Weird Grounding Issue with PICS! Please help!

[radiohead860]

So I've got a Lakland Skyline DJ 4 that's had a terrible problem since I got it. I chalked it up to the single coils they slapped in there (Aeros I think). I recently decided to start playing this bass more and would like to play it in my band, but the buzz amplified through my big amp at concert volume was awful.

I replaced the pickups with Bartolinis since and when I did so, I tore apart the bass, looking for worn or loose wires. I taped up one of them that was kinda worn (shoddy soldering from the factoring must've singed the wire). I took the bridge off, checked the contact of the ground wire (which was fine).

I turned down both the volume knobs independently and together and the buzz still existed.

I turned down the tone knob, and the buzz was completely gone. I double checked the contact points of all wires and the solder points look good. This is maddeningly frustrating, I've tried just about everything I can think of...

Any ideas?

Opposite Side Control Plate


Input Jack


Bridge Volume


Tone


Neck Volume


Control Plate

[mcrracer]

Most of those solder connections look like cold joints to me. Especially the wires coming off of the jack. If you know how to solder reflow all of the joints adding a little more fresh solder.

[radiohead860]

Thanks, I'll try that after work tonight. I hope that's all it is! The electronics workmanship is kinda shoddy compared to what I've seen in my Fenders and EBMM... I guess that's where Lakland decided to cut corners because the rest of the bass is wonderfully built.

[Basshoofd]

The three Laklands I had were all soldered properly but this doesn't look so great. A few minutes with the soldering iron should fix it. (While you're at it, change the pickups back to the aeros!)

[radiohead860]

Haha, I liked the Aeros but they were a little too thin in the low-mids/lows for what I need in my band...they may be on the classifieds very soon though

[pbd]

in the third and fourth picture there looks like there could be a wisker of solder or a single strand of wire between the posts on the pot, anyone else see that? Can't really tell if it goes all the way between or not from the pic.

Todd

[fokof]

Check your bridge ground wire. Solder it to a pot frame.

Are your Bartos humbuckers or single coils ?

[mcrracer]

Be careful soldering to the pot case. If you over heat the pot you can easily ruin it. I never solder to the pots directly anymore. I use pot grounding lugs...no chance of damaging the pots.

[lumerino]

check all the grounds continuity with a multimeter, and when you screw the plate back make sure that the pots lugs don´t touch the cavity shield,

if the noise is still there maybe is you have to change the pots

[atheos]

I'd also try replacing the green wire that goes over the tone pot (best visible in pic #4), it looks too tight, possibly compromising some electrical isolation between the wire and the pot. And yes, go through all the joints. Doesn't look too professional soldering.

Could also be that Lakland uses RoHS compliant a.k.a. lead free solder - environmentally safer, sure, but IMHO a lot less functional. Makes soldering more difficult and joints less reliable. If so, I can even remotely try to understand why it looks that sloppy. Yeah, RoHS is mostly an EU thing but I know there are somewhat similar restrictions in some US states as well.

[SGD Lutherie]

Everything looks very oxidized there, and they are relying on the pots touching the foil to ground them. Thats bad news. You are no longer getting a good connection to the foil. It's not a good idea with real Jazz basses with metal control plates either. Run ground wires.

First thing I would do is solder a ground wire from the back of each pot to the next one and then to the jack, which does not have a ground wire!

That might have worked fine when the foil was clean and shiny, but you need solid ground wires. Don't worry about ground loops, because they cannot exist in a bass with a single ground to the amp.

The reason the buzz goes away with the tone knob down is because you are shunting the highs, and that's where the buzz is. The buzz is electrical field noise, and is fixed by shielding, but your shields are oxidized and not being grounded properly.

Just add some grounds and the bass should get nice and quiet.

[mcrracer]

Good catch, didn't notice the foil on this one or the missing ground wire from the jack. I got an excuse...I am blind in one eye!!!!

[MglMatador]

The jack ground is missing? It looks like the black wire that connects to the cable barrel (middle of the jack) just like it should be.

Did I miss something in the picture?

[SGD Lutherie]

Originally Posted by MglMatador

The jack ground is missing? It looks like the black wire that connects to the cable barrel (middle of the jack) just like it should be.

Did I miss something in the picture?

You are correct... the black wire is the ground. I was looking at the wrong lug. But I would still add some more ground wires.

[bassbenj]

Originally Posted by SGD Lutherie

You are correct... the black wire is the ground. I was looking at the wrong lug. But I would still add some more ground wires.

Yes. In addition to reflowing all solder connections: See that black wire that runs down the back of all the pots and goes to the jack? That is the ground wire. You shouldn't rely on the backs of pots being connected to the shaft bushing! They are just crimped on. So I'd also run a ground wire from that ground wire (probably best connected near the jack) to the copper foil on the control plate. Also run a wire from that ground to the copper foil inside the bass body. And finally make sure the ground wire from the bridge goes to the same point (and check to make sure the ground wire is actually making contact with the bridge/strings).

At that point, there should be next to no hum if both pickups are on full. There should be no hum that goes away when you touch the strings or ground. If you have hum when just one pickup is on that doesn't go away when you touch the strings, that is a humbucking problem and has to be dealt with differently (new pups).

[walterw]

i'll differ from the crowd a little here to say that i suspect (between the soldered ground bus and the foil shield) everything to be grounded just fine, and the hum is coming from the pickups. are you dead sure you got a set that is either hum-canceling when together (i.e., one single coil is RWRP from the other) or that they are both hum-canceling on their own, and are both wired properly?

[SGD Lutherie]

Originally Posted by walterw

i'll differ a little here to say that i suspect everything is grounded just fine, and the hum is coming from the pickups. are you dead sure you got a set that is either hum-canceling when together (i.e., one single coil is RWRP from the other) or that they are both hum-canceling on their own, and are both wired properly?

It's not hum, it's electrostatic buzz, because it goes away when the tone is turned all the way down.

[walterw]

well, single coil hum gets attenuated with rolling down the tone knob, too.

electrostatic would go away when he touched it, i'd think.

[SGD Lutherie]

Originally Posted by walterw

well, single coil hum gets attenuated with rolling down the tone knob, too.

electrostatic would go away when he touched it, i'd think.

No, single coil 60 cycle hum is low frequencies and does not go away with the tone control down, since it removes high frequencies.

Electrostatic buzz might go away if he touches the strings, if they were part of the problem. But I think he has poor grounds added to the mix.

I've had this happen and it didn't go away when I touched the strings, but added ground connections fixed it.

[walterw]

well, since we've got the pots and jack bolted to a metal plate, backed with copper foil, and then soldered directly together, i'd be stunned if all three ground routes simultaneously failed.

since the OP is talking about hum so bad he can't gig with it, i still like the pickups themselves as the problem.