the blend pot but at three seperate places not the one point. would this create a problem??  Also if I have the bakelite knob off the pot and touch the spindle the hum reduces.

If the wires are all connected to the back of the pot, but at different places, that should be fine as long as all the ground wires are terminated there, and then the ground wire to the jack runs from that cluster.

 


With single coils, you will probably always have some noise. My Les Paul copy does the same thing with 2 humbuckers. If I touch the strings, the hum goes away. It is louder on some amps, and not so loud on others.

 

Penny Nelson said:

the ground loop thing was interesting. I have all my ground wires to side of the blend pot but at three seperate places not the one point. would this create a problem??  Also if I have the bakelite knob off the pot and touch the spindle the hum reduces.

I have one of those piezo bridge to chinese equalisers, tuners metranome units with the output jack built in. The electric pick up is hooked in through the blender pot.  I will post pics soonish.   The noise has reduced a lot by grounding the string but still there a bit. I have also done some shielding behind the pot.  Thanks for taking the time to look for me.

:D

Dan Sleep said:

If the wires are all connected to the back of the pot, but at different places, that should be fine as long as all the ground wires are terminated there, and then the ground wire to the jack runs from that cluster.

 


With single coils, you will probably always have some noise. My Les Paul copy does the same thing with 2 humbuckers. If I touch the strings, the hum goes away. It is louder on some amps, and not so loud on others.

 

Penny Nelson said:

the ground loop thing was interesting. I have all my ground wires to side of the blend pot but at three seperate places not the one point. would this create a problem??  Also if I have the bakelite knob off the pot and touch the spindle the hum reduces.

Thanks everyone for you help. To assist I have taken a whole heap of pics. I have grounded the strings which made a heap of diference but not got rid of the hum totally.

AAll suggestions to assist in removing hum greatfully appreciated.

I would shield the pup. Just for info, the first thing I always do with new basses is too remove the pick guard and add shielding.

I assume you have a ground going to the case of the pot?

Since you have what looks like a stacked pot, the volume part needs to be grounded to the case.

You might also want to ground the pot case to the jack , in fact , might wanna try that first.

 

 

 

AFKAM

And just for grins, can you disconnect to wire running to the jack, then hook up a wire with alligator clips on both ends, and run that from the ground on the pot to the ground on the jack. That may help isolate if it is a bad connection or not.

Sorry Penny, Not to offend but what the heck is the cross wiring on the pot? You got a loop in there somewhere for sure. So is this the wiring?

 

You might have a loop if so. Here is what I did as a blender. Works good without the hassles.

 

-WY

Also one thing to try is to get some 24-30GA multistrand insulated wire from RadioShack. Makes for easier connections and easier handling.  I see there is a gray wire that is supposed to be the ground wire from the Harrison PU soldered to the case. So how is this affecting the soldered connection on the other side of the case labeled "to Equalizer and output jack"?

 

-WY

Wait, wait, wait, sounds like you got/want this:

 

http://www.stewmac.com/freeinfo/Electronics/Pots/i-4137.html

 

Check your wiring

 

 -- Which is effect is what I do with one pot, so...

 

-WY

Thanks,

The only diff from this pic is that my ground wire is attached to the top connection.

See your other pic (and thanks so much for your time with this) Yellow line to Equaliser & bottom green line to ground.

Would this cause any problems?

If only we had a radio shack here but will try some others and see if I can get some.

The brown wire is from a electronics store and used for board project making so I thought it was the right stuff.

The Grey wire soldered to the board? Maybe you mean the one that leads to the bridge to ground the strings?

Anyway its Monday here so back to work. I will tackle it somemore tonight.

Thanks again for our diagrams helps me get my head around it.

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