I think that the construction of a version 3 MS in the standard MS case connects the grounded heat sink rail to the case. When the case is fastened to the body, it seems like it may provide an alternate path for ground currents from the engine to the body (or vise versa) that are not related to the MS operation. This may add noise that could disrupt or perhaps even damage the MS.

I'm building a version 3 board in an OEM case, not the MS case, and can either connect the heat sink to the case or isolate it. If I isolate it, leaving the MS signal ground isolated from the case ground, then I think the only current running through the MS ground wires is for MS signals. This seems better to me. Comments?

Thanks,

 

I agree... although I'm no electrical engineer.... I think doing things this way is a good idea to help avoid ground loops

 

For the standard MS build I think the heat sink is supposed to be in good contact with the case to provide additional thermal cooling.

I've already built a MS in the OEM case and have the heat sink in contact with the case. I've been running fuel only with the MS and so far no ground related issues.

I think if you have good grounds thru the standard MS gound wires you should not have any problems.

Scott