Help!!! My Mark IV keeps shocking me!! (shocking content)

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Rydock

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So when my amp is plugged in and turned on, every time I touch something metal on the amp (corner protectors, jacks, amp handle, etc) I either feel for a pulse or get a sharp shock. Can somebody tell me why it's doing this? I played around with the ground switch and it doesn't help at all.
 
Unplug and take to repair shop before you die screwing around with the amp.

Die, dead, *** laying in a smoking heap..... bad things....... Your life in exchange for saving a few bucks......
 
Does this happen everywhere you play or just in one outlet or using a certain power strip?

Get an outlet tester and test the outlet. I had the ground rail in a cheap power strip fail which lead me to find out that my amp had a short by me getting zapped pretty hard! I destroyed the power strip and repaired the amp.

This is something to take very seriously. People have died due to this problem.
 
You can get a decent plug tester at any hardware store. I use the Greenlee model: http://www.all-spec.com/products/GT-10.html I've had one for years and it has never let me down.

You should be able to get one just about anywhere.

Another great brand is Ideal.
Just about any plug tester should do for what you need. I make it a habit of testing every plug that I put my amps into.

If the plug is wired correctly, or if the amp does this in all plugs that you try, then you may have a faulty ground in your amp, and something may be touching the chassis that should not.

This is really, really dangerous! Don't play the amp until you get it figured out!
 
Monsta-Tone said:
Just about any plug tester should do for what you need. I make it a habit of testing every plug that I put my amps into.

I do too. I carry an outlet tester in my guitar case. Just this past weekend we played a BBQ and the home owner's father replaced an outlet as we set our equipment up. He is a contractor and I trust the guy completely but I still tested it with my outlet tester before pluggin into the outlet. He was happy to see that I tested it (it was fine).
 
Of course I'm going to send the amp into a tech to check it out. I never said anything about saving a few bucks. I know how serious this is, that's why I've unplugged my amp and didn't bother touching it again while posting this question. I just want to find out if this is a common problem with these old amps, and isolate it so that I know what I'm dealing with before sending it in for repair instead of blindly taking it to the tech.

I probably won't be able to do this until the weekend though, so I'll just give you guys some more info to help isolate the matter. I've noticed that the mark had this very strange hum coming out of it, and if I touch the metal knobs on my guitar, it sounds scratchy like the pots are dirty or something. I thought it was the guitars fault at first, so I tested the guitar through other means (i.e. a POD and a practice amp). I confirmed it wasn't the guitars fault for the noise. Next, I really doubt it could be my houses wiring, but I won't know for certain I purchase an outlet tester. I've never had this hum problem with my old roadster in the same outlets I've used for my mark. I even plugged my amp into two different sockets in a different room (this is when I received a shock for the first time). I used both wall outlet and power bar (it's a pretty new power bar from a reliable brand, and not a cheapie you get from the dollar store).

Going from these facts, it's likely that it's the amps fault, and that is a grounding problem. I must add that I think that the ground switch might be defective, as it doesn't respond at all when set in any of the three positions.

So if anybody can let me know if this sounds like a familiar problem (i.e. defective ground switch), please let me know what the possible problems are, so I can take it to the take and let him know exactly what I think is going on. I'm obviously not going to be to playing around with the amp or testing it further until I get this problem fixed.

Thanks guys
 
Is the ground switch in the center position? That's where I would start the troubleshooting. If yes, try it in another outlet. If the problem still persists, send the amp to a tech.
 
If you have a little experience, I would drain the caps. These amps seem to drain enough by playing through it and pulling the powere cord out while you keep strumming. Check with a meter. Take a look inside. I would check the standbye switch. Maybe a wire let loose and is touching the chasis. My guess is you got hit with AC not DC. DC would have been one hell of a shock. Good luck. I have my MK IV open now. Just replaced all of the filter caps and I am happy it came out clean from the topside of the board.
 
also, it you have a meter, check your wall socket to ensure you have a good ground. Often times, in older homes, people upgrade the outlets to 3 prong type recepts yet never actually connect the ground back to reference. Was an electrician for many years and saw alot of this.
 

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