Kramer DMZ-6000 Hum

martybernal · #1 07-19-2009, 03:27 PM

I have a couple of Kramer DMZ-6000's and one of them hums. It hums with all pots turned completely down. All I have to do is turn up the volume on the amp only, leaving all pots on the bass turned down and there is hum. Using the same amp and cord I can plug in my other DMZ and all is quiet. I am wondering if I have an input jack issue? Looking for other thoughts and suggestions. Thanks.

Marty

KramerBassFan · #2 07-19-2009, 04:20 PM

Open the Electronics cavity cover.
Is it shielded with some sort of copper tape?
It very likely is a grounding problem on the bass itself, and not the cord or Amplifier.
How well is it sheilded?
Thanks.

martybernal · #3 07-19-2009, 05:04 PM

Hello. There is no copper tape at all. The only thing I see is the silver looking tape in the bottom of the bass cavity.

martybernal · #4 07-19-2009, 05:07 PM

And I'll be the first to admit. I didn't know a bass that has active electronics would possibly require shielding. I always heard that of single coil bass pickup configurations.

KramerBassFan · #5 07-19-2009, 06:23 PM

Well, to be technical, it is ALWAYS good to have sheilding in a circuit.
Even if it is Active...
And that silver looking tape should have the same effect as copper tape, same purpose, just a slightly different material.
But, have you made sure that the bridge is shielded?

Thanks.

martybernal · #6 07-19-2009, 06:53 PM

The silver tape is in the bottom of the cavity only....no shielding tape in the bridge area. A ground wire does exist under the bridge.

KramerBassFan · #7 07-19-2009, 09:07 PM

Hmm..... How comfortable are you with soldering/wiring the bass yourself?
That seems like the last big choice to me, but I wouldn't attempt it with out experience
(I'm just saying this because I dont know you, and I wouldn't want for you to totally unwire your bass with no clue how to wire it up again.... )

What I would personally recommend would be to unsolder EVERY bit of the electronics, get a schematic, and then rewire it.
The choice is yours.

Thanks.

KramerBassFan · #8 07-19-2009, 09:10 PM

*******Oh, and before you unsolder anything, a DMZ 6000 should be active, so you should try swapping out the battery for a new one.
I would do this before you do anything else, given that it could potentially be a very simple fix, providing that the battery is the problem (if it was nearing the end of its life, etc...)********

Thanks.

martybernal · #9 07-19-2009, 10:11 PM

The battery is new but I can check it. Another thing I noticed is if my hands on off the bass, there is no hum. As soon as I put my hands on the bass, the hum starts. Marty

KramerBassFan · #10 07-20-2009, 06:52 AM

Then it most likely is a grounding problem.
Either the strings, or neck are not grounded well enough.
That's my best bet.

Thanks.

martybernal · #11 07-20-2009, 06:58 AM

I removed the battery and plugged the bass in. And the hum got worse.

Marty

martybernal · #12 07-20-2009, 08:00 PM

I wanted to thank Kramer Bass Fan for all his help and advice. Here's what fixed my problem.

1. Found the ground wire from the bridge on the hot leg of the input jack, moved it to the ground leg.
2. Resoldered all the connections at the input jack, whoever did it last did a sloppy job.
3. Found the black wire to the battery connector half broke, I replaced the battery connector assembly.

This bass is pure quiet now, what a difference all this made.

Kramer Fan thanks for your help and patience. I hope you stick around, you keep the last of us Kramer Player's thumpin and bumpin with our favorite ax....

Marty

KramerBassFan · #13 07-21-2009, 06:27 AM

I'm glad to be of service!
Good to hear that you got your Kramer all sorted out.

Thanks.