Rickresource Rickenbacker Forum

Yes, it is said that there are old amp techs and bold amp techs, but there are no old bold amp techs.

Please do not use the tongue discharge method.

But it's such a rush!

.....for a second or so.

If you're going to stick your fingers into an amp, then be sure they're all on the same hand.
One hand rule applies.

and, of course, the one tongue rule applies.

For those who don't know about the one hand rule: the idea is that you don't want to complete a circuit through your heart. If you have one hand on the chassis or colder part of the amp, and the other side on something like the high voltage, it is going to find the path of least resistance through your body. No need to experiment. It's how those electronic thingies work in audio.

Of course, even with only one hand, it's possible to complete the circuit to ground through your feet...

when working on my svt's i touch the chassis, touch the tip of my tongue on the heater duct above my head and stick my finger into the 600vdc cap lead ! this is the closest i'll ever get to owning a rick 4005 lightshow bass !

cjj wrote:Of course, even with only one hand, it's possible to complete the circuit to ground through your feet...

But to have a ground path to ground(earth) you'd have to have it plugged in to an outlet.

Or have chassis sitting on a suitably conductive surface...

Eh, just lay your tongue across the cap leads....

Would a custom cable, connecting just the ground lug of the amps power input to just the ground of the wall outlet, provide the least path of resistance?

whojamfan wrote:Would a custom cable, connecting just the ground lug of the amps power input to just the ground of the wall outlet, provide the least path of resistance?

If I understand your question, then that is exactly what the green ground wire in a regular power cord does. Now, as to path of least resistance, anyone who has touched lip to a mic or grabbed the mic stand while holding the strings and felt "the power" will argue that point. Of course that is more from the days of two prong power cords.

johnallg wrote:

whojamfan wrote:Would a custom cable, connecting just the ground lug of the amps power input to just the ground of the wall outlet, provide the least path of resistance?

If I understand your question, then that is exactly what the green ground wire in a regular power cord does. Now, as to path of least resistance, anyone who has touched lip to a mic or grabbed the mic stand while holding the strings and felt "the power" will argue that point. Of course that is more from the days of two prong power cords.

Quite often, an amp's input/instrument GND is right to the chassis, which does have some very small resistance to the "earth" GND from the wall through the chassis, itself. In general, this is probably a good thing.

A thing that's really hard for a lot of people to pick up is that "GND" isn't really 0 volts. It is a reference return for a circuit that can move substantially from where 0 volts would be- circuit to circuit and chassis to chassis. The worst shock problems on stage occur when 1) a tube guitar amp has 2 wires from the wall (or uses a 3-2 adapter)- this means high voltage can move the ground substantially at will. 2) there is a clipped or unconnected ground in the guitar or instrument input. 3) there is an improperly wired outlet from the amp or in the PA- or some disagreement between equipment about what GND, pos and neg are (this is how I no longer have my wonderful Vox Continental organ anymore). 5) when there is a cap or other part failure in a piece of equipment.

I have had some shocks from mics on PA's where they took a 3-2 adapter for ground and blew up my Continental when plugging it in where sockets did not agree about GND, pos and neg. I did live to talk about it.

I always questioned to wisdom in grounding the strings on an instrument.

It's really so you're not the ground return to earth to complete the circuit.

I think it was my brother who told me when I was a young person, "if the amp doesn't know where its ground is, it's probably you."

Caution is a good thing.

-Mark