Netgear router clicking and dead

[kosta]

Hi, my Netgear WNDR4500 worked fine until I had it off for about 2 weeks. When I plugged it back in it didn't work anymore, there isn't even any lights flickering.
I changed the power supply, so that's not the problem.

Inside the router there is a regular clicking sound with about 1.3Hz. I believe it is coming from the round green component (I believe a self resetting fuse). I encircled it pink.


This part also gets really hot after 20s - I could smell something making me worried before opening. Can't see any damage, the big capacitors seem ok and hold some charge tested with a multimeter. Also the 2 flat fuses X250F right behind the power switch have continuity.

Any ideas what happened? I'm mostly curious and more than fixing it I'd like to know what is wrong and happened - so even "destructive" experiments would be ok.

[Monkeh]

Dead short on the input or output of one of the buck regulators. Maybe internal to the regulator.

[kosta]

I didn't know that was a "possible" failure mode for those regulators. Like the MP1484EN on this board. They can just short internally? By age or overheating or what? That would explain a spectacular failure of a self built DC-DC converter that worked fine for 3 years and suddenly burnt up.

So I could desolder the Nr. 2 pin (input) on all 3 MP1484ENs and power it back up, if it works push down one pin at a time and see if the fuse reacts? Or could I actually measure with just a multimeter without soldering?

[Monkeh]

Heat or overvoltage, especially the latter. Hotplugging the cable's a great way to blow up poorly designed switchers.

It's very likely if there's a short you can pick it up with an ohmmeter. You can also just see if any of them get hot. Other culprits include ceramic caps, the SoC, RAM, flash, or any other IC on the board. But the power stage is a good place to start.