Shock from My amp!

[jajabinker]

Amp : Fender JazzMaster Ultralight (notorious)

After keeping the amp on for a few minutes i get a shock! the earthing fails. If i connect an external earthing wire to the chasis, the shock stops.

Upon opening and inspecting the amp, I see that no wires are lose. The earthing wire is screwed tight to the chasis.

The problem keeps repeating on every turn on and its hard to play ballads with all this electricity.

Can anyone point me in a helpful direction.

MY INVESTIGATION:

I see a bunch of safety X Y capacitors. Are the failing and causing the shock? Can anyone help try and identify them to help me replace.



Regards,

Jonathan

PS I hope im descriptive enough.

[52 Bill]

Welcome to the place.

The very first thing that I would test would be the plug/cord wire. If grounding the chassis with an external wire stops the shock, then there must be problem with the ground connection of the ac cord or the amp socket.

[jajabinker]

Thank you Bill.

I checked the power chord terminals with a multimter. All are okay with no leaks. Other appliances work fine

[Jazz P Bass]

This amp utilizes a Switch Mode Power Supply.

Be very careful in there!

As there is no known schematic available for the power supply, the answer to your question "I see a bunch of safety X Y capacitors. Are the failing and causing the shock?" depends on how they are wired in the circuit.
If one end is attached to the chassis ground, then yes, there is a shock potential if they are bad.
I see that the ceramic caps are dual X1/Y2 rated.
For Line to Line use or for Line to ground use.
X capacitors are used Line to Line.
If they fail, they do so in a shorted manner.
Then the mains fuse blows.

Y capacitors are used Line To Ground.
They fail open.

[jajabinker]

Thank you Bill.
I checked the power chord and the plug for leakage using a multimeter. It works fine.

[Enzo]

I agree with the above suggestion to check the power cord first. The internal ground connections in the cord could be intermittent. Is ther an IEC connector - ie the power cord comes off? That connector could be loose, cracked, broken solder.

[jajabinker]

Thank you bill. Great to be here. I’ve checked the power chord with a multimeter. There are no leakages.

[jajabinker]

All the capacitors are connected to the chassis ground via the circuit board. They are 2 types, 680 pf and 1500 pf safety caps. X1 400V and y2 250V.

[jajabinker]

I’ve checked the connector as well. No leakage. There’s no solder on it, uses those clip like thingies that fit real snug. Idk what they’re called.

[olddawg]

I agree as well. Do a continuity test between the chassis ground and the earth ground
at the plug end. Also be aware that the outlet you are using may be floating even if it has a modern receptacle. I see this all of the time in older buildings.

[Jazz P Bass]

Which does beg the question "Why is the OP getting a shock?"

How is a voltage potential being developed between the amp & the guitar.

Even ungrounded, there should not be any voltage on the chassis.

[dstrat]

maybe wall plug wired backwards , hot neutral?
other wise idk

[Leo_Gnardo]

Which does beg the question "Why is the OP getting a shock?"

How is a voltage potential being developed between the amp & the guitar.

Even ungrounded, there should not be any voltage on the chassis.

Maybe standing barefoot or in conductive/wet footwear on a concrete floor. Or outdoors on a lawn or wet deck. Those can get you a tingle or more from hands thru the feet. It's happened to me, feels weird. And it's worrisome wondering if the shock is gonna get worse. Good question!

[Enzo]

Yeah, I don't recall him saying he got a shock touching the amp, he was just "getting a shock." SO in my mind that means off the mic or the floor or other gear, or whatever.

[jajabinker]

I get a shock touching the amp or the guitar! Ive used a tester it goes live.