Help with piezo bass bridge

[MarkusBass]

I'm looking for some help with a piezo bass bridge. I'd like to test it with a piezo buffer I'm designing but I'm not sure how it should be connected. It seems that the ground wire is not connected in any way nor to the bridge, nor to piezo transducers (I can lift the printed circuit board and there is no connection underneath it). Do you have any idea how it should be connected? Without connection to the bridge it does not work. When I connect the ground wire to the bridge it starts working but there is huge amount of strange noises. What is interesting the bridge used to work in some bass guitar but I don't know how it was connected then. There is a BEQ06 symbol on the bridge but I cannot find it on the internet. Any ideas?

PS: I assume that a piezo bridge is kind of a pickup :-).

Mark

[David King]

Mark,

Try grinding away some chrome plating from the bottom of the bridge, you may find a thin layer of copper plating you can solder to. If not you can put some copper foil on the bass under the bridge and solder your wire to that. You may need the strings on and tensioned to get a solid connection between the saddles and the base plate. I would connect the shield of the coax to ground in the control cavity so that the signal wire is shielded from the other end.

[MarkusBass]

Thanks,

I will try it although I think this is something that I already tested. I conected the ground of the bridge to the coax cable with a screw but maybe it did not have good contact. I'll try to test it differently.

Mark

[David King]

The plating will cause no end of problems, you need to get down to the base metal which in this case is "white metal" aka pot metal. It's easy and cheap for die casting but terrible for conductivity because it corrodes very quickly.

[MarkusBass]

Mark,

Try grinding away some chrome plating from the bottom of the bridge, you may find a thin layer of copper plating you can solder to. If not you can put some copper foil on the bass under the bridge and solder your wire to that. You may need the strings on and tensioned to get a solid connection between the saddles and the base plate. I would connect the shield of the coax to ground in the control cavity so that the signal wire is shielded from the other end.

Thanks David,

You were gentle by saying that "you may need the strings..." . Actually, this is required. The tranducers do not have a separate wire for the ground connection. So only with strings on you can have a solid ground connection. And without it the bridge does not work at all.

Thanks again,
Mark