[Subscribe to Daily Digest] |
 | [Main General Bulletin Board | BBFAQ |
Next by Date | Post Followup ]
Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos
Re: Ground loops? Posted by Randy Thatcher [Email]  (#22)  [Profile/Gallery]
(more from Randy Thatcher) on Thu, 25 Jul 2002 13:07:28
In Reply to: Ground loops?, Ian Whelan - mrfusion, Thu, 25 Jul 2002 12:34:53 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Ground loops are simple on paper, but a bear to fix sometimes. Basically voltage is measured as a potential from a ground point to the point in the circuit. In the case of a car (not a + ground, British/Lucas car), the sheetmetal/frame acts as a ground. The problem is that everything may not actually be at the same potential.
Let's take the example of a house. You have the ground prong that ties into pipes in the basement. So, in theory, all ground prongs are at the same potential. But there's a lot of wire, a lot of piping, perhaps some so/so connections, and metal does have some resistance. What's that give you? Pretty close to the same potential, but in some cases the the difference is more than negligable.
some folks will put guages in the car. I think the one I read about here is the Air/Fuel ratio which taps into the O2 sensor. If you ground the thing in the dash (like to the lighter) you'll get screwy readings. If you ground it up in the engine bay you'll get good readings. In theory they're the same ground, but in practice there's enough of a difference to cause problems.
Next, how did you wire up your audio system? When I put in blaupunkt head unit I just used a wiring harness from Crutchfield. All power and ground came from the standard wires. For my power amp (under back seat) I ran a thick fused wired from the battery, I ran a ground from the amp to a hole I drilled in some metal under the seat. I used a sheet metal screw and a lug connector to make sure I had a solid ground. Make sure none of the signal wire grounds (RCA Cables) are touching the metal. It works fine. I get a thump when I turn the stereo on after the car is on, but I think that's what happens when the amp is warm and then you give it the "ON" signal from the head unit.
check the grounds at the amp. Make sure your speaker and RCA connections are good, and make sure your wire isn't frayed or touching other metal.
Randy
posted by 63.161.86...
, Thu, 25 Jul 2002 13:09:33, Thu, 25 Jul 2002 13:07:28 <-- Viewing This Message, Thu, 25 Jul 2002 13:28:42
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
