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Ground loop after replacing battery snap?


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The plastic battery snap on my bass guitar broke apart, so I figured I'd try to replace it myself. The original was connected to a little 2.5mm TRS plug, so I took this out and soldered on a replacement battery snap. Now I seem to have a really bad ground loop, making itself known as a rather loud hum that disappears when I touch the relevant parts of the instrument. Does it seem likely that the ground loop was caused by:

1. Poor soldering (haven't done any since school)
2. Inadequate part (ie the replacement battery snap) or
3. Inadequate shielding round the base of the TRS plug

Thanks in advance.

S.P.

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I've obtained a replacement battery snap from Aria UK and installed it, but the ground loop is still there. So I guess it's either (a) an unrelated fault which I just hadn't noticed before, or (B) something that happened while I was poking around in the instrument's internals.

I'm now trying to track down the source of the ground loop. One thing I have noticed, which may be relevant, is that the noise disappears when I bridge from the plug on the guitar lead to the lowest string, but it doesn't disappear when I bridge to the highest string. The Aria Sinsonido has a stereo microphone in a tube in the bridge, so perhaps the problem is with the microphone under the E and A strings (or its connections).

Any thoughts, or do you think I should make another call to Aria UK?

S.P.

Edited by stylonpilson
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[quote name='stylonpilson' post='253903' date='Aug 3 2008, 08:21 PM']The plastic battery snap on my bass guitar broke apart, so I figured I'd try to replace it myself. The original was connected to a little 2.5mm TRS plug, so I took this out and soldered on a replacement battery snap. Now I seem to have a really bad ground loop, making itself known as a rather loud hum that disappears when I touch the relevant parts of the instrument. Does it seem likely that the ground loop was caused by:

1. Poor soldering (haven't done any since school)
2. Inadequate part (ie the replacement battery snap) or
3. Inadequate shielding round the base of the TRS plug

Thanks in advance.

S.P.[/quote]

Assuming it wasn't there before. I would check very carefully that you haven't dislodged any wires or troubled an existing dry joint or bad connections. Lifting the board out and use a bright light - look carefully for any dull or broken solder connections.

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  • 4 months later...

I've solved the problem. I replaced all the dimmer switches in the house with standard on/off light switches.

The first clue was when I noticed that my other basses were developing ground loops too. And all my amps. And it didn't make a difference which wall socket I plugged them into. I thought that this was a bit fishy.

S.P.

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  • 2 weeks later...

[quote name='Stylon Pilson' post='352879' date='Dec 12 2008, 04:34 PM']I've solved the problem. I replaced all the dimmer switches in the house with standard on/off light switches.

The first clue was when I noticed that my other basses were developing ground loops too. And all my amps. And it didn't make a difference which wall socket I plugged them into. I thought that this was a bit fishy.

S.P.[/quote]

What you were describing was not a ground loop hum, this only occurs if you chain multiple mains powered units whose earth paths may be at varying potentials.

What you had was inductive hum and I would suspect that you broke a screening link to the earth pathway when replacing the battery clip.

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[quote name='Stylon Pilson' post='352879' date='Dec 12 2008, 04:34 PM']I've solved the problem. I replaced all the dimmer switches in the house with standard on/off light switches.

The first clue was when I noticed that my other basses were developing ground loops too. And all my amps. And it didn't make a difference which wall socket I plugged them into. I thought that this was a bit fishy.

S.P.[/quote]

1. no hum
2. replace battery connector
3. hum
4. replace light switches
5. no hum again.

Logic dictates that you did not fix the actual fault. If you use the bass on stage where there's loads of stray electrical noise you might be disappointed. Just saying :)

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[quote name='thepurpleblob' post='360360' date='Dec 21 2008, 05:51 PM']1. no hum
2. replace battery connector
3. hum
4. replace light switches
5. no hum again.

Logic dictates that you did not fix the actual fault. If you use the bass on stage where there's loads of stray electrical noise you might be disappointed. Just saying :)[/quote]

=1 to that.

All you have done is remove the source of the noise, not fix what ever is broken that was protecting the basses electrics from the noise.

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