Electroline EDA2500MMA

[rocky28965]

I accidently reversed the polarity on the power feed to this device.
Now it doesn't go.
Does that mean it's toast, or would there be some sort of safety device inside?

 

[Ubbe]

There's usually a polarity protection in those devices. Sometimes a diode in series, then nothing happens when using the wrong polarity, or a zener diode that protects both from wrong polarity and too high voltage by doing a short circuit and a fuse will blow. Open it up and look where the power goes and see if you can find a soldered in fuse. If you can see a bigger diode then measure that it only conducts in one direction and not totally a short circuit.

/Ubbe

 

[rocky28965]

Thanks.
The back seems to be sealed in place.
Looks like I'd need a can opener to get in.

 

[Ubbe]

I think I have a similar one called UG2802 that I where trying to get to its inside. Don't know if I managed that or what happened to it, it was maybe 10 years ago. Have you tried a hot air blower to see if the glue will loose its grip? Sometimes it's just silicon sealant to weather protect it.

/Ubbe

 

[rocky28965]

I managed to get the back removed and there is a definite smell of burning from within.
Had a good look around the power in port.
Nothing looked fried but there is one resistor missing a couple of stripes.
I removed the 10 screws holding the board in, thinking there may be some more evidence on the other side.
But it is firmly attached to the ports which look like they are bonded to the case.
So I bit the bullet & ordered another one from Amazon.

 

[Ubbe]

Nothing looked fried but there is one resistor missing a couple of stripes.
I removed the 10 screws holding the board in, thinking there may be some more evidence on the other side.

That resistor could be a coil that has blown open circuit from a short somewhere on the circuit board, or it is a voltage drop resistor for the internal voltage regulator.

I think I remember those screws and where also puzzled by how they got the circuit board installed and how to get it out.
That's probably why I archived that amp somewhere. It only cost me $2

/Ubbe