alpine head unit amp problem

[brianlanning]

I have an alpine head unit. It's one of the cheaper ones. It's maybe
3 months old. I have it hooked up to coax speakers in the back through
the amp in the head unit. The sub rcas go to an amp and two 10s in the
trunk. I have two more amps on order to drive the coax speakers. But
I have to tolerate my problem for another week while they get here.

I used to be able to crank the system just like this and get plenty
loud. Now, it's acting like the amp is overheating and shutting down.
With all four speakers going, I can play it at a reasonably loud, but
normal listening level for maybe 5 or 10 minutes. Then it starts to
cut out. Then it goes out completely leaving only the subs going. I
can turn it off for 5 or 10 minutes, then it works again. If I fade
the speakers all the way to the front, it lasts much longer, maybe 45
minutes. But it will eventually shut down.

This is new behavior, only within the last two or three weeks. I
haven't changed anything. It worked for a couple months without ever
shutting down no matter how loud I played it. I can feel the heat sink
in the back of the hu. Sometimes it's really hot when it shuts down.
Other times, just warm. There seems to be enough airflow back there.
The heater's not on so it's not blowing on the back of the hu.

So the question is, did I hurt it somehow? I would think it would just
fail completely if I did. I guess I don't care much because I won't be
using the inboard amp after this weekend. So what's happening?

brian

[MOSFET]

Did you make any alterations to your system before this started happening?

For instance, did you remove your HU for some reason and then put it back
and THEN the problem started? It's possible your HU is not getting a good
ground anymore, that might cause this problem.

The FIRST thing, however, that ran through my head is that you might have
your speakers bridged (your driving two sets of speakers with one output) so
that your HU is seeing a 2 ohm load. But you seem like the kind of guy who
knows what he's doing so I doubt you've gone and done this.

So, if I were you, the first thing I would check is the input voltage at the
HU. Make sure it is getting AT LEAST 11-12 volts. Your sub amp may be
drawing so much current that perhaps your car voltage is dropping too low.
That would CERTAINLY cause your HU to shut down it's internal amps (or shut
down completely). Check that out first with a voltmeter. If that is fine,
make sure your HU is getting a good ground.

If both of those are fine, it may be a problem with your Alpine, but as you
said, it may not matter when you go with all external amps.

MOSFET
"brianlanning" > wrote in message
oups.com...
> I have an alpine head unit. It's one of the cheaper ones. It's maybe
> 3 months old. I have it hooked up to coax speakers in the back through
> the amp in the head unit. The sub rcas go to an amp and two 10s in the
> trunk. I have two more amps on order to drive the coax speakers. But
> I have to tolerate my problem for another week while they get here.
>
> I used to be able to crank the system just like this and get plenty
> loud. Now, it's acting like the amp is overheating and shutting down.
> With all four speakers going, I can play it at a reasonably loud, but
> normal listening level for maybe 5 or 10 minutes. Then it starts to
> cut out. Then it goes out completely leaving only the subs going. I
> can turn it off for 5 or 10 minutes, then it works again. If I fade
> the speakers all the way to the front, it lasts much longer, maybe 45
> minutes. But it will eventually shut down.
>
> This is new behavior, only within the last two or three weeks. I
> haven't changed anything. It worked for a couple months without ever
> shutting down no matter how loud I played it. I can feel the heat sink
> in the back of the hu. Sometimes it's really hot when it shuts down.
> Other times, just warm. There seems to be enough airflow back there.
> The heater's not on so it's not blowing on the back of the hu.
>
> So the question is, did I hurt it somehow? I would think it would just
> fail completely if I did. I guess I don't care much because I won't be
> using the inboard amp after this weekend. So what's happening?
>
> brian
>

[Captain Howdy]

Before running coax speakers, you need to rub the speakers down with coax wax
so that they are not so stiff and overload the amp powering them.


