A Power surge from badly grounded amp killed my stompbox

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A Power surge from badly grounded amp killed my stompbox

Postby Mrutg » 19 Nov 2014, 23:45

A Power surge from badly grounded amplifier killed my DIY stompbox (a fuzz pedal), which worked before on other amplifiers.
I just moved to a place where not all electricity sockets are grounded and i didn't thought this might be such a big issue.
Factory made EHX pedals don't explode when exposed to this situation. Is there an easy way to protect a circuit against such
situation in the future?

The FX went down after connecting to amp and there was an electrical spark seen going from the enclousure of the effect to the ground (floor).
After checking the amps enclousure phase indicator blinked red on the amps metal parts and the guitar.
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Re: A Power surge from badly grounded amp killed my stompbox

Postby R.G. » 20 Nov 2014, 03:13

I'm sorry for your misfortune. A spark from the pedal enclosure to the floor indicates that there was significant voltage between the "signal ground" on the pedal enclosure, and the floor, which presumably was a real, true, down-to-the-dirt ground.

One thing that's good about this is that it killed the pedal and not YOU.

The thing to do to prevent similar situations is something I advised every guitarist to do in one of my articles on electrical power for amp: go to a hardware or appliances store and find a plug-in electrical-socket tester. These devices plug into a socket and tell you with LED lights whether the socket is wired correctly. If it's not, you need to make a responsible decision about whether it's worth your LIFE to play your amp in that location. And I'm not exaggerating the seriousness. Guitarists have been killed by live "signal ground" carried to their guitars.

There is a way to insulate yourself from such situations, but you probably won't like it. Go buy an isolation transformer with sufficient power ("VA" or watts) capability to run your entire AC power setup, plug that into the questionable outlet, and run your gear ONLY from that. Such devices are heavy - probably 10-20lb/5-10kg, and expensive, maybe US$30-75 for a suitable one. But this is much cheaper and faster than a funeral.

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Re: A Power surge from badly grounded amp killed my stompbox

Postby Mrutg » 10 Dec 2014, 01:01

Thank you for your reply.
The sockets have been grounded and there is no more problem.

I still don't know why the surge killed my DIY and spared EHX factory made one ;)
If someone is curious it was DBA Harmonic transformer clone. After changing the electrolytic cap it started giving sounds again but the sound is ... different. I
guess some transistors were also damaged. lol
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Re: A Power surge from badly grounded amp killed my stompbox

Postby DrNomis » 10 Dec 2014, 01:14

If you haven't done so already, I'd suggest getting a competent and licensed electrician to give all the power circuits in your house a good check-out to make sure that it is all safe and up to standard, sure, it might cost you a bit of money but a human life is priceless, get your amps checked out too while you're at it...... :thumbsup
Genius is not all about 99% perspiration, and 1% inspiration - sometimes the solution is staring you right in the face.-Frequencycentral.
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