What is that little ground wire for?

[spooney]

I've been inside quite a few amps that have had this tiny ground wire typically running from somewhere on the circuit board and connected to either the heatsink or a transistor clamp down. What is the purpose of this tiny wire. Its never large enough to carry any real current and I have also noticed that there are plenty of other amplifiers that do not have this wire at all.

[Andrew Eckhardt]

In an amplifier with an isolated sink it can only be to sap electrostatic charges or signals transfered to it capacitively from the transistor cases. What kind of amp? I've been in hundreds of amps and never saw that.

[spooney]

Recently I have seen it in an alpine mrv-1000 and a sundown audio sae-1200d. Can't think of anything else right off the top of my head but I have seen it quite a few times.

[Andrew Eckhardt]

Oh. I see this is under car audio. I've seen straps going from the boards to the sinks, but often they were pretty darn heavy. If you investigate the stuff connected to the other end of the strap you'll find out the designer's philosphy on chassis grounding.

[Perry Babin]

In most cases, it's there to shunt the high frequency noise from the sink to ground. Some amps (Rockford, others) make the connection from the board to the sink with a screw.

Some amps use parallel RC networks or simply capacitors in series with the wires. This helps prevent excessive current through the wire if the main ground is lost and the sink is bolted to the chassis of the vehicle.

[Andrew Eckhardt]

I think you'll find around 100 ohms and maybe a small capacitor on there. It's to pull the noise of the sinks like Perry said, without causing a serious ground loop if the sink is connected to the car body.

[1moreamp]

Yeah I can agree with all of the above but just some food for thought....What if a insulator was to breakdown and the rail was to get shunted through to the case of the amp.
Some of the more modern amps have over 120 volts inside them and that could sting mighty smartly if you became circuited between it and ground..

Remember the red and green wires of a phone can kill you under the right circumstances, and its next to nothing power wise. So its not a far stretch to imagine someone getting zapped by a ungrounded case of a high powered amp...Plus if the case was floating un-grounded it might transmit noise from the switching power supply like a antenna...
So the mini ground wire is for noise shielding and grounding of the case. It all follows good safety practices and theory. Also do not under-estimate how much voltage that tiny little jumper wire can carry, and because of its short length it can also carry a hefty amount of juice before it vaporizes like a fuse link.
I have replace so many of these over the years, I can not remember the total count. And its in most every amp ever made. Somewhere and somehow every sink has a ground connection. I also suggest you replace them as need be when your working on any of this gear, after all it was meant to be there...

[jol50]

Many of the power acoustik use a wire, that goes to a small cap. Some do use a screw, but if you don't screw the board down you have to use a wire...

[chipper]

Yeah I seen that aswell the Punch 800.2 has it from what i see right now. It's like a ground insulator.