Ground hum on 1993 4003.

ajish4 · Post by **ajish4** » Mon Jan 16, 2006 4:19 pm

As I've mentioned in another post, I just picked up a neat 93 4003 player that has VERY HOT pickups.

I played the heck out of it today and noticed a (if I'm using the term correctly) a slight ground hum?

There is a constant LOW static hum on the bass.

If I touch ANYTHING metal, its gone. Ok guys, go easy on me, I'm not the technical type, but it seems to be a ground problem? I checked under the pick guard and all SEEMS ok, can someone point me in the right direction?

I know how to solder and I have a multi-meter, but I'm lost on where to look and how to check for the bad ground, if in fact that's what it is.

Thanks!

ken_j · Post by **ken_j** » Tue Jan 17, 2006 4:16 am

Check the ground to the bridge. It is at the mute I believe.

lars · Post by **lars** » Tue Jan 17, 2006 8:06 am

Check the switch in the mono output jack.

ajish4 · Post by **ajish4** » Tue Jan 17, 2006 9:19 am

Thanks Ken, Lars...

Just what I was hoping for, some specific direction.

I'll check out the bridge area tomorrow so I can spend some time going over the whole bass.

Lars, what should I be looking for in the Mono output jack? The wires look fine, I gently tugged on the connections in the whole area, all SEEMS to be ok. Do you mean it could be the JACK itself?

I'll post the results on the bridge area tomorrow.

Thanks again!

lars · Post by **lars** » Tue Jan 17, 2006 10:55 am

Tony: I don't know if this is typical, but I had a hum problem that I fixed by taking off the strings, pickguard, unscrew the nut of the output jack, pulling it into the body. If you then insert the jack from the guitar cable, you'll see a leaf switch is engaged. Try to clean, even bend the leaf very slightly assuring good contact. If you connect to an amplifier in this stage you can also check if the hum disappears.

ajish4 · Post by **ajish4** » Wed Jan 18, 2006 11:26 am

Just wanted to say THANK YOU Ken & Lars.

It appears the ground was in the mono output jack!

The ground tested fine to the bridge, as well as every other place on the schematic that specified a ground.

Lars, I followed your instructions and cleaned the contacts. I went out and purchased some tuner cleaner from Radio Shack. After bending the leaf to make a better connection, the hum vanished! I played the bass for about 40 minutes, dead quiet!

So strange. Thanks again for the help. I NEVER would have found that myself and it would have resulted in a trip to the luthier.

lars · Post by **lars** » Wed Jan 18, 2006 12:11 pm

Finally, after 230+ posts I was able to make a difference!

ajish4 · Post by **ajish4** » Wed Jan 18, 2006 2:02 pm

Lars:

Not only did you help me out BIG TIME, BUT, your were my 100th post!

I'm now a Senior Member and the only thing I know about Rickenbacker's is that I'm addicted to the darn things!

Thanks to you too Ken, much appreciated!