In article >, "MOSFET"
> wrote:
>Did you make any alterations to your system before this started happening?
>
>For instance, did you remove your HU for some reason and then put it back
>and THEN the problem started? It's possible your HU is not getting a good
>ground anymore, that might cause this problem.
>
>The FIRST thing, however, that ran through my head is that you might have
>your speakers bridged (your driving two sets of speakers with one output) so
>that your HU is seeing a 2 ohm load. But you seem like the kind of guy who
>knows what he's doing so I doubt you've gone and done this.
>
>So, if I were you, the first thing I would check is the input voltage at the
>HU. Make sure it is getting AT LEAST 11-12 volts. Your sub amp may be
>drawing so much current that perhaps your car voltage is dropping too low.
>That would CERTAINLY cause your HU to shut down it's internal amps (or shut
>down completely). Check that out first with a voltmeter. If that is fine,
>make sure your HU is getting a good ground.
>
>If both of those are fine, it may be a problem with your Alpine, but as you
>said, it may not matter when you go with all external amps.
>
>MOSFET
>"brianlanning" > wrote in message
oups.com...
>> I have an alpine head unit. It's one of the cheaper ones. It's maybe
>> 3 months old. I have it hooked up to coax speakers in the back through
>> the amp in the head unit. The sub rcas go to an amp and two 10s in the
>> trunk. I have two more amps on order to drive the coax speakers. But
>> I have to tolerate my problem for another week while they get here.
>>
>> I used to be able to crank the system just like this and get plenty
>> loud. Now, it's acting like the amp is overheating and shutting down.
>> With all four speakers going, I can play it at a reasonably loud, but
>> normal listening level for maybe 5 or 10 minutes. Then it starts to
>> cut out. Then it goes out completely leaving only the subs going. I
>> can turn it off for 5 or 10 minutes, then it works again. If I fade
>> the speakers all the way to the front, it lasts much longer, maybe 45
>> minutes. But it will eventually shut down.
>>
>> This is new behavior, only within the last two or three weeks. I
>> haven't changed anything. It worked for a couple months without ever
>> shutting down no matter how loud I played it. I can feel the heat sink
>> in the back of the hu. Sometimes it's really hot when it shuts down.
>> Other times, just warm. There seems to be enough airflow back there.
>> The heater's not on so it's not blowing on the back of the hu.
>>
>> So the question is, did I hurt it somehow? I would think it would just
>> fail completely if I did. I guess I don't care much because I won't be
>> using the inboard amp after this weekend. So what's happening?
>>
>> brian
>>
>
>

[brianlanning]

MOSFET wrote:
> Did you make any alterations to your system before this started happening?

No. That's why I said:

> > This is new behavior, only within the last two or three weeks. I
> > haven't changed anything.

:-)


> For instance, did you remove your HU for some reason and then put it back
> and THEN the problem started? It's possible your HU is not getting a good
> ground anymore, that might cause this problem.

Really? I suppose that's possible. Maybe the screw I used for ground
has loosened. The entire hu doesn't shut down though, just the amp.
The hu still drives the sub amp when this happens.


> The FIRST thing, however, that ran through my head is that you might have
> your speakers bridged (your driving two sets of speakers with one output) so
> that your HU is seeing a 2 ohm load. But you seem like the kind of guy who
> knows what he's doing so I doubt you've gone and done this.

Yeah, I thought this too. Looked and looked and looked again. I'm
running the speakers through the factory wiring. I know that can cause
problems, but at least I can look at the factory wire colors to keep
everything straight. I have new wire run for the amps that should be
here this weekend.


> So, if I were you, the first thing I would check is the input voltage at the
> HU. Make sure it is getting AT LEAST 11-12 volts. Your sub amp may be
> drawing so much current that perhaps your car voltage is dropping too low.

>From a hu amp? And the sub amp is loafing when this happens. I used
to keep the volume around 22 or 23 (I know these numbers are
meaningless) but now it happens even around 8 or 9. That's a volume
where I have trouble hearing the music. I can get through a couple
songs, then it fails every song.

> That would CERTAINLY cause your HU to shut down it's internal amps (or shut
> down completely). Check that out first with a voltmeter. If that is fine,
> make sure your HU is getting a good ground.
> If both of those are fine, it may be a problem with your Alpine, but as you
> said, it may not matter when you go with all external amps.

I'll tighten the screw. That could easily be what's happening. It's
grounded to a bit of metal in the dash. But that piece of dash may not
be grounded to the rest of the car too well. I'll see if I can find
another bolt.

Yesterday, I reached behind the hu and disconnected the wiring harness.
I pulled it out and looked for exposed wires or something that might
be causing a short. When I put it back together, I thought I had
"fixed" it. It played all the way home for maybe 45 minutes at a
higher volume than I had been able to achieve since the problem
started. It came back though. Maybe moving the ground wire around
would explain this.

brian

[Eric Desrochers]

The internal fan failed?

--
Eric (Dero) Desrochers
http://homepage.mac.com/dero72

Hiroshima 45, Tchernobyl 86, Windows 95

[brianlanning]

Eric Desrochers wrote:
> The internal fan failed?

There isn't one.

brian

[brianlanning]

MOSFET wrote:
> For instance, did you remove your HU for some reason and then put it back
> and THEN the problem started? It's possible your HU is not getting a good
> ground anymore, that might cause this problem.

At first, I thought this was the problem. So I grounded the hu to the
cig lighter ground. It worked fine for a while but the problem
returned.

> So, if I were you, the first thing I would check is the input voltage at the
> HU. Make sure it is getting AT LEAST 11-12 volts. Your sub amp may be
> drawing so much current that perhaps your car voltage is dropping too low.

It's possible. I have the hu wired into the power source that the
original factory hu was using. It probably is drawing more current
than the factory unit was. But wouldn't I blow the fuse before the
internal amp would shut down? Maybe not. It looks like the rest of
the hu is totally happen when the amp shuts down. It looks to me like
the real solution is the external amps I ordered.

> That would CERTAINLY cause your HU to shut down it's internal amps (or shut
> down completely). Check that out first with a voltmeter. If that is fine,
> make sure your HU is getting a good ground.

it's around 12.5 volts.

It might be a dud but as long as it's powering the preamp outs, I
probably don't care as long as the rest of the hu keeps working, which
it looks like it is.

brian