Welcome, Guest. Please login or register.

September 29, 2020, 03:56:43 PM

Login with username, password and session length

Recent Posts


Author Topic: rackmount preamp zapped me  (Read 3694 times)


  • Guest
rackmount preamp zapped me
« on: October 04, 2006, 11:37:23 AM »
So there I was playing late at night, and when I went to adjust a setting on my amp, I felt that weird twinge/tickle on my hand as it brushed against the metal face plate.

Having felt that sensation before, and knowing that it's not a good thing, I put the guitar down and grabbed my digital meter. Started checking all the gear that was plugged into the outlet strip, one by one. Eventually got down to just one component left as the source of the zap. My ART LT pre-amp. It's rackmount, and has a fully metal case and front. Touched the meter probe, and sure enough: 120 volts at any of the metal parts.

So now I'm going to open 'er up, discharge the caps, and do all the usual precautions. But is there anything that I should be looking for? The pre-amp was working fine (and in fact, still worked fine when it was shorting out), so it's not like I saw a puff of smoke coming out of it or anything. No mods that I know of either. Any suggestions? I love this thing and the sound it makes (has great clean and distortion settings), but I'm not willing to die for it.  :trouble


  • Master
  • ***
  • Posts: 94
  • Chip Points: 2
    • View Profile
Re: rackmount preamp zapped me
« Reply #1 on: October 04, 2006, 12:26:35 PM »
Well, it's usually some weird ground issue that causes equipment to shock me... try plugging it into a different outlet, that usually works for me (although I'm not exactly sure why). I suppose it could be some sort of loop with the poweramp, guitar... etc. Are the preamp and poweramp grounded (three prong plug) and/or have polarity switches?


  • Guest
Re: rackmount preamp zapped me
« Reply #2 on: October 04, 2006, 12:42:07 PM »
oh yeah, everything's got a 3-prong plug, and the outlet itself tests ok with the safety tester.

It's definitely a prob with the pre-amp, though, since I unplugged all the other stuff and disconnected them from the pre-amp. Even switched off, the pre-amp has 120v going through the chassis.  :-X


  • SSGuitar Admin
  • Legendary
  • ******
  • Posts: 3319
  • Chip Points: 991
  • SSG Creator
    • View Profile
    • thatraymond.com
Re: rackmount preamp zapped me
« Reply #3 on: October 04, 2006, 01:07:10 PM »
Must be a poor ground inside the chassis and/or one of the two power leads got stripped and is touching somewhere.
Life is what you make it.
Still rockin' the Dean Markley K-20X