Video radio whine

I just installed a Boss DVD, Pyramid monitors and a Fm modulator in my truck. I am getting a whining sound related to engine speed when I play a DVD. I don't seem to get the whine when I play a Cd through the dvd player. I stopped a Best Buy and picked up a "ground loop" that installed in the rca connections between the dvd unit and the Fm modulator. I still have the whine but not as bad. Any ideas what to check?

Make sure you have a clean ground. In my experience, if the fm mod is metal and it is touching any ground source it has had engine noise. Also make sure that there are no power wires running within 18 inches of the rca's that feed the fm modulator.Certified Security Specialist

Always check info with a digital multimeter.

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If you have the power hard wired, you may also want to check the source.  I have found that some 12volt sources are not very clean when it comes to engine transients.  If nothing else works, and your vehicle is large enough to hide an UPS, I have had luck with them also. 

Ive had the same issue with mine lately and I used a ground loop isolator that goes in line with the power/ground of the fm modulator. It seems to knock it down a lot. Much better than the RCA style ground loop isolator. I managed to find one at Radioshack, ran me about 15 bones I think.  Also be sure like they said to isloate your power and rca's or you will get noise off of those as well. Another thing is if you can keep your ground sources to a minimum (use 1 ground source if possible) as well as keeping your ground short as possible will greatly reduce ground noise. Having several grounds (like a different ground for each monitor, dvd, etc) will give you lots of ground noise.  Try not to use anything  that has a coating on it such as a seat bolt or something like that. Usually they are galvanized or have some sort of dampening material on them to keep your vehicle nice and quiet :) Patrick

Apprentice Installer