ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: 1 [2]  All   Go Down

Author Topic: Grounding info that could save your life.  (Read 7049 times)

John Roberts {JR}

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 16394
  • Hickory, Mississippi, USA
    • Resotune
Re: Grounding info that could save your life.
« Reply #10 on: July 02, 2014, 10:22:58 am »

I had several Fender amps like this back in the 60's and 70's when I was a long-haired hippie child playing in a band. You would flip the switch back and forth and feel for the position of least shock (no kidding). IIRC my Kustom 100 also had this same sort of switch on the back. NOTHING was grounded in our backline or PA back then and we were always getting some kind of shock. But that was accepted as normal and part of playing "electric" instruments.

OT but really cool were the Red & Blue jeweled power lights on the front of old Kustom amps. They were visually hard to focus on which made them very easy to recognize from the back of the club.

You were supposed to switch it for least audible hum, it wasn't supposed to give you a (dangerous) shock in either position. I am a little surprised that UL blessed the concept. They surely specified the type caps used for that task. 

This has been discussed before but you can cap couple the ground inside the guitar to adequately reduce hum while increasing human safety.

JR
Logged
Don't tune your drums half-ass. Listen to what a properly "cleared" drum sounds like.   http://circularscience.com/

Mike Sokol

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3356
  • Lead instructor for the No~Shock~Zone
    • No~Shock~Zone Electrical Safety
Re: Grounding info that could save your life.
« Reply #11 on: July 02, 2014, 12:39:27 pm »

You were supposed to switch it for least audible hum, it wasn't supposed to give you a (dangerous) shock in either position.

Yeah, but I can remember getting shocked a bunch of times. Of course, if the cap shorts out then it's a killer when switched to the (random) line side.

Mike
« Last Edit: July 02, 2014, 12:52:27 pm by Mike Sokol »
Logged
Mike Sokol
mike@noshockzone.org
www.NoShockZone.org

Jeff Bankston

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2269
Re: Grounding info that could save your life.
« Reply #12 on: July 02, 2014, 04:19:12 pm »

i'm glad we are having this discussion. i will find out if anyone i know has an old 2 prong cord guitar amp and have them read this. what about 2 prong transistor guitar amps from the late 60's-up ?
Logged

John Roberts {JR}

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 16394
  • Hickory, Mississippi, USA
    • Resotune
Re: Grounding info that could save your life.
« Reply #13 on: July 02, 2014, 05:44:53 pm »

i'm glad we are having this discussion. i will find out if anyone i know has an old 2 prong cord guitar amp and have them read this. what about 2 prong transistor guitar amps from the late 60's-up ?

Any UL approved consumer electronic product of recent vintage with 2 wire line cord will have double insulated power transformers and no shock hazard... This is mainly very OLD guitar amps.

JR
Logged
Don't tune your drums half-ass. Listen to what a properly "cleared" drum sounds like.   http://circularscience.com/

Mike Sokol

  • Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3356
  • Lead instructor for the No~Shock~Zone
    • No~Shock~Zone Electrical Safety
Re: Grounding info that could save your life.
« Reply #14 on: July 02, 2014, 05:54:29 pm »

Any UL approved consumer electronic product of recent vintage with 2 wire line cord will have double insulated power transformers and no shock hazard... This is mainly very OLD guitar amps.

JR

Late 60's guitar amps are suspect, especially if they've been ridden hard and put away wet. JR, I have a pretty simple test method for testing potential line-to-chassis leakage on old amps. Should we compare notes before I loose this on the masses?
Logged
Mike Sokol
mike@noshockzone.org
www.NoShockZone.org

John Roberts {JR}

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 16394
  • Hickory, Mississippi, USA
    • Resotune
Re: Grounding info that could save your life.
« Reply #15 on: July 02, 2014, 06:14:12 pm »

Late 60's guitar amps are suspect, especially if they've been ridden hard and put away wet. JR, I have a pretty simple test method for testing potential line-to-chassis leakage on old amps. Should we compare notes before I loose this on the masses?

I trust your common sense ....  carry on.

My advice is to remove any such caps and switches and permanently hard wire in a grounded line cord.

End of story...

JR
Logged
Don't tune your drums half-ass. Listen to what a properly "cleared" drum sounds like.   http://circularscience.com/

ProSoundWeb Community

Re: Grounding info that could save your life.
« Reply #15 on: July 02, 2014, 06:14:12 pm »


Pages: 1 [2]  All   Go Up
 



Page created in 0.06 seconds with 23 queries.