Pedals are shocking me!

[austingreen]

Actually I think it's my amp or amps, here's the story:

While playing through a 2 amp stereo setup (via EHX 2880) and switching around the cables on my pedals, everything on, amps on standby, holding down Memory Man with one hand and removing a cable from it with the other I received a major shock. The plug has a metal casing. The lead was coming straight from an old Airline amp and I was touching the metal casing of the MM which still had a cable plugged into the 2880 which had an output plugged into the second amp.

Here's my setup:
Guitar into 11 pedals all powered by one One Spot, except Holy Grail, Memory Man, and EHX 2880 (looper) use they're own adapters. 2 outputs (L/R) from 2880 into 2 circa 50's tube amps (Gibson GA50, Airline). Gibson recently worked on and a 3 prong cable installed. Airline still has 2 prong cable.

I'm sure the outlets in my house are not grounded properly. I switched that particular cable to one with a plastic cover on the plug housing. But I have three "nice" cables that have this metal housing.

This has happened to me before and it was most likely with one of the two amps mentioned. The first time it was just the lead coming out of the amp laying on ground (not sure if amp was on or not, long time ago and different house) near a Holy Grail, power adapter plugged in but no other cables attached. So I accidentally laid my bare foot on top of cable and Holy Grail at the same time and received a nice shock.

What's the deal? Are the metal chassis of EHX pedals dangerous? Is it dangerous to play out of 2 amps at the same time if one or both is not grounded properly? Are vintage amps or any 2 pronged equipment normally dangerous in this scenario? Or (most likely) is it just the fact that the house is not up to current electrical code (house is 40 yrs old at least)??

Finally, what's the quickest and cheapest way to protect myself from this happening (other than not doing it)? And what would be the safest but not always most cost saving approach?

Sorry for the long story and thank you for any advice.

[The Scum]

What's the model # for the Airline amp?

Type it into Google, and see if you get a schematic.

Then look at the schematic and tell us: does this amp have a power transformer?

Do you own a volt meter?

Rough guess: no power transformer + miswired outlet = hot chassis.

[austingreen]

Airline Model #: 62-9015A
I'm not able to find a schematic online, there is an guitar amp book by Jack Darr that supposedly has it. Coincidentally there's an article about this amp in the current Vintage Guitar magazine. And there is one for sale on ebay.

I do own a volt meter, though am completely ignorant where to look and what to look for, barely know what a power transformer looks like. Sounds like I should take the amp to get looked at?

[farview]

Gibson recently worked on and a 3 prong cable installed. Airline still has 2 prong cable.

I'm sure the outlets in my house are not grounded properly.

I could be wrong, but I think this is your problem.

Are the metal chassis of EHX pedals dangerous?

No.

Is it dangerous to play out of 2 amps at the same time if one or both is not grounded properly?

Yes. it's actually dangerous to play out of one amp that isn't grounded properly any time you can come in contact with something that is.

Are vintage amps or any 2 pronged equipment normally dangerous in this scenario? Or (most likely) is it just the fact that the house is not up to current electrical code (house is 40 yrs old at least)??

Using 50 year old amps in a house with 40 year old wiring in a way that was never intended in the design of either amp is going to be a potential problem.

Finally, what's the quickest and cheapest way to protect myself from this happening (other than not doing it)? And what would be the safest but not always most cost saving approach?

Get the other amp moded with a three prong plug and make sure that the outlets you are plugging into are wired correctly.

[The Scum]

My copy of Pittman's book doesn't have a 62-9015a...a GDR9015a and G1M9015a, but no "62."

Is your amp like the one on Ebay?

That big black square thing on the back panel is a transformer. Does your amp have one thing like that, or two?

[ashcat_lt]

AC leakage.

Get the Airline grounded now.

[Snarl 12/8]

Get the other amp moded with a three prong plug and make sure that the outlets you are plugging into are wired correctly.

I'd make sure they were plugged into the same correctly wired outlet to avoid a ground differential.

