Fried speaker crossover

[egan.]

Hey Guys. So I inherited a couple of electrostatic speakers and it turns out the crossover is fried. Being electrostatics things are a little more complex than usual.

(click for a bigger pic).

So those of you that know more than I do, do you think I can get away with just replacing the fried resistors? Any advice would be much appreciated.

 

[amarshism]

Damn they fried good

 

[Terminus]

Looks like it may have fried another small resistor on the PCB, and maybe that little IC chip right next to it. Hard to tell with the blur. Could probably be fixed if you could read the model number and knew the values of the resistors.

 

[egan.]

Sorry for the quick phone pics. Maybe this will be a little more helpful:
http://people.duke.edu/~eto2/temp/IMG_0738.jpg
http://people.duke.edu/~eto2/temp/IMG_0739.jpg
http://people.duke.edu/~eto2/temp/SL3powersupply120V.pdf
http://people.duke.edu/~eto2/temp/sl3 crossover schematic.PDF
The crossover resistors are 20w/3ohm but I've no idea on the pcb I fear I'll end up sending them back to martin-logan.

 

[JakeAC5253]

I wouldn't be worried about the components myself, those can likely be replaced without much trouble. What I see as the bigger issue is the board damage the flare up has caused. All those traces that now are covered in ash and carbon deposit that will have to be cut and bridged around the burnt areas, and that's just on the surface. If this is a four layer PCB (hard to determine from this angle) the board could have warped and severed internal connections. The fact that we have 3Ω, 20w resistors which caught fire tells me this circuit could be dangerous, so I would refer it to someone who knows what they are doing.

 

[egan.]

Fair enough. I'll likely take it to my local guy before I send the back to ML. This is one of those things where something cool and free is rapidly becoming less free.

 

[TheWinterSnow]

It looks lilke for the most part that the 3 ohm resistors caught fire and just left carbon on the board. You will have to clean the carbon off the board to see the extent of the damage. I do think that the board may be unaffected, but if any of the components are damaged in the area you would have to be careful desoldering the old parts and soldering the new parts. Some of the traces look like they may be ready to separate from the board, and if that is the case you could have to be careful to make sure they don't separate and if they do, trace repair needs to be done. Some trace repair may be needed regardless. Again you would have to look at the traces when they are cleaned in order to really know that.

As for trace repair, having experience doing it myself it is not easy and shouldn't be done by someone who isn't an expert in soldering and doesn't have the proper tools. I don't think that the board has more than two layers so mostly some component replacement and maybe some trace repair is needed. I still can't recommend repairing it yourself if you are not very skilled in electronics.

 

[egan.]

Yeah, I'm good for the basics but my PCB experience is limited. I'll follow up with my local guy and ML's tech support. Thanks for the rapid responses guys.