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previous: john hermsen Hi,I was strumming ... -- 7/17/2000 11:50 PM

Re: Safety info/warning

7/19/2000 11:23 AM
SteveG	Re: Safety info/warning I've had several shocks since I started working on guitar amps. I always find out exactly why it happened, (carelessness, almost without exception) and endevour not to let it happen again. A few weeks ago, though, something happened that bothered me. I got a shock when I touched the metal can of a smoothing cap that was definitely connected to ground (other hand not touching anything). I uttered my favorite expletive, brushed myself off, and measured the voltage on the cap body. Result - 0v. Went to bed. Next day, I noticed that a pre-amp valve was split in half. What happened, exactly? Can the failure of a pre-amp valve cause the chassis to go live, even though it's connected to ground? If so, how? Had I been playing a guitar with the strings grounded, would I have experienced a similar shock? The amp worked fine again BTW, once the faulty valve was replaced. This has been bothering me ever since, and I'd like to hear any theories or similar experiences, so that I can avoid this happening again in future. Thanks Steve

7/19/2000 11:23 AM

SteveG

Re: Safety info/warning

I've had several shocks since I started working on guitar amps. I always find out exactly why it happened, (carelessness, almost without exception) and endevour not to let it happen again.

A few weeks ago, though, something happened that bothered me. I got a shock when I touched the metal can of a smoothing cap that was *definitely* connected to ground (other hand not touching anything). I uttered my favorite expletive, brushed myself off, and measured the voltage on the cap body. Result - 0v. Went to bed. Next day, I noticed that a pre-amp valve was split in half.

What happened, exactly? Can the failure of a pre-amp valve cause the chassis to go live, even though it's connected to ground? If so, how? Had I been playing a guitar with the strings grounded, would I have experienced a similar shock? The amp worked fine again BTW, once the faulty valve was replaced.

This has been bothering me ever since, and I'd like to hear any theories or similar experiences, so that I can avoid this happening again in future.

Thanks

Steve