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Fender Mike Dirnt Road Worn Precision Bass Buzz - Hum Solved

For those of you that own a Fender Mike Dirnt Road Worn Precision Bass and are experiencing 60 cycle hum, I offer up the following experience. I hope you find it useful.

Last week I took delivery of a Road worn Fender Mike Dirnt. It was an open box and discounted $225 so I figured to take a risk, it already being road worn and all, I doubted I would be able to tell the difference anyway...Plus I had been on the lookout for a Tele head stock P bass for awhile.

Boy is it a beautiful bass, fit and finish very nice and a real looker IMO, but it was humming loudly. Louder than usual and for a brand new Fender bass, I was surprised it got through QC. I had read about this somewhere on TB during my research and was kind of expecting it. I noticed it hummed less when I touched the strings but the hum was louder when I touched the pickups. This was totally unacceptable. I knew there was a grounding issue at play here, so I decided to take the control plate off to check things out. I started by check to see if all the wires were connected and when I gently tugged on the bridge grounding wire leading into the whole The ground wire to the bridge pulled out and was not connected! Well, I thought, that explains it. No problem, I took off the bridge, snaked the wire back through and made sure it was making good contact and then buttoned her back up, plugged it in and tried again.

This time it was a lot better but there was still a buzz even when I touched the strings, and when I touched the control knobs the buzz lessened. I thought, well that’s not gonna fly on a gig, especially with the sound man. So I took the plate off again and gave her another look. Upon further inspection I noticed that THERE IS NO GROUND WIRE ATTACHED BETWEEN THE POTS. Look at any P Bass wiring diagram, the pots are supposed to have a ground wire connecting them. I then pulled out the old soldering iron and went to work. I made up my own ground wire, jumped the pots.

Look at the picture and you can see what I'm talking about. I know it's a crappy solder job (I didn't want to overheat the pots) but it's staying in place. Notice there was no grounding between the pots.

Now it is well behaved, virtually silent with both knobs full on and sounds just like any other P Bass should. Mystery solved. All told, I consider what I paid for the bass a steal below $900 and with the Fender HSC included. I hope someone can use this info to fix their bass.


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Fender uses the metal control plate to connect the ground on the pots. However, if they are not making good contact for some reason then the ground is, at best iffy. I normally run a separate ground to the pots myself.

With the bridge, I usually put a piece of copper or aluminum tape on the body under where the bridge goes and put the ground wire on that. That way, if the wire gets pressed into the body it's still making contact with the bridge.

Good work on correcting your issues with that bass. I have never had a Mike Dirnt but always liked how they look.
 
Fender uses the metal control plate to connect the ground on the pots.
...

With the bridge, I usually put a piece of copper or aluminum tape on the body under where the bridge goes and put the ground wire on that. That way, if the wire gets pressed into the body it's still making contact with the bridge.
...
So do I. I go a little further though; I run the tape the width of the screw holes and covering them, I then solder the wire to the tape. The screws have to pierce the tape to be screwed in. I don't know if it improves things or not, but it gives me peace of mind.
 
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