Big problem that does’t make sense, deck

BTW, "earth" is the first thing you should hook up, not the last !!!!Kevin Gerry

Certified Electronics Technician

MECP First Class Installer

Owner/Installer

Classic Car Audio

since 1979

Search on my username in this forum and you will see that I recently had issues with a thump noise. I tried the same trouble shooting techniques that you did with the same results. I attacked it again last night and I think I found the problem which, in turn, may be your problem because the symptoms sound the same. My system can be seen here for reference. My amp was mounted on a sheet metal box and the box was screwed into the sheet metal of the truck which, in turn, grounded the box. The screws I used to secure the amp to the sheet metal box also provided continuity to ground through the amp chassi via the sheet metal box. Also, part of my seat's brackets were rubbing/scratching on the frame of the amp which provided another point of ground. Basically, my amp was grounding in two or three spots at once which, according to tech support at Alpine, can cause the head unit to go in and out of safe mode inducing a thumping noise in the system. Last night I insulated my amp from the sheet metal box and surrounding seat supports using rubber material. I even put rubber under the screw heads to make sure they can not contact the amp. I checked for continuity to ground all over the amp surface and added rubber until I got zilch, nada, nothing. So far today - no problems. Not even a hint of a thump noise. I say all of this to ask you to check and make sure your amp is gounding only at one point. That point should be the ground wire. This will avoid any ground loops that will induce popping sounds in the system. My 2 cents (based on experience). Mike 2000 F150 Supercab Lariat, Alpine CDA-9831, Polk MMC570 in Doors, One Polk MM2104 Sub, One Polk Carbon C400.4 Amp.

John 3:16

kgerry..one of the first things I learnt when I got my first job in the industry Check all advice given with a meter

overworked2 wrote: I connected the power leads, speakers, antenna and was looking around for a spot to earth the unit out too

Kevin Gerry

Certified Electronics Technician

MECP First Class Installer

Owner/Installer

Classic Car Audio

since 1979

overworked2 wrote: "I've had similar trouble as well, goes back to my very first install".........."Another drama I had with that car that scared the daylights out of me was when I installed the head unit, I connected the power leads, speakers, antenna and was looking around for a spot to earth the unit out too "....

Check all advice given with a meter

does everyone in australia say "earth" instead of ground, or are you just trying to be trendy? because it's not clever, witty or catchy. just curious. now im done.

soundmasta:  it's really "earth".  We in the US say "ground".  All in all, if anybody's guilty of being trendy....it's us in the USA.  The peoples of other cultures seem to be a little more down to "earth"!Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Just to add real quick. My 1990 Prelude had a noise issue, not one like this but it was a noise through the speakers. I ran the RCA's down the passangers side and the power down the drivers side. Also, when mounting the amp i put Rubber feeties so to speak so the amp wouldnt be connected to the chasis. Also on the ground make sure u sand it down and have no paint where it is. Sorry if I repeated something but this is my experience.