busted Behringer B1200D

[silverneedles]

my Behringer 1200D subwoofer started acting up after a few months (wouldnt make sound after turning on for 10-15 min),
but now it completely appears dead - no lights or sound on power-on.
I opened up the amp but i dont see any bulging or leaking spots. i unplugged the filter board but that didnt do anything. ... i dont know what to do next ... i have a basic multimeter and can do some basic soldering :P

[killa]

I assume you checked fuses?

[Psycoacoustics]

I assume you checked fuses?

You would think that all of us here would always do that FIRST! However,,,,,,,,

I’ve been the idiot that needed someone to tell me that!

Thanks Killa,,,,,, we all need to be reminded from time to time. Mark

[Millstonemike]

Picture of the board (hi-res).

[silverneedles]

i found the fuse and its continuous
the power plug and wires to board look fine
the main board (with the transformer? yellow thing) - pictures 1,3,4
the eq/in-out board is the 2nd picture

[Psycoacoustics]

In the first pic, the two brown colored resistors. Is that one lead insulated or burnt?

[Millstonemike]

In the first pic, the two brown colored resistors. Is that one lead insulated or burnt?

Insulated. You can see it when the pic is full size and other components here and there.

[Millstonemike]

If you have a multimeter ... my next step would be to measure the DC voltage out of the switching power supply. It looks like you could measure that at J1 (+) and the trace to the right leading under the third cap next to the 100V 110V sticker (DC gnd) . You have to insure that you get a good connection to the trace through any solder mask on the PCB. YOu should see somewhere in the neighborhood of 50 V to 80 V DC out of the PS.

[silverneedles]

ok got 70V

[Millstonemike]

ok got 70V

I can't find a schematic for this sub, so we're flying blind here. In the attached pic, what's the "goop" circled and is it coming from something else. Also, can you read a part number on the large black component with goop at both ends.

[silverneedles]

the goop is some kind of resin they also put on other screws
the black thing was just plastic covering the metal part, this was just to hold down the board...
i unscrewed everything and flipped the board... still dont see anything suspicious

[wogg]

Looks like that's some sort of switching IC, the plastic piece was likely to ensure a good bond to the heatsink on the other side. The goop is typical in manufacturing, glyptol or other enamel used as a thread lock.

Agree with Mike... flying blind. All we know now is you have 70V of DC power but nothing out of the amp...

[silverneedles]

so then i could just get an inuke w/ DSP (correctly matching ohms and watts and stuff) and just basically hook it up to the driver itself

[Millstonemike]

so then i could just get an inuke w/ DSP (correctly matching ohms and watts and stuff) and just basically hook it up to the driver itself

Quite possibly. You would have to seal up the box. I'd think it through for a while. Whether the separate components suit your needs and possible upgrade paths versus a new self contained sub.