Voltage collapsing when leads are connected to amp

[djlostcause]

I have an Alpine mrp-m450.
I removed it and reinstalled it in order to paint my speaker box.
Upon hooking it back up, the power light came on for a few seconds and went off.
I have tested the power, ground, and remote leads when disconnected from the amp.
They are all operating properly.

However,...
when I connect them to the amp,
the power lead drops to around 6-7 volts
which leads to the amp not working.

I have taken the amp apart and not noticed any burnt transistors.

Anyone have any ideas?

Thanks ahead of time.
I will post more info and updates asap.

-josh

[Perry Babin]

The problem is in the wiring in the vehicle. If the amp was drawing enough current to drag the voltage to 6v, the fuse would have blown in the B+ line feeding the amp. I'm assuming that the vehicle's battery is in good condition and able to start the vehicle.

[poopydoopynoopy]

Originally Posted by Perry Babin

The problem is in the wiring in the vehicle. If the amp was drawing enough current to drag the voltage to 6v, the fuse would have blown in the B+ line feeding the amp. I'm assuming that the vehicle's battery is in good condition and able to start the vehicle.

Yup.
I'll go further and wager its a ground issue...

[djlostcause]

The amps power wire is connected directly to the battery and has an inline fuse.
The ground is connected to the trunk metal via a bolt.
The wiring was not changed as I only removed and reinstalled the amp.
The amp worked fine before.
...
I went out side to double check as I was typing this....
The amp is now turning on and voltage is fine.
(strange because no change since last time i checked)

But now....
there is absolutely no output (audio input is good).
(May have accidentally touched wires in the past 2 days of testing)

Still no sign of burnt transistors.
The amp is open and connected.
Any particulars I should check ?
Any help greatly appreciated!

[djlostcause]

Double checked a second ago...
wiggled the ground.

Amp is now turning on and voltages are correct.

But now...
there is NO output whatsoever (audio input is good).
(May have touched/crossed wires in the past 2 days of tryin to figure this out)

The amp is opened and connected.
Still no sign of burnt transistors.
Fuses are still all good.
Any particulars I should check?
Any help greatly appreciated.

I am no stranger to soldering on pcbs and components.
If only I could figure out which components need to be replace.

[Perry Babin]

How did you confirm that the signal line feeding the amp had audio?

[tsmith1315]

Check your speaker leads, too.

[djlostcause]

[IMG]file:///C:/Users/JOSHSA%7E1/AppData/Local/Temp/moz-screenshot.png[/IMG][IMG]file:///C:/Users/JOSHSA%7E1/AppData/Local/Temp/moz-screenshot-1.png[/IMG][IMG]file:///C:/Users/JOSHSA%7E1/AppData/Local/Temp/moz-screenshot-2.png[/IMG][IMG]file:///C:/Users/JOSHSA%7E1/AppData/Local/Temp/moz-screenshot-3.png[/IMG]none on the transistors are proving to be shorted

but some of my transistors (IRFZ44N) on the output side are reading >1 volt

http://www.bcae1.com/images/gifs/trnchk04.gif

is this normal?

[djlostcause]

is a voltage regulator essentially a transistor

[Perry Babin]

Many voltage regulators use transistors but not all.

Reading >1v? How was that measured?