Problem with Pioneer DEH-P760MP (car audio)

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Hi,
I have a car audio Pioneer DEH-P760MP unit and it was working fine for
a couple of months until today. I started the car's engine (while I
was hearing music), moved 3 feets and turn off the engine (and the
audio unit turn off too) and then I started the engine again but the
sound was dead. I mean, the unit works fine and I can see all the
screen information, even I can hear the subwoofer unit, but the sound
from the 4 speakers is dead. The four speakers are connected directly
to the pioneer unit without an amp, so I think maybe the internal amps
blowed but the unit doesn't smell of burn. The unit was heat, but not
as much to burn. An internal blowed fuse (the external fuse is ok)?
The 4 speakers are ok (4 ohms) and the car's preamp output is also ok.
Somebody know how to fix this?

[joe.ker]

Check all your speakers and the speaker leads. it sounds like one of your
speaker lines are grounding out. It's possible that the internal amp on the
unit has gone out, but in most cases when something like that happens, it is
a speaker grounding out. Sometimes it is just one of the speaker terminals
touching metel ot the head unit may have pinched a speaker lead when the
unit was installed and over time has rubbed through the wire.

what year, make and model vehicle do you have. have you added aftermarket
speakers?

--
The Clown Prince of Car Stereo


> wrote in message
oups.com...
> Hi,
> I have a car audio Pioneer DEH-P760MP unit and it was working fine for
> a couple of months until today. I started the car's engine (while I
> was hearing music), moved 3 feets and turn off the engine (and the
> audio unit turn off too) and then I started the engine again but the
> sound was dead. I mean, the unit works fine and I can see all the
> screen information, even I can hear the subwoofer unit, but the sound
> from the 4 speakers is dead. The four speakers are connected directly
> to the pioneer unit without an amp, so I think maybe the internal amps
> blowed but the unit doesn't smell of burn. The unit was heat, but not
> as much to burn. An internal blowed fuse (the external fuse is ok)?
> The 4 speakers are ok (4 ohms) and the car's preamp output is also ok.
> Somebody know how to fix this?
>

[[email protected]]

joe.ker wrote:
> Check all your speakers and the speaker leads. it sounds like one of
your
> speaker lines are grounding out. It's possible that the internal amp
on the
> unit has gone out, but in most cases when something like that
happens, it is
> a speaker grounding out. Sometimes it is just one of the speaker
terminals
> touching metel ot the head unit may have pinched a speaker lead when
the
> unit was installed and over time has rubbed through the wire.
>
> what year, make and model vehicle do you have. have you added
aftermarket
> speakers?
>
> --
> The Clown Prince of Car Stereo


I checked the 4 speakers leads and the wires back from the stereo with
a tester and they are ok (4.1 ~ 5.2 ohms). Also I *reset* the stereo
cutting the power from the battery, but it didn't work either. My car
is a Fiat Palio Sport 2005 with brand new Boss speakers (Riot RT-6CK
and RT-6930). BTW, this morning I have turned on the car stereo and
everything works fine :D. The audio back to normal in the 4
speakers.. My first thought about this was: the heat. Maybe Pioneer
has an overheat safety mechanism or something like that in order to
shut down the amps in overheat situations and then, when the amp is
cool again, the stereo back to normal. This is a guess, because I read
the owner manual, also I searched in the Pioneer's knowledge base and I
didn't find any information about it. The weird thing is last night,
after 4 hours since the audio problem started, the unit was cool and it
didn't work either, just after 14 hours the stereo back to normal. :/
The most important for my is the stereo unit is working now, but my
only concern is what if it happen again... :/

Dave

[joe.ker]

From what you just described it makes an even stronger case that a speaker
lead is grounding out.
if it happens again, take you ohm meter and test all the speaker leads to
ground. put one test lead to ground and use the other lead to the 8 speaker
wires. You should get no or infinite ohm reading. if you get any reading at
all then there is a short somewhere. I have seen some speaker voice coils
short internally to the frame, so that the speaker grounds out throught the
mounting screws.
most head units do have a thermal shutoff for overheating, but it usually
doesn't last very long (1/4 hr or less)

