Why is this reverb cable shocking me?

[Randall]

Ampeg V2 finished up, but when I touch the input reverb cable I get a shock. Then when I put my meter on it, there is no voltage. I figure that C209 is bad, so I replace it. I test the amp, everything looks great, so I power down by pulling the AC plug to drain the filter caps, and as I go to put the reverb cable on the tank, Snap!

Is that .47 cap charging up and biting me? Is this normal?

https://ampeg.com/support/files/Sche...20Version).pdf

[Dave H]

Is that .47 cap charging up and biting me? Is this normal?

The right terminal of C209 is open circuit when not connected to the tank. I guess it's charging up through you when you touch it. When the meter is connected the cap charges up through the meter resistance and will give no voltage reading when fully charged.

[Leo_Gnardo]

Is that .47 cap charging up and biting me? Is this normal?

Yes. Normal AND annoying. You can add a bleeder resistor maybe 10K ohm between ground and the end of the cap that goes to the reverb tank. That will dissipate the charge and prevent annoying shocks in the future. Same problem in lots of 60's and early 70's Ampegs where the tank is driven right off the plate of a tube with a capacitor to block high DC voltage and just allow signal through. Why Ampeg couldn't apply a resistor there for safety, well ya gotta save money ya know!

[Randall]

Stupid thing must have bitten me 5 times since it's been here. With the cable connected to the tank, does it get bled to ground thru the transducer? Would that not bother anyrhing?

[nosaj]

Stupid thing must have bitten me 5 times since it's been here. With the cable connected to the tank, does it get bled to ground thru the transducer? Would that not bother anyrhing?

Did you record it? Reminds me of the Gerald Weber shock

nosaj

[Leo_Gnardo]

With the cable connected to the tank, does it get bled to ground thru the transducer?

Yes, exactly that. AND that's why I don't plug an energized Ampeg reverb drive cable into a tank, worried that the sudden discharge might cause the microscopic wire in the drive transducer to fuse, that would be a big whoops!

nosaj's request for a recording of you getting bit by the shock, I can just imagine: "OW! ... @#$! mamma mia! caramba! um Gottes willen! ow ow ow!" Well that's pretty much what I do, practice a few languages including blue.

[Randall]

"nosaj's request for a recording of you getting bit by the shock, I can just imagine: "OW! .."

Um, I'm Italian, so a video of me getting bit probably wouldn't be fit for a family audience, if you know what i mean.

[DrGonz78]

I had worked on a V4 that was missing the reverb tank. Those reverb cables were just floating around in the chassis. While researching the amp I read about how those plugs can have voltage on them, especially at turn or something. Shrink wrapped and secured those suckers for sure.

[Dave H]

Stupid thing must have bitten me 5 times since it's been here.

Once is unlucky, twice is careless but five times?

[Randall]

"Once is unlucky, twice is careless but five times? "

I had them tied off to the AC cord holder on back, but once in a while while focused on something else or moving that big chassis on my small bench, I would brush up against it, and Bam!

[Steelwitch]

Did you record it? Reminds me of the Gerald Weber shock

nosaj

Is there a video of Gerald Weber getting shocked?

[nosaj]

Is there a video of Gerald Weber getting shocked?

Yea at the end of his video, in the outtakes where the credits are.

nosaj

[Leo_Gnardo]

Is there a video of Gerald Weber getting shocked?

What nosaj said. I'm sure the master of disaster is pretending for the camera.

[DrGonz78]

I think in that same video of him getting shocked he managed to also take out the rectifier tube. Mistakes happen hopefully they are the kind you can learn from... not much learning to be done if you're DONE.

Edit: actually there is that gag video where he pretended to get shocked, I think. Then there is a long video where his probe slips and he knocks out the rectifier.