I wanted to use an old Netgear WGR614 router that I had lying around, but when plugged in it started to make a howling noise.
Luckily I’ve seen this before. Netgear used a batch of bad capacitors in these a few years ago. Sure enough, when opened, that capacitor was bulging. A trip to Radio Shack (I had some capacitors the right value, or close enough, but they were too large to fit inside) and $1.50 and some soldering later, and the router is working again.
I installed about 4 of these routers a few years ago, and I think all of them failed within less than 2 years with this problem. Replacing the capacitor fixed the problem each time and I haven’t had any of them die since then.
The real problem is that the ground side is a thermal plane, it’s hooked on both sides of the board to a large copper plane and it’s almost impossible to get the hole unsoldered cleanly, at least with my tools. It took about 30 or 40 tries with a solder sucking iron. I probably could have just tacked it onto the surface but the pad was tiny and I’m sure it would have just failed again later.
Note even this capacitor is a bit large and I had to lie it on its side, but that’s OK. I’ll put some silicone under it to keep it from vibrating and cracking the leads as well.