How Did I Just Get Shocked Turning my Amp On?!?

[Lowspeid]

I have a Victoria 20112. It’s an earlier model with just the on/off switch, no standby. I have it plugged into a good quality power strip, along with 2 other amps and my pedal board. I’ve been swapping speakers in and out of the Vic the last couple days so it’s been open and had the tubes pulled and re-installed several times to accommodate the speaker swaps. I had been swapping the lead back and forth a/b/cing my 3 amps, and turned the Vic off to play through my Marshall. When I went to turn the Vic back on I got a little “bite” from the toggle. I also noticed that after the last speaker swap it was hissing/humming loudly, even at idle.

Any INFORMED ideas as to why I got shocked, and what I might want to look for so I don’t get bit again?

 

[dankilling]

Sounds like it’s time for a trip to the amp tech. Getting bit and excess hum are definitely signs something isnt right.

 

[Lowspeid]

Sounds like it’s time for a trip to the amp tech. Getting bit and excess hum are definitely signs something isnt right.

I hope not. There isn’t an amp tech within 2 hours of me. I’m thinking it has to be something simple. I swapped speakers last night, and it was fine. Swapped it back this morning and something isn’t right.

 

[schmee]

Get one of those little testers and test the wall plug, maybe the neutral is swapped or something and you just happened to discover it?
It wasn't just static electricity?
Visual chack inside the AC wire routing to make sure a wire didnt get out of place, or the green ground broken off etc.

 

[Si G X]

I hope not. There isn’t an amp tech within 2 hours of me. I’m thinking it has to be something simple. I swapped speakers last night, and it was fine. Swapped it back this morning and something isn’t right.

Nope take it to get looked at, don't 'hope' when it comes to getting electrocuted.

 

[dan40]

My guess would be static electricity also. In a modern amp like yours, the chassis is grounded to earth through the power cord. It is possible that the outlets in your home are not wired properly which would defeat the safety ground in the power cord. An inexpensive outlet tester as Schmee mentioned would let you know if the outlet is properly grounded.

The hum/hiss you mentioned may be a bad tube. Do you have any spares that you could swap in?

 

[printer2]

I was asked to check out a laser machining center as the operators have been getting shocks. After a while of not getting anywhere I talked to the operator and asked exactly what they did before getting shocked. In the end I found it was static electricity from sliding off the chair before touching the enclosure (the center is surrounded so no laser radiation is visible to people). Not to say that is your problem but in colder weather inside air is dryer.

 

[Powdog]

I question your good quality power strip. It’s the weak link. Victoria amps are wired pretty meticulously, nothing passive that would go wrong by swapping tubes and speakers.

 

[Lowspeid]

Well, I kinda feel like an idiot. I opened the back panel and noticed right away that the V2 tube was barely in it’s socket. Somehow I misaligned it and was barely in there, with the metal pins almost touching the metal shield. I think I got a little jolt from the tube not being seated in the socket properly (metal tube shield connected to metal chassis connected to metal toggle switch). I pulled the 12AX7, reinstalled it making sure it was properly seated, and viola! No hum/hiss ( any more than normal anyways), and no shock.

Just to be 100% I checked the wall outlets with tester. They are fine. I will be purchasing an even better power strip though.

 

[Lynxtrap]

If safety ground is working as it should, you should not get a shock from the amp. If a tube shorted to chassis, it's a also bit strange that it didn't blow a fuse.

 

[JPKmusicman]

^ Agree. The safety ground path should be much lower impedance than your body. Maybe it wasn't enough current to trip the breaker, but possibly a GFCI breaker/receptacle would have tripped. I would double check the safety ground to chassis mechanical connection. Make sure it's tight and no corrosion.

 

[Lowspeid]

^ Agree. The safety ground path should be much lower impedance than your body. Maybe it wasn't enough current to trip the breaker, but possibly a GFCI breaker/receptacle would have tripped. I would double check the safety ground to chassis mechanical connection. Make sure it's tight and no corrosion.

Where would that be in a 5e3?

 

[JPKmusicman]

Where would that be in a 5e3?

Usually right where the 120 VAC cord enters the chassis. See picture (red arrow). Should be the green wire. Just make sure all power is off and capacitors are discharged before you touch anything in there.

 

[Lowspeid]

Usually right where the 120 VAC cord enters the chassis. See picture (red arrow). Should be the green wire.

Awesome! I’ll look it over!

 

[Lynxtrap]

Where would that be in a 5e3?

This question worries me a bit. In addition to JPKmusicman's advice, unplug the cord from the wall before doing anything else!
Make sure you know how to discharge caps! Try not to touch anything inside the chassis.

 

[King Fan]

Sorry to ask basic questions, but: Do you have a meter? When working inside an open chassis, can you drain the filter caps?

Even more than visual inspection, you really want to test electrical continuity of your amp's whole safety ground. Luckily, you can do this totally safely, amp buttoned up, unplugged, without draining the caps, if you have a meter. Rob tells us how: "Plug a guitar cable into an input jack and check that you have continuity (meter "beep") between the guitar cable's sleeve (the part that isn't the tip) and the amp's power cord ground prong."

 

[JPKmusicman]

This question worries me a bit. In addition to JPKmusicman's advice, unplug the cord from the wall before doing anything else!
Make sure you know how to discharge caps! Try not to touch anything inside the chassis.

I later edited my post and put those similar comments. It cannot be repeated enough.

 

[Lynxtrap]

I later edited my post and put those similar comments. It cannot be repeated enough.

I wanted to stress that turning the power off is not enough if the amp is plugged into the wall outlet, especially when poking around near the 120AC input.

 

[schmee]

First, as several folks have suggested, you really need to test your outlet with a tester -- they're cheap at any hardware store and handy around the house to help prevent shocks, serious appliance / amp / TV / computer damage, electrocution, and fires. A strikingly high percentage of US homes have bad ground or no ground at the outlets. And yeah, reversed neutral is pretty common too.

*That might just be the most likely -- and most dangerous -- reason you got shocked.* And though you might not need a tech, you might need a household electrician.

After that, it's worth asking is your chassis properly grounded? (Sorry to ask basic questions, but: Do you have a meter? When working inside an open chassis, can you drain the filter caps?)



To inspect visually, if your Vicky is like this, look at the green household lead here.

View attachment 1060363

But even more than visual inspection, and IF your outlet is properly grounded, you really want to test electrical continuity of your amp's whole safety ground. Rob tells us how: "Plug a guitar cable into an input jack and check that you have continuity (meter "beep") between the guitar cable's sleeve (the part that isn't the tip) and the amp's power cord ground prong." Note you can do this totally safely, amp buttoned up, unplugged.

​

FYI: He already said he tried the socket tester. Post 9
Good thought on the ground test!

 

[King Fan]

FYI: He already said he tried the socket tester. Post 9
Good thought on the ground test!

Thanks, my friend. My bad. Edited out that part of my post, now wiping egg off face...