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BarryA 29th April 2012 01:03 AM

Alpine 3552 amp issues
Newbie here, and NOT an audio expert by any stretch of the imagination, although I do have quite a bit of experience with automotive electrical systems, and have installed more than a few audio systems in vehicles over the years.

Issue in this case is audio "drop out" that appears to be in some way linked to an issue with the amp - with the system powered up and audio coming out of the speakers, the "Power Protection Circuit" indicator light is green, but it changes to red or red-orange when the audio cuts out. Issue does not appear to be vibration related, as the problem occurs at random whenever the system is on, even sitting still in the garage with the engine off.

This system is in my wife's 1982 BMW 633 CSi, and is many years old - the original Alpine head unit was non-operational when we bought the car 6 years ago, so a new Pioneer head unit was installed; since then the system has worked flawlessly until about 2 months ago when this issue started. Unfortunately, there was no amplifier manual with the car, and so far I have not located one on the web.

Any thoughts as to troubleshooting this would be greatly appreciated (I don't intend to get into internal diagnostics on the amp itself).

Barry Allen
Fair Oaks CA

Old'n'Cranky 29th April 2012 01:54 AM

the audio will stop when the amp goes into protection.

shorting speaker wires ?
dirty power or fuse lines ?

start with the basics.

BarryA 29th April 2012 03:32 AM

Not familiar with how the "protection" circuit is set up...
would an "open" in a speaker lead be likely to trigger it the same as a grounded lead?

In this car, there are a pair of 1" tweeters mounted high in the doors - I've had other issues with the wiring bundle into the driver's side door previously (erratic power mirror operation, etc), so if an open in the leads to the tweeter in the driver's door would be likely to trigger the protect function, that's probably a logical place to start.

Perry Babin 29th April 2012 03:47 AM

If the tweeters use 12db/octave crossovers, an open connection between the tweeter and the crossover could cause the amp to go into protection.

BarryA 29th April 2012 07:26 PM

Thanks - not sure whether the crossovers are inside the doors or behind the front
kick panels - will find out when I start pulling things apart. If the crossovers are inside the kick panels, that would further argue for replacing the leads in the wire bundle going into the door..........

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