The Watering Hole

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Per Spud's post, in a previous topic, tis time to address a serious issue - electrical safety.

Electricity, especially the stuff that exists in tube amps is DEADLY.  So, PLEASE be careful if you're cracking cases on these things and having a look see inside.

My electronics instructors, when I was in college, used this saying:

WHEN YOU'RE WORKING ON SOMETHING ELECTRONIC ALWAYS KEEP ONE HAND IN YOUR POCKET!

Sounds a bit "wierd" but, electricity can only kill you if it crosses the chest and hits the heart.   This can only occur if you've got two hands in the chassis.  To get into this state of affairs, one must have a hand placed on the chassis ground (which is the metal chassis) and the other hand on a "hot" lead somewhere within the chassis.  On most tube amps, especially those wired point-to-point, this is EXTREMELY easy to do.   Keep one hand in your pocket and you'll end up with some sore fingers, and a lesson learned, but not dead.

Remember, too, that capacitors, in some of the older amps, also maintain charges (most newer designs have "bleeder resistors" to bleed off the charges).   ALWAYS use caution around the caps in the amp - especially those in the high voltage power supply (they're usually the largest ones in the amps).   Bypass them (short) with a resistor (recommended) to bleed off any charges.   A resistor value of 1K, or higher, is recommended.  Direct shorts (wire) will cause fireworks and, in some cases, can/will damage caps and/or burn fingers.  The higher resistance value resistor allows the same thing to occur without all the fire/sparks.   USE ALLIGATOR CLIPS AND ONE HAND TO DO THIS WORK, TOO!  Keep yourself safe.  

That's all I really have to say about the issue. If you're not paying attention you can end up dead and, trust me, that's not a very fun place to be, from what I hear from those voices in my head.  I don't mean to make light of the issue, but caution does need to be exercised every time an amp is opened up!

Enjoy... if you're practicing safe modding, it'll be fun and productive.

Dar

This is why I don't do anything inside my amps, except for the biasing the HRD. Not that I could not learn, but I would rather take a class, or learn from someone first hand than find out the hard way and wind up dead.
Hey Dar....you'll like this.  ;D

Back in the middle 70's when we were young & dumb, I had this friend that had a Silver face Fender Twin with the ground switch.

This guy was wound up tighter'n Dick's hat band.  ;D

He played a strat and when we'd jam, he'd hold his strings & neck with one hand, then tap the vocal mic with the other.
He'd get no shock, smile, take a puff off his cigarette and then maybe grab a drink from his glass.

So while he's puffing on his cig, I'd have my bass player get his attention, then I'd switch the ground!  :o
We'd start up a song and he'd mosey on up to the vocal mic and......POW

Then you'd set your guitar down and start running like hell cause this guy was pissed!  ;D

Man, you could see a BIG BLUE spark light up between his lips and the mic!  ;D

Ahhhh....the good old days.

Randy
yep, "it's all fun til someone gets electrocuted!"

Then it's REALLY fun!   :)

I know a guy who did that once and it shocked him so badly (and he had been drinking) that he pee'd himself ON STAGE in front of about 300 people!  He said he wasn't even embarrassed because everyone thought it was so funny he just kept singing!  

Course, if that was Rudy's band, they'd have been trying to take the mic and poke him in the crotch afterwards!   :D :D :D