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Post subject: Three-prong conversion?
Posted: Thu Aug 12, 2010 8:03 pm
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Hello folks,

I recently inherited a late '60s Fender Bassman head with a rather nice cabinet, in excellent cosmetic condition. It also functions perfectly, except at random times it will give me a minor shock, particularly when I touch the metal switches on the rear of the head, and when I touch another piece of electrical equipment in the room. Obviously that could mean something much more dangerous, so I'm here to ask for some help. The AC cord is currently two-pronged, which I figured could be bad. Will converting the cord to a three-pronged cord eliminate the electrical shock? I'm really uncomfortable using the amplifier when it continues to randomly shock me. I've also heard frantic warnings about a "death cap;" does this need to be replaced?

On another note, anyone know a good amp tech in the Hartford, CT area?

Thanks in advance!

-Jake


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Posted: Thu Aug 12, 2010 8:22 pm
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Sounds like you may have a leaky cap or bad grounding point somewhere in the amp. Prolly best to try and find a tech to check the amp over and put in a three prong cord. I would be very hesitant to use te amp as is. If you plug in a guitar, high voltage (like 400+ VDC) can go back into the guitar and the player.

Good luck with th amp!


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Posted: Thu Aug 12, 2010 10:25 pm
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BMW2002Ti wrote:
Sounds like you may have a leaky cap or bad grounding point somewhere in the amp. Prolly best to try and find a tech to check the amp over and put in a three prong cord. I would be very hesitant to use te amp as is. If you plug in a guitar, high voltage (like 400+ VDC) can go back into the guitar and the player.

Good luck with th amp!


+1

The power cable should be replaced with a full-grounded-and-insulated 3-conductor type, miminum size AWG16. Likewise, the "death cap" should be removed.

Stay safe, stay alive.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Posted: Fri Aug 13, 2010 2:26 am
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You just need a 3 wires grouded AC plug. This is why you have electrical shock.And removing the cap like write Retroverbial.

IMO, nothing wrong with the amp


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Posted: Fri Aug 13, 2010 4:08 am
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Not sure I'd say that there is absolutely nothing wrong with an amp that shocks you, that only has two-prong outlet plug. Depends on where the OP is getting shocked. Ground wire (third wire) should really only carry voltage when there is a short to chassis, as I take it. Wouldn't an amp shorted to chassis, for whatever reason, run a risk of other failures?


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Posted: Fri Aug 13, 2010 5:28 am
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BMW2002Ti wrote:
Not sure I'd say that there is absolutely nothing wrong with an amp that shocks you, that only has two-prong outlet plug. Depends on where the OP is getting shocked. Ground wire (third wire) should really only carry voltage when there is a short to chassis, as I take it. Wouldn't an amp shorted to chassis, for whatever reason, run a risk of other failures?


All the amps when I was a kid were two prong. Nothing like getting bit in the lip with 120 volts to make you be more careful. Fender had a polarity switch. Still a very dangerous option. The problem was not all outlets were properly wired. Some still aren't. Property owners who know nothing about electricity or even care replace outlets. You should always bring a tester to be sure.

I would get one of these for the bare minimum.
http://www.amazon.com/50542-Receptacle- ... pd_cp_hi_1

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Posted: Fri Aug 13, 2010 6:06 am
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Likewise,I grew up with 2 prong plugs on amps,and it was a tricky situation when playing with other guys who were plugged into different outlets because of polarity,nothing like seeing the blue spark jump to another guy's mouth from the mic,it's funny when it doesn't happen to you,shouldn't be though,...nowadays we take it for granted that everything is wired right but like Supro said,it might not be,it only takes a minute to check it with one of the testers.
I remove the "death cap" also,but keep them in a bag...I just cut the lead that's soldered to the chassis.


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Posted: Fri Aug 13, 2010 6:44 am
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Darn right about outlets. Just because it has three holes, don't mean that the ground is actually connected to anything. Ground fault indicators are nice to have, too.


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Posted: Fri Aug 13, 2010 10:45 am
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63supro wrote:
I would get one of these for the bare minimum.
http://www.amazon.com/50542-Receptacle- ... pd_cp_hi_1


I carry one in my gear bag to every gig or jam -- along with a cheapie DVM.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Posted: Fri Aug 13, 2010 11:52 pm
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I tend to agree with BMW, about having the amp checked out. Had a young guy bring in a '65 Band Master with the same condition that you describe. It had the original filters and all but one of the original tubes. One of the RCA power tubes had been replaced with a GE, they were still within 6ma of each other ! At any rate, after a cap job, 3-prong power cable, normal maintenance, and a requested total tube R&R the amp was fine. And after my usual follow-up call, he was very happy with the amp. Actually did that job for parts cost, the RCA black plate and a couple of good used tubes from his dad. Art

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