--
The Clown Prince of Car Stereo


> wrote in message
oups.com...
>
> joe.ker wrote:
> > Check all your speakers and the speaker leads. it sounds like one of
> your
> > speaker lines are grounding out. It's possible that the internal amp
> on the
> > unit has gone out, but in most cases when something like that
> happens, it is
> > a speaker grounding out. Sometimes it is just one of the speaker
> terminals
> > touching metel ot the head unit may have pinched a speaker lead when
> the
> > unit was installed and over time has rubbed through the wire.
> >
> > what year, make and model vehicle do you have. have you added
> aftermarket
> > speakers?
> >
> > --
> > The Clown Prince of Car Stereo
>
>
> I checked the 4 speakers leads and the wires back from the stereo with
> a tester and they are ok (4.1 ~ 5.2 ohms). Also I *reset* the stereo
> cutting the power from the battery, but it didn't work either. My car
> is a Fiat Palio Sport 2005 with brand new Boss speakers (Riot RT-6CK
> and RT-6930). BTW, this morning I have turned on the car stereo and
> everything works fine :D. The audio back to normal in the 4
> speakers.. My first thought about this was: the heat. Maybe Pioneer
> has an overheat safety mechanism or something like that in order to
> shut down the amps in overheat situations and then, when the amp is
> cool again, the stereo back to normal. This is a guess, because I read
> the owner manual, also I searched in the Pioneer's knowledge base and I
> didn't find any information about it. The weird thing is last night,
> after 4 hours since the audio problem started, the unit was cool and it
> didn't work either, just after 14 hours the stereo back to normal. :/
> The most important for my is the stereo unit is working now, but my
> only concern is what if it happen again... :/
>
> Dave
>

[Dave]

Hi,
Well, it happened again. The unit's sound died when I was changing a
CD :(. I'll try your suggestion and I'll test with the ohm meter all
the leads to ground. Also I think I'll test the stereo unit outside
the car, connect it to a 12v power supply and one speaker in order to
discard any problem with the wires inside the car.

Thanks for your help.

Dave


"joe.ker" > wrote in message news:<qWYYd.1667$UV2.1469@trnddc04>...
> From what you just described it makes an even stronger case that a speaker
> lead is grounding out.
> if it happens again, take you ohm meter and test all the speaker leads to
> ground. put one test lead to ground and use the other lead to the 8 speaker
> wires. You should get no or infinite ohm reading. if you get any reading at
> all then there is a short somewhere. I have seen some speaker voice coils
> short internally to the frame, so that the speaker grounds out throught the
> mounting screws.
> most head units do have a thermal shutoff for overheating, but it usually
> doesn't last very long (1/4 hr or less)
>
> --
> The Clown Prince of Car Stereo
>
>
> > wrote in message
> oups.com...
> >
> > joe.ker wrote:
> > > Check all your speakers and the speaker leads. it sounds like one of
> > your
> > > speaker lines are grounding out. It's possible that the internal amp
> > on the
> > > unit has gone out, but in most cases when something like that
> > happens, it is
> > > a speaker grounding out. Sometimes it is just one of the speaker
> > terminals
> > > touching metel ot the head unit may have pinched a speaker lead when
> > the
> > > unit was installed and over time has rubbed through the wire.
> > >
> > > what year, make and model vehicle do you have. have you added
> > aftermarket
> > > speakers?
> > >
> > > --
> > > The Clown Prince of Car Stereo
> >
> >
> > I checked the 4 speakers leads and the wires back from the stereo with
> > a tester and they are ok (4.1 ~ 5.2 ohms). Also I *reset* the stereo
> > cutting the power from the battery, but it didn't work either. My car
> > is a Fiat Palio Sport 2005 with brand new Boss speakers (Riot RT-6CK
> > and RT-6930). BTW, this morning I have turned on the car stereo and
> > everything works fine :D. The audio back to normal in the 4
> > speakers.. My first thought about this was: the heat. Maybe Pioneer
> > has an overheat safety mechanism or something like that in order to
> > shut down the amps in overheat situations and then, when the amp is
> > cool again, the stereo back to normal. This is a guess, because I read
> > the owner manual, also I searched in the Pioneer's knowledge base and I
> > didn't find any information about it. The weird thing is last night,
> > after 4 hours since the audio problem started, the unit was cool and it
> > didn't work either, just after 14 hours the stereo back to normal. :/
> > The most important for my is the stereo unit is working now, but my
> > only concern is what if it happen again... :/
> >
> > Dave
> >

[[email protected]]

Hi joe.ker,
You're absolutely right!!! :-) I tested every speaker lead with an ohm
meter and the front-right speaker had one wire to ground!! I don't know
how or where (or why I didn't notice before) the wire touch the metal,
but just for now I have connected the three speakers + sub to the head
unit (it sounds great!!)... Next weekend I'll check the right door to
find out where is the problem. Thanks man, you save my life!! It's
absolutely boring drive the car in silent. ;)

Dave

[joe.ker]

checks in the mail, right.....

--
The Clown Prince of Car Stereo


> wrote in message
ups.com...
> Hi joe.ker,
> You're absolutely right!!! :-) I tested every speaker lead with an ohm
> meter and the front-right speaker had one wire to ground!! I don't know
> how or where (or why I didn't notice before) the wire touch the metal,
> but just for now I have connected the three speakers + sub to the head
> unit (it sounds great!!)... Next weekend I'll check the right door to
> find out where is the problem. Thanks man, you save my life!! It's
> absolutely boring drive the car in silent. ;)
>
> Dave
>

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Yeah, you actually have to think of stuff.... Scary for me at least.

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;)