AR 112PS

xjghost

So a friend gave this sub to me several years ago. It quit working for some reason. I decided to dig in a see what I could find. Is there any way to get the wire schematic and see if I can figure out what is going on? My Google skills aren’t that good. So far I’ve found ver little. I uploaded two images. Is that what a leaky cap looks like?

Clipdat

That's either a leaky cap or that black goo stuff that a lot of Chinese manufacturers use to "secure caps" on boards like this. That black adhesive tends to **** the bed after several years and tests have shown that it actually becomes conductive and can interfere with the proper functionality of the adjacent caps, etc.

It's a common problem in KRK's older powered monitors, so there's several tutorials available online for addressing it, if it turns out that is the case.

It's hard for me to tell if this area of the PCB is discolored due to heat damage or stained by the noxious black goo:

xjghost

Thanks for the response. I'll try and get a better picture and see if it is some sort of goo.

VR3

Yeah hard to tell, looks similar to this goo

mhardy6647

Looks like aged adhesive as opposed to bad capacitor to me, FWIW.
That said.
1. If 'bad' electrolytic capacitors manifest any visual indication, it is usually a bulging case. Electrolytic capacitors can fail catastrophically; they have an "x" shaped vent cut into the top (axial lead caps) which should "pop" if they do. Electrolytics can explode rather dramatically, but will usually only do so if connected 'backwards' in a circuit (which, of course, is not the case here).
2. That adhesive is purported on the internet to become electrically conductive when it gets old and hard and dark-colored. I am skeptical, but that's what the internet says.
3. The term "leaky" is applied to capacitors -- but it doesn't usually mean physically leaky, but rather electrically leaky.

I hope some of the twaddle above is useful to the OP.

xjghost

Very helpful. I’d like to learn more about this. When I get a chance I’ll continue looking for more info and schematic on this thing. I know it has power to the transformer. When I open it back up I’ll get better pictures.