Need help identifying ground issue

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bttf
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Joined: April 1st, 2018, 4:10 am

Need help identifying ground issue

Post by bttf » April 1st, 2018, 4:19 am

Hello,

My Ibanez Iceman has had a noisy hum for a while, and it seems to be because of a faulty ground connection.

Recently I opened it up and took my multimeter to it. Using the connectivity sensor, it seems that the ground connection is good between 1) the pots 2) the toggle switch 3) and the pickups

Where else can I look? I'm not sure where the leak is coming from.

I'm also not sure if I'm checking correctly. I've basically attached one end of my multimeter to the ground tip of the guitar jack, and have been touching the 1) back of pots 2) the one soldered tip on the toggle switch that seems to be ground 3) the back of my pickups, all of which signal that there is a connection

Thanks in advance

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Musicus
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Joined: November 22nd, 2017, 10:52 am
Location: Nashville TN

Re: Need help identifying ground issue

Post by Musicus » May 5th, 2018, 8:32 am

An ohmmeter won't really show you shielding problems. Grounds can show good when shielding is inadequate, missing, or damaged. Shielding is responsible for keeping EMI out of a guitar's electronics, and that shielding has to continue throughout the signal path, and that includes the cable, external gear (pedals/effects), and amps. EMI (electro-magnetic interference) is what causes most hum issues, and usually starts (or gets in) where the shielding is weakest and voltage is lowest. In many guitars this is in the wiring cavity. Most of the Ibanez Iceman guitars fall into this category; no foil cavity shielding.

That said, if your Ibanez has not been worked on or modified or tampered with, the shielding in the wires inside the guitar should still be sufficient to keep normally encountered levels of EMI at bay. That leaves the rest of the signal chain, from the cable on through to the speakers. I would first make sure all of that is properly shielded at a quality level comparable to the guitar, and then if all that is fine, you may need a better shielding system. That usually entails installing special foil in the guitar cavities and maybe upgrading the wiring, depending on the model and pickups installed. For that you would take it to the shop. I would charge upwards of a hundred bucks for all that. Before you do anything like that, consider where you play the most: is it an area where there is a lot of EMI floating around? If so, can you practice/play somewhere else? Getting away from the source is better than spending money or firing up a soldering iron.

Sounds like you are checking continuity with your meter. All grounds and shields should be connected together, so first you have to identify all those points. You also should check all the solder joints from the solder to the metal the solder is on, with the meter on the lowest ohms setting, and you want to see all zeros, or at least 2 or 3 decimal places below 1 ohm, everywhere you check. btw it's the shield ring of the guitar's plug that is grounded, not the tip, which is signal.

Good luck :P
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