The Fading Alt whine...yup "fading": is not a typo, plz help
 

Just finished updating an install on a 2003 SAAB95 Turbo. After starting the engine, I ran into the worst alt whine i've ever heard; but get this it stops after 15 minutes. Turn the car off and start it back up again and no alt whine. Let the car sit for a bit and BAM, it starts again then fades off? *CAN YOU SAY WHAT THE FCUK*

The system consists of a Pioneer P01(Japan)(same as P99) with an old school a/d/s px/a 8channel amp. 0/1 power from a new kinetik HD1400 power cell with factory alt. Custom rca's are ran opposite to the power. Ground is to the body under the rear seat with resistance of 0.02 and no electrical issues I can tell of with the car.

Pre-update: The system consisted of 3 zapco Dc's and JVC double din nav deck.Power and ground locations didn't change.

The owner did say he's heard the same thing once before on the previous system, but never returned till now.

I'm wondering if the alternator is FUBAR'D, since it's max output is 14.1v at 120km/h or 13.5v at idle.

No major trouble shooting has been conducted thus far, just looking for someone with good suggestions.

I hope it's not that amp....damn what a powerhouse.
thx

Julian

at idle you should have 14.3 - 14.5 volts at your battery. 13.5 volts is too low, what does your battery read with the motor off and the key in the off postion?

The battery read 12.9v after 20 hrs of charge with a cascade 55a power supply. off position after diving is 12.4v

sounds to me your battery needs replacing. after 20 hours of charging your battery's voltage should be higher then 12.9 volts, invest in a yellow top optima battery.

Anyone else? Dukk?

That's an interesting one dude. To check if it's the alternator, pull the belt off of it and see if the whine stops. Maybe it has a bogus connection that goes away when it heats up?

And I agree that the battery voltages seem a little off but then again, if the alternator is shot, they would.

I had an amp do that once, once it warmed up it would go away or diminish significantly. Make sure no metal from the heat synch comes in contact with the metal/frame of the vehicle (mounting screws).

Waiting to hear back from the owner whether if the Alt has suffered a heart attack or something.

Not touching the audio section until the electrical is addressed :D

Yep, that would be my second place to look. The amp may have a compromised solder joint in it that makes better connection when warm.

First guess is bad alt as others have said, second which was just mentioned..
being a vintage amp I would say it seems although either an inductor (more likely) or cap may be bad and once warmed is making it hard to troubleshoot. Caps are easy to identify but if you can check inductance when the amp is cold.