Alpine CDA-9831 Woes

In previous posts I had asked for help in finding the source of a random "thump" noise that I hear from time to time. Last night I decided to check grounding continuity as explained in the sticky "What is proper grounding" located in this forum. Everything checked out fine. I put everything back together and tested the system before going to bed. Everything was good. This morning, drove to work listening to my favorite disc and pulled up into the parking lot before the song finished. I turned the truck off and rotated the key backwards to "ACC" so I could listen to the rest of the song. Strange thing happened - only the sub channel was working. My door speakers were dead. Even more strange is the fact that the front speakers are running off amp power and the rear door speakers are on head unit power. Both sets of speakers were dead which, to me, rules out the amp as the problem. I had the to hit the "reset" button on the head unit to make the speakers come on again. I haven't a clue as to why this happened. Any ideas from the members here will be appreciated. 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

Wish I could help you out here...I have a 9831 and have had nothing like you describe happen. Are the front speakers on a separate amp from the subs? What is your voltage when the key is turned to the ACC position? Is it possible that your sub amp is taking most of the battery power when you have the truck in the ACC position? I have an 01' Silverado and the stereo keeps playing until I open the door when I turn off the truck so I never put it in the ACC position. Do you really need the rear speakers? Try disconnecting them and see if you have the same problem. Maybe it's something in the HU amp which is causing a conflict.

sounds like you've got something wired to IGN not ACC.....Kevin Gerry

Certified Electronics Technician

MECP First Class Installer

Owner/Installer

Classic Car Audio

since 1979

Problem solved. Looks like I was having a gound loop through the chassi where the amp was mounted. Added some insulation between the amp and chassi (rubber mat) and all is well. Mike2000 F150 Supercab Lariat, Alpine CDA-9831, Polk MMC570 in Doors, One Polk MM2104 Sub, One Polk Carbon C400.4 Amp.

John 3:16