[Scodiddly]

AC leakage.

Get the Airline grounded now.

Cheaper than a trip to the hospital!

[firesine]

I got bit the other day by an old Gates stereo limiter with a two prong plug. Plugged it in, went for the on/off switch and she got me good. I figured this was because the unit wasn't grounded (only two prongs).

As an experiment, I turned the unit off (with a pencil) and flipped the plug around so the prongs were in opposite sides of the socket. Turned the unit on with my finger and no shock at all.

So, can gear with two prong plugs still be grounded through one of them, as long as it's plugged in the right way? Or did I just get lucky the second time?

[Snarl 12/8]

I got bit the other day by an old Gates stereo limiter with a two prong plug. Plugged it in, went for the on/off switch and she got me good. I figured this was because the unit wasn't grounded (only two prongs).

As an experiment, I turned the unit off (with a pencil) and flipped the plug around so the prongs were in opposite sides of the socket. Turned the unit on with my finger and no shock at all.

So, can gear with two prong plugs still be grounded through one of them, as long as it's plugged in the right way? Or did I just get lucky the second time?

That's why on more modern 2 prong stuff one prong is slightly fatter (and hopefully longer) than the other. Then, the outlet has one slightly fatter slot so that it can only go in one way. If you trace that fat prong back to the chassis you'll usually find it bolted to it - ground. Also, look in your electrical junction box, all the grounds and the black wires from the romex are going to the exact same place. A big aluminum bar at the bottom. Basically, 3 prong is 2 grounds and a hot. Better to have 2 grounds than none. But one's enough, usually, if everything's set up correctly. I love AC. Thank you Mr. Tesla.

You're still way better off with 3 prongs on everything, since it reduces miswirings a lot, and it only takes one miswiring to killya.

[Knights Who Say Neve]

Get a 3-wire plug put on that airline amp now!

AFTER you do that, plug both amps and anything else with an AC cord into one outlet via a multistrip. Different outlets can have different "ground potentials", resulting in shock when you bridge one ground to another with your body.

But, get a 3 wire-plug on that amp first! It will add what's called, for good reasons, a "safety ground".

[The Scum]

All of you 3-wire pushers are assuming that the amp in question has a power transformer...in which case, the conversion is easy.

But there are amps from that era that were built without a transformer. Airline, Kay, Supro, etc among them. So that the real crux of the situation here. If it needs to have one added, it's not impossible, but not exactly a cheap part, and not something I'd trust a layman to do - even unplugged, there's power stored in the amp, and you'd be soldering the new component right in that part of the circuit.

Plenty of reading on the amp w/o power transfrmer subject all over the net:
http://www.google.com/search?q="hot+chassis"+guitar+amp

[Knights Who Say Neve]

"pushers"?

Anyway, a 120:120v isolation transformer is not an insanely expensive part (in my opinion) and if it is an AC amp you'd better get one added for safety's sake, expensive or no.

[Scodiddly]

I got bit the other day by an old Gates stereo limiter with a two prong plug. Plugged it in, went for the on/off switch and she got me good. I figured this was because the unit wasn't grounded (only two prongs).

As an experiment, I turned the unit off (with a pencil) and flipped the plug around so the prongs were in opposite sides of the socket. Turned the unit on with my finger and no shock at all.

So, can gear with two prong plugs still be grounded through one of them, as long as it's plugged in the right way? Or did I just get lucky the second time?

Back in the dangerous old days of ungrounded outlets, the amps usually had a polarity switch and what techs nowadays call the "death capacitor" to sort-of ground the chassis (at least as far as RF interference was concerned) to one prong or the other of the two-prong plug. Modern practice is to remove the death cap and ground the chassis only to the AC ground on a three-prong plug.

[Scodiddly]

...Oh yeah! I almost forgot, which would have been a bad thing. That you're getting a shock in one position of the plug means that you've either got a shorted death cap or a hot chassis.

Get it fixed!!!!!!