My Car's amp randomly turns off....

[Accipiter22]

alright, here's the situation....I got an amp and a couple subs in my trunk, same setup that I've had the last 6 years. Over the last 6 weeks or so, the bass randomly cuts out. a VAST majority of the time it's when i first start up the car, (like 97% of the time). Now, the amp has MOSFET on it. When I start up the car, and then run to the back of hte car to look at the amp, it's lit as if it has power, but the red 'Protect' light is on.....thus no bass. Here's the weird thing though, if I firmly tap the amp with my hand, (nothing too hard) SOMETIMES this fixes the problem, i.e. bass starts coming from my subs again.

The ground is securely attached, all wires leading into the amp are firmly secured in the amp, all speaker wires to the subs are secure at both ends. This confuses me, because if it's in Protect mode, tapping the thing shouldn't bring it out of that...do you think something's loose in there?

What say ATOT?

 

[jjoyner]

Turn it back on....
/fixed

 

[Accipiter22]

Originally posted by: jjoyner
Turn it back on....
/fixed

I wish that was the problem

 

[nboy22]

Loose ground wire? that's what it sounds like.
all the problems I've ever seen like this are due to a loose ground wire...

 

[Kyle]

my thoughts were the ground but if thats secured and metal on metal then I dont know...if its a nice amp it might be worth sending off to repair
I've used this place
came back working great.

 

[FoBoT]

does it smoke or burst into flames?

 

[jjoyner]

Originally posted by: FoBoT
does it smoke or burst into flames?

LOL

We have a winner

 

[nboy22]

Oh yeah.... is the inline fuse by the battery still in tact? I would check that next, it might be blown and/or barely making contact or something. But.. if tapping the amp does something maybe something is fried? not sure.

 

[MrBaseball]

We had to send a car amp (JBL BP1200.1) in to get fixed when it started doing this. It worked great when we got it back.

 

[AlienCraft]

Open it , check to see that all connections are secure, especially where the power transistors connect to heat sink. If they're loose, get some silicone heat sink grease and coat liberally. Chances are the dissimilar metals are oxidizing, making an intermittant connection.

 

[Ns1]

i would guess that it's overheating, happened to my amp

 

[AnonymouseUser]

Originally posted by: NeuroSynapsis
i would guess that it's overheating, happened to my amp

Yes, that was my guess also.

Until I actually read the post, duh.

 

[Farbio]

sounds like a loose wire from what you said...the protect light almost always means bad ground loop? maybe some strands came loose and are touching the power wire when they come into the amp?

 

[Accipiter22]

Originally posted by: AlienCraft
Open it , check to see that all connections are secure, especially where the power transistors connect to heat sink. If they're loose, get some silicone heat sink grease and coat liberally. Chances are the dissimilar metals are oxidizing, making an intermittant connection.

I was thinking I'm probably going to have to open it up....your post makes sense, it would explain why tapping the thing makes it work again, cause there's no loose wired on any of the connections, the ground is fastly connected to some bare metal....and I doubt it's the inline fuse at hte battery since tapping the amp fixes the problem sometimes. I will check the inline fuse tomorrow, and if not that, I"ll open up the amp....what should I look for? will it be obvious?

 

[spidey07]

you have a short somewhere.

on the speaker leads or on the power leads most likely.

Or, as you desribe it works fine once the car is started meaning you have an inrush of current and the short/problem is outside of the amp/speaker wiring.

-edit- after reading that you tap the amp and it seems to do OK, its probably on the board of the amp. Send back for repair or get a new on if it can't be fixed for cheap or under warranty.

Its my opinion that an amp (car or home) can never be fully repaired and will always be troublesome.

 

[Accipiter22]

Originally posted by: spidey07
you have a short somewhere.

on the speaker leads or on the power leads most likely.

Or, as you desribe it works fine once the car is started meaning you have an inrush of current and the short/problem is outside of the amp/speaker wiring.

-edit- after reading that you tap the amp and it seems to do OK, its probably on the board of the amp. Send back for repair or get a new on if it can't be fixed for cheap or under warranty.

Its my opinion that an amp (car or home) can never be fully repaired and will always be troublesome.

yah, it's 6 years old, and I'm worried that if I open it up, it'll never work again, but as it is right now it's getting pretty annoying

 

[imported_griffis]

With past experience with amps and considereing it's age, I would invest in either a new amp or getting it fixed. Buying a new one WILL be cheaper GL

 

[dabuddha]

Check the fuse under the hood. That was the problem with my amp. It was a fuse placed in the wiring to the battery that was causing my amp to cut out.

 

[Accipiter22]

Originally posted by: griffis
With past experience with amps and considereing it's age, I would invest in either a new amp or getting it fixed. Buying a new one WILL be cheaper GL

yah I was thinking of a more powerful mono amp...I"m using this old jensen 2 channel 500 watt, 600 peak amp. Honestly I figured I'd upgrade early on when I first built the system, but it performed so well over the years and was so loud I just kept it. what I may do is get a new mono amp for my subs. After I do that I'll take my current one and use it to power my rear speakers

edit: I mean fix my current one before using it on my rear speakers

 

[Slvrtg277]

Originally posted by: Accipiter22

Originally posted by: griffis
With past experience with amps and considereing it's age, I would invest in either a new amp or getting it fixed. Buying a new one WILL be cheaper GL

yah I was thinking of a more powerful mono amp...I"m using this old jensen 2 channel 500 watt, 600 peak amp. Honestly I figured I'd upgrade early on when I first built the system, but it performed so well over the years and was so loud I just kept it. what I may do is get a new mono amp for my subs. After I do that I'll take my current one and use it to power my rear speakers

So that your rear speakers can go out on you?

 

[Accipiter22]

Originally posted by: Slvrtg277

Originally posted by: Accipiter22

Originally posted by: griffis
With past experience with amps and considereing it's age, I would invest in either a new amp or getting it fixed. Buying a new one WILL be cheaper GL

yah I was thinking of a more powerful mono amp...I"m using this old jensen 2 channel 500 watt, 600 peak amp. Honestly I figured I'd upgrade early on when I first built the system, but it performed so well over the years and was so loud I just kept it. what I may do is get a new mono amp for my subs. After I do that I'll take my current one and use it to power my rear speakers

So that your rear speakers can go out on you?

lol I meant try to fix my current one then use it to power my rear speakers...I should probably edit that

 

[Slvrtg277]

Originally posted by: Accipiter22

Originally posted by: Slvrtg277

Originally posted by: Accipiter22

Originally posted by: griffis
With past experience with amps and considereing it's age, I would invest in either a new amp or getting it fixed. Buying a new one WILL be cheaper GL

yah I was thinking of a more powerful mono amp...I"m using this old jensen 2 channel 500 watt, 600 peak amp. Honestly I figured I'd upgrade early on when I first built the system, but it performed so well over the years and was so loud I just kept it. what I may do is get a new mono amp for my subs. After I do that I'll take my current one and use it to power my rear speakers

So that your rear speakers can go out on you?

lol I meant try to fix my current one then use it to power my rear speakers...I should probably edit that

I'd suggest just getting rid of it instead of fixing it. Truthfully, it's not that great of an amp to begin with and this may be the sprinkle before the downpour.

 

[loic2003]

Slap a multimeter on the input cable and get someone to start the motor. You may be getting some kind of spike when the car is started from a dodgy altinator or regulator.

Just an idea. The reason the thing goes into 'Protect' is because something is happening that could cause damage, possibly too much voltage or perhaps a short in a cable going to the speakers.

Basically, check all the cabling to and from the amp with the mulitmeter (check resistance) and check input voltages and current going to the amp.

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