Strange Buzz

[Richard]

I have a 2014 Les Paul Melody Maker with Dimarzio Virtual p-90 in the neck and DLX Plus in the bridge. I recently noticed a staticky buzzing sound with the neck pickup, regardless of which coils I have selected. It sounds electrical, if that makes sense (not string buzz) and seem most intense at the 7th fret E on the A string. Before I pull this sucker apart can anyone suggest ways to home in on the problem quickly or any likely causes to investigate? Thank you for your help!

[big_teee]

Have you checked all your grounds, & Pots?
I like to turn the vol. pot to max, plug a cord in and check the pickups with an ohm meter across the plug.
Then switch ro the other pickup, split the coils, switch to dual pickups parallel, etc.
From the sleeve of the cord, check ohms to all the grounds, bridge, switch, pot backs, etc.
If that doesn't find anything, then I guess check the pickups?
GL,
T

[Richard]

All the DC resistances seem normal. This isn't like the 60 cycle hum, it only happens when I play the note. It is less noticeable in humbucker mode. I'm suspecting a bad solder joint but I'm hoping to have a more targeted investigation if possible.

[big_teee]

That's strange, just one note.
Like you said not the fret, but it goes away when you turn down the volume?
Doesn't change at a different distance from the amp, or turned different?
Does this have regular pots, or does it have the gibson circuit board.
Could it be something vibrating at a certain note frequency?
That sounds like a good one!
T

[Richard]

I had a similar issue with and amp with a bad solder joint, the contact was intermittent due to vibrations. Well, it's most prominent at that note and when I play it harder, almost like when something contacts a speaker cone and the buzz goes away as the note fades. I probably don't have any choice but to open the guitar and touch up the solder. Since the noise doesn't seem to be affected by the series/tapped/parallel switching maybe I'll start with the selector switch and volume and tone control.

[pdf64]

I would start with verifying that the bridge grounding is robust; that's the connection that would be most susceptible to being affected by string vibration, and it's often just a 'pressed' joint that oxide / gunk might interrupt.

[Richard]

Problem turned out to be pickup selector, a little sandpaper on the contacts and it's all good.

[Chuck H]

I "liked" the post because you were able to hear what was happening and narrow it down impressively quick. But...

I wanted to mention that sanding the selector contacts is probably not the best solution. Just cleaning them with a deox agent would be better. Contacts on switches like that are often plated. Sanding just removes that more quickly and exposes an unplated material which is usually more prone to further oxidation. Also, the nice, shiny surface that the sandpaper leaves isn't actually that smooth. Less actual surface material leads to faster wear and the fine striations in the surface can hold more contaminants that can cause further oxidation or dirty contacts.

It's good the guitar is working and great that such an obscure problem is resolved. That sort of thing could drive a guy mad if he didn't figure it out. JM2C but I would probably order a new switch if it were my guitar. Just to feel good about it.

[Richard]

Good point about wearing down the plating on the contacts and leaving scratches. I probably used at least 400 grit, maybe 1200, D5 didn't do the trick. The guitar's is 2 years old so hopefully the switch will hold up for a while. I'm just glad I didn't have to go through the push pull switches to get to the bottom of it. The output was intermittently pretty low a couple of times and I bumped the switch and it cleared up, that's what helped me figure it out. Now I just need to fix the nut and get the bridge pickup to stop squealing.

[Leo_Gnardo]

Good point about wearing down the plating on the contacts and leaving scratches. I probably used at least 400 grit, maybe 1200, D5 didn't do the trick. The guitar's is 2 years old so hopefully the switch will hold up for a while. I'm just glad I didn't have to go through the push pull switches to get to the bottom of it. The output was intermittently pretty low a couple of times and I bumped the switch and it cleared up, that's what helped me figure it out. Now I just need to fix the nut and get the bridge pickup to stop squealing.

Lotta diff between 400 & 1200 grit. Let's hope it's the 1200 you used - for switch contacts I've done similar, just 1 or 2 swipes and for extra points with D5 soaked into the paper. 400's pretty rough for this purpose, I'd only use that if it was do or die, gotta make it work for a couple gigs then def. replace the switch. In any case score a working guitar for you, and think about getting a replacement switch so it's handy if the one in the axe gives you any further grief.

Heat up the wax pot, looks like your bridge p/u is heading for a dipping party. Snoop around here, I'm sure there's some info here on how to do it successfully. Be aware that metal pickup covers can be the culprit: now I do my wax dips with covers on. Warming the pickup prior to the dip can help wax find its way deeper into those tiny crevices too.

[Richard]

I think I need to check the mounting, placing my fingers on the pickup kills the squeal, maybe it's a little more of a howl. Aren't microphonic pickups usually very high pitched? It's a DiMarzio DLX90 screwed directly to the metal pate screwed to the body. Because if the tight clearances I had to move one of the 2 screws so part of the plate is not as firmly attached. Hopefully potting isn't necessary, I think I have some beeswax if it is.

[Chuck H]

Try replacing the mounting springs with carefully sized surgical tubing Eight out of ten times that'll fix it if physically damping the pickup stops the noise.