Need help desperatly concerning electrical gremlins on Alpine 4 channel amp

[KungFuPimp]

I'm at my wits end trying to figure this problem. I don't know it's my amp, battery, or alternator.

I have one Kicker sub amp and one Alpine 4 channel amp. The problem lies with the 4 channel amp, it keeps turning on and off. It only happens randomly. I have checked all connections and they are tight. I checked all fuses and they are good. I also have relocated the ground for the 4 channel amp but the problem still continues.

I have checked the voltages multiple times and there are the results :

All measurements are at car idle.

Both amps on : 13.79 volts - 13.81 volts

Both amps on and AC running : 13.79 volts

Both amps on, AC running, and rear window defroster on : 13.69 volts

Both amps on, AC running, rear window defroster on, and wipers running : 13.69 volts

Both amps on, AC running, rear window defroster on, wipers running, and headlights on : 12.32 volts

There's another wrinkle in my problem. When the 4 channel amp is turning on & off, the voltage at the battery and at the 4 channel amp would fluctuate between 11.50 volts and 12.75 volts. The sub amp is always on regardless of the 4 channel amp problem.

When the 4 channel amp finally turn on, stay on, and have sound output, the battery voltage would stay at a constant 14.17 volts.

Is this a sign of my battery about to die ? Or signs of an alternator about to die ? Faulty voltage regulator ? 4 channel amp about to die ?

I have gone to numerous Auto Zone and O'Reilly's to have my electrical system checked out and all of them said that my charging system is okay. But I would like to have your input.

If it's the alternator, is it advisable to get a high output alternator ? And if I do get a high output alternator, do I need to up the fusible link amp rating ?

BTW, these two amps are installed on my 300ZX with a factory 80 amp alternator.

Any help would be greatly appreciated....Thanks !

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[All_Logix 10+ year member]

I really don't think your problem lies within the electrical system and there are a couple of reasons why, the most obvious of which being, why is it constantly the 4 channel giving you problems in these power fluctuations. Secondly, I am assuming the major flux comes instantaneously when the amp cuts off, if that is the case it could be an issue with the meter your using trying to keep up with the transient response of the circuit, but that is neither here nor there. I am willing to bet the problem is something to do with the amp itself, have you tried bench testing it? How often does it cut out and for what period of time does it stay off? Also this is somewhat far fetched, but I have seen it, make sure there isn't a signal sense turn on application on the amp that has gone haywire.

 

[KungFuPimp]

Thanks for responding so quickly. Sometimes the amp would cut out for 24 hours, sometimes for 15 mins...it's just no telling. It just does it very randomly. The amp is an Alpine MRP-F200. I have this exact setup in the same car for the past 8 years. The only thing I have changed in the last 8 years of this set up is add more sound deadening and change out the head unit.

Since I have two amps, I wired in a relay from the head unit remote to turn on both amps (same setup before the head unit change).

This morning when I started the car, the 4 channel amp's power led came on and then fades out, then comes on, and then fades out. This afternoon when I stepped out for lunch, the 4 channel amp turned on and have sound through the speakers but after driving the car for 15 mins, the amp would go into the led come on and fade out cycle.

I checked the voltage input when it was doing that, the voltage range was 12.95 volts to 13.65 volts.

Please point me in the right direction because I want to fix the real problem instead of blindly throw money at it.

Thanks again !

 

[All_Logix 10+ year member]

Take the amp to your local shop and have them bench test it. If you find the right guys who are really interested in helping you they generally wont charge you much for this type of stuff in hopes that you will return for future purchases