Help, I'm getting shocked by my guitar!

[wing]

So I recently acquired a small 1962 Gibson Skylark GA-5 amp, which has a 2-prong cord. After getting quite a buzz a few days ago while playing the guitar, I did research and learned that it would be best to convert the amp to 3-prong so that it would be safely grounded. I'm not concerned about amp resale value so much as safety, so I promptly did the conversion, according to this guide: http://www.unclespot.com/2to3prongconversion.html

Basically, it should be like this: cut the "death cap," green wire to chassis, white to transformer wire 1, black to fuse, fuse to switch, switch to transformer wire 2. And that's what I did.

But still, I was getting a little bit of an intermittent shock while playing guitar. It doesn't happen constantly, but it is most common when I play barre chords for whatever reason. The zap isn't as intense as before, but it was still kinda there, like licking a 9v battery or something.

So then I used a tester to make sure my outlet is wired correctly, and that passes. Then I tried a newer amp that I've never had issues with, and I was still getting an occasional fizzy feeling. And that's weird, because I've never had this problem before with that amp and guitar configuration.

So question: could there be some sort of major static discharge going on? It feels a little more intense than a typical static shock, though. Or could there be some issue with the wiring of the guitar? Can I use something like a DMM to test for proper grounding in an amp?

I can post some pictures of the rewiring soon. I hate this, though, because I want to record yet this is annoying and a little bit scary, should I receive a more major jolt...

[mrdibs]

Basically, it should be like this: cut the "death cap," green wire to chassis, white to transformer wire 1, black to fuse, fuse to switch, switch to transformer wire 2. And that's what I did.

Is the other side of the death cap still connected?

Also are you sure that your connection to the chassis is good? Can you measure 0 ohms from the ground pin of the plug to the chassis?

[wing]

Is the other side of the death cap still connected?

Nah, I soldered all of it off on both sides. But one thing to note, rather than attaching the green wire to one of the transformer pins as some people suggest, I soldered the green wire to the pin above the tube holder that is directly connected to the chassis--the same pin the death cap was previously connected to. But that should be fine, right, as it is still connected to the chassis?

Also are you sure that your connection to the chassis is good? Can you measure 0 ohms from the ground pin of the plug to the chassis?

Let's see... I measured all types of connections to the chassis, and I would get a reading of 0.1v. Is that an issue, or a negligible amount?

[wing]

Okay, here are some pics of my rewiring. Does this look right?





Note how I said the ground wire is attached to the pin of the tube holder that is attached directly to the chassis. When I check with a meter (black tester on ground pin, red tester on part of chassis), I get that reading of 0.1v.

Is this correct?

[Nick Sevilla]

Is the other side of the death cap still connected?

Nah, I soldered all of it off on both sides.
But one thing to note, rather than attaching the green wire to one of the transformer pins as some people suggest,
I soldered the green wire to the pin above the tube holder that is directly connected to the chassis--the same pin the death cap was previously connected to.
But that should be fine, right, as it is still connected to the chassis?

Also are you sure that your connection to the chassis is good? Can you measure 0 ohms from the ground pin of the plug to the chassis?

Let's see... I measured all types of connections to the chassis, and I would get a reading of 0.1v. Is that an issue, or a negligible amount?

Hi,

TAKE THIS TO A QUALIFIED REPAIR TECHNICIAN RIGHT NOW!!!

If you have to ask if your soldering looks ok, it probably is not...

You should be measuring OHMS, not VOLTAGE to ground, oh my...

We do not want to read your name in the obituaries section in a few days.

Cheers

[ashcat_lt]

I'll ditto that. If you have to ask, you should take it to a qualified tech.

But it's happening with another amp too... What's the floor made out of? Are you wearing shoes?

It's completely possible for the outlet to test fine - proper polarity, and ground is "close enough" to centered between the others - and still have the outlet ground with some potential difference to the concrete floor.

The fact that you're getting shocked means that your strings are properly connected to the chassis of the amp via the shield of the cable. Cutting this connection (usually a wire to somewhere under the bridge or on the trem claw) will keep you from being shocked when you touch the strings. It won't keep you from being shocked when you touch the cable, jack, or metal knobs, or the amp itself. It will also likely cause an increase in the overall noise level coming out of the guitar.

If you were to wire a suitable capacitor into this bridge ground connection, you might be able to attenuate the 60 HZ AC signal that's trying to flow through you, but it might mean that more 60 HZ noise gets into the guitar signal. Also (as above), wouldn't help when touching other metal parts on the guitar.

[Scodiddly]

Agreed - best to get somebody to look at it. They might also give you some good advice on the rest of the amp and what might need to be replaced.

But aside from that, given that it happens with a different amp as well, maybe your outlet ground isn't good? What are you standing on (shoes, barefoot, ???) when you feel electricity from the guitar? If you can feel it, can you take your meter and measure it?

[Jim Williams]

Okay, here are some pics of my rewiring. Does this look right?

I see dead people.

[wing]

Is it that hard to do? I feel like I'll pay a tech $100 for him to tell me, "looks fine."

Not saying that I am putting a minor price on my safety and my life. Of course it's better to be safe than sorry. But I followed every bit of instruction available for this basic conversion... And like I said, it was happening with my other newer amp that I've never had problems with, so I feel like it's probably not even the amp but something else...

[Nate Dort]

Is it that hard to do? I feel like I'll pay a tech $100 for him to tell me, "looks fine."

Not saying that I am putting a minor price on my safety and my life. Of course it's better to be safe than sorry. But I followed every bit of instruction available for this basic conversion... And like I said, it was happening with my other newer amp that I've never had problems with, so I feel like it's probably not even the amp but something else...

I had a similar problem once. The amp was plugged into an ungrounded outlet and I had a EH Deluxe Memory Man plugged into a different grounded outlet. Check the grounds at your AC outlets to make sure they're actually grounded to the bus bar at your breaker-box.

[roscoenyc]

We'll have 'em put "He did it his way" on your headstone:)