Hi folks.

I'm an amatuer; I've installed a few decks, speakers, amps etc over
the years, but still know little when it comes to complicated
electrical and troubleshooting. I have a problem that's got me
stumped.

I have a 17 year old car ('87 Porsche 928) that I installed an Alpine
9811 HU in that is cutting out.

I've been trying to troubleshoot and isolate the problem, but can't
figure it out.

I installed the Alpine 9811 HU about a year ago replacing an old
Alpine tape deck/cd changer combo HU. (I'll note here that the old
unit was using the factory wiring for power, so that's what I did with
the 9811 instead of the mfr recommended direct to battery.) It worked
great for about 6-9 months, then after a non-electrical mechanical
project (timing belt job), it started cutting out.

Since it occured when I did the TB job, I assumed they had to be
related. I checked all the cars' fuses, all checked out. I had the
alternator checked and replaced the battery. Everything on the car
looked in check.

My second inclination was that the amplifier blew a fuse. All
speakers were wired from the amp (Amp was getting line level RCA from
the HU), so I removed the amplifier from the equation and ran the
speakers directly from the HU using the HU speaker outputs. That
didn't affect the problem.

During this process, though, I had to pull the HU and I noticed that
the heat sink on the 9811 was getting hot, then cutting out. And the
tiny fan on the heat sink on the back was never turning on, not sure
if its supposed to (I assume so, otherwise why's it there?).

I thought at this point the deck could be broken, so I thought I'd try
operating the unit outside the car to double-check. So, I took the
unit out, wired the power and ground to a battery jumper unit (like a
battery with built in jumper cables), and hooked one of the speaker
outputs to a subwoofer I had lying around to see what happened. The
unit didn't cut out even with high volume after several minutes. The
heat sink was still very hot and the tiny fan on the heat sink still
never came on. But it worked.

I've read that the 9813 and other alpines with the internal v-drive
amps should be run directly to battery because they draw more power,
but my 9811 doesn't have the v-drive.

Could it be I just need to go directly to battery power?
Maybe the unit's overheated and needs to be repaired?
Maybe I need a better ground than the factory harness is providing?

I appreciate any suggestions.

Perx
Huntington Beach, CA