Shocked when touching attenuator, already ruled out the outlets. What’s next?

Steppin' Wolfe

Silver Supporting Member
Messages
5,056
I’m suspecting its the amp or attenuator; both speaker cables are thick and high quality, and haven’t given me any issues when I ran the system with one of my other marshalls after this happened - and prior to this incident I’ve had no issues with any part of my rig. The attenuator itself is relatively new and has only been used about a dozen or so times.

If the grounding was lifting on the speaker output Jack, which apparently is a known issue with the Marshall I was using when I got zapped would it result in the shock I got when touching the attenuator?
Some engineer in the 1940’s made this statement...”Anything that can go wrong will go wrong.” Imho, in this situation, it would be a safer approach NOT to accept that those cables need to carefully inspected. They are also the simplest thing to check out and repair if needed.
 

barcslay

Member
Messages
10
plug everything back in and start checking continuity to ground.
if your amp has a ground plug (hopefully not removed) and the speaker cable is intact the casing of the attenuator should be grounded too.
Are you lifting ground anywhere to kill noise? Done wrong could be dangerous as well
yeah, I’m using the standard 3 prong plug that came with the amp, no modifications and no ground lifting
 

barcslay

Member
Messages
10
With a $2 ground plug adapter from Ace.
OP-
Were you barefoot on concrete floor when this happened OR was it a cold dry day and you were on carpet when you touched it?
no, I was wearing my normal soled shoes. But I was on carpet - I live in the PNW so it’s around 50 degrees and relatively dry this week
 

Dr.Twang!

Wrangler, twangler, participle dangler
Gold Supporting Member
Messages
908
Err, that would disable an essential safety system.
If that’s ‘safe’, what’s ‘dangerous’?
Oops. Didn’t read carefully what was being described! Short attention span today. Sorry.
OP- got a multimeter??
 

J M Fahey

Member
Messages
2,429
An OT *is* an inductor, conceptually not different from a car ignition coil or a TV flyback.

No big deal if a speaker load is connected because it will absorb amp output energy but if disconnected high flyback voltage peaks appear.

High enough to shock you at the speaker side and thousands of volts at the tube plate side, enough to perforate OT insulation shorting it, arcing sockets or inside tubes, a mess.

That´s why it´s a no no to use tube amps unloaded.
 

Dr.Twang!

Wrangler, twangler, participle dangler
Gold Supporting Member
Messages
908
Are you still getting shocked by touching MASS? Was it a one time bite, like static, or was it continuous.....every time that you touched it? Did it shock you even after contact was finally made amp>attenuation>speaker load?
Put your meter on AC volts and check for potential between barrel of cable plug and amp chassis. DC too.
 

barcslay

Member
Messages
10
Are you still getting shocked by touching MASS? Was it a one time bite, like static, or was it continuous.....every time that you touched it? Did it shock you even after contact was finally made amp>attenuation>speaker load?
Put your meter on AC volts and check for potential between barrel of cable plug and amp chassis. DC too.
I will do that.

Essentially what happened: no sound from amp, went to hit the “bypass” switch on my Weber to see if maybe it was an attenuator thing, got bit on the hand touching the switch, and hand touching the strings, turned amp off immediately and thanked god. Later I turned the amp back on and could hear a very tiny bit of the amp, so I rolled the master volume left and right a few times and it kicked in just fine, no more shocks or anything. Like an idiot as I know I shouldn’t have done this, I did a quick slap to the bypass switch and Weber housing to see if I’d get bit again, but didn’t get any zap that time once my sound was coming through.
 




Trending Topics

Top