WTF? Opus works without ground - I dont get it

**dmurray14** · 06-05-2005, 04:14 PM

I was messing with my setup today to try and see if I could eliminate my grounding issues, and I had the ground off the opus. I was surprised to see the opus was still lit up and powering the USB bus. Figured it was just residual power, but it didn't go off. So out of curiosity, I jumpered the BAT to the IGN and the computer started right up! I don't get it, how is it running without a ground?

Dan

**wizawuza** · 06-05-2005, 04:19 PM

any part of your case touching the car's chassis? Or perhaps the metal opus casing?

I know sometimes the casing of those things is connected to the ground.

**stevieg** · 06-05-2005, 04:25 PM

It could be finding ground a number of ways. It is likely to be through the sheilding (ground) on the audio cables.

**dmurray14** · 06-05-2005, 04:44 PM

Wow! That's scary! It was grounding through the VGA cable! Ugh, on goes the search for the grounding problems.

Dan

**stevieg** · 06-05-2005, 04:50 PM

This can happen EVEN IF you have a direct ground connection, and in fact is the common cause of grounding issues.

You need to ensure the route to ground on your actual ground cable is a lower resistance than any other paths to ground. As you probably know, it's usually achieved by having a short, fat, ground cable bolted to the chassis, that has the paint removed around it to ensure good good contact.