[7stringninja]

This is not on my 7-string, but since I am a member, I figured you guys might be able to help me out.

A few months ago I installed a single EMG 81 in my Washburn MG-24 (just an RG-looking 6-string). I took out all of the OEM electronics, the pickups H/S/H, the output jack, the pickup selector, the volume/tone pots, everything.

I then installed the 81 in the bridge position. There are two wires coming off of the pickup itself. They were clearly not long enough to reach my electronics cavity. I extending them using a similar-gauged wire (high quality, used for home/car audio) and soldered the points of connection using a Snap-On soldering iron and using rosin-based solder (the same stuff I use daily at the Car Stereo shop I used to work at).

Being that I have TONS of experience in electronics and wiring/schematics and the such, I had no problem following the supplied directions on wiring the pots and the output jack.

I did have to enlarge the hole that connects the output jack cavity and the electronics cavity (which was the only difficult part of this install).

The problem started when I went to test the guitar. The second I plugged it in and turned on my amp, there was a constant humming. It was the same kind of hum you get if a passive-pickup equipped guitar is not grounded properly. If I touch either of the pots (which has no plastic coverings on them), the hum almost completely disappears.

This lead me to believe it was a grounding issue. So, even though EMG claimed that the pickups did not need to be grounded to the tremolo, I did it anyways, just to try and troubleshoot the problem.

It did not go away, BUT, it did get quieter. The same "fix" applies when wired this way as well. Touch the pots, the hum goes away. When I am playing, the hum is basically unnoticable. Maybe because my fingers are grounding on the strings (like the pots) or maybe because the output of the music is drowning out the hum.

What should I check to try and further diagnose my problem? This is a list of things I've already tested.

1) Resistance on both wires leading from pickup to their terminal points (red goes to one side of the 9v connector - the other goes to one side of the volume pot) - Both resistances gave a very low reading .01mOhms, showing no short

2) Resistance on the 3 wires coming from the output jack (one connects to the tone pot, one to the negative post on the 9v, and one goes to the volume pot) - Once again, these tests all yielded acceptable numbers.

3) Just to be safe, I also tested the resistor supplied with the pickup. 25.34k or something like that is what it tested. Easily acceptable.


What am I doing wrong? Is it POSSIBLE, that the ground on my amplifier might be causing the problem? I just considered that possibility while typing this LONG ASS post. It has never caused problems prior to this, but obviously the method of grounding is completely different on active and passive.

[bostjan]

i have the same guitar (mg-24) and did the same thing you did, except with two emg's instead of one. (later adding emg-s) i had no hum though.

test the same amp with a different guitar and the same guitar with a different amp.

i'd say contact emg. maybe the shielding got messed up somewhere. wish i could be of more help.

[7stringninja]

Originally Posted by bostjan

i have the same guitar (mg-24) and did the same thing you did, except with two emg's instead of one. (later adding emg-s) i had no hum though.

test the same amp with a different guitar and the same guitar with a different amp.

i'd say contact emg. maybe the shielding got messed up somewhere. wish i could be of more help.

(laughing at the idea of contacting EMG)

I've called 100 times and never got an a call-back. The tech is always away.

I use this amp daily with my 7-string (passive pickups) and have zero problems. I have NOT tested the Washburn on another amp though.

Am I wrong in thinking that the EMGs ground through the 1/4" chord, thus grounding through the amp as well? Or because they use the 9v, is the only ground required the negative post on the battery?

[DSS3]

No, EMG's are internally grounded. Sounds to me like you have a bad joint somewhere. Check them all, resolder them all if you have to.

Also, which "2" wires were comming out of the pickup? Did you remember to attach the red to the battery, shield to back of the pot, and white to the far left lug on the volume pot (or switch)?

Do not ground it to the strings... I've known people who have had more hum happen because of this. Even though it seems to have quieted things down, once you find the actual culprit, you'll have to undo it anyways.

Just go over everything, make sure the pots are grounded to eachother, pickups are all grounded to the pots, and the jack is properly grounded to the pots, and from the sleeve lug.

[Digital Black]

Check all your solder connections, you may have a bad joint somewhere. It's possible the EMG is defective. Make sure your output jack is wired properly. Lots of guys mix this up.

[7stringninja]

Ok, I can't explain what I did, but I fixed it.

I wrote down the wiring exactly as I had it, each connection everything.

I took it COMPLETELY apart, and rewired it using the EMG diagram as reference.

I then wrote down the wiring as I had it and compared it to the 1st one. It was exactly the same, but this time it sounds beautiful.

I only have one issue now. When I touch the volume knob, I get a real loud buzzing. Hmmm

[Chris]

Either the ground coming off that pot is no good, or the pot itself is junk.

Edit: Actually, that buzz would probably go away if it was the ground, not get worse. That's odd as hell.