Linksys E3000 blinking Power LED

July 23, 2016

 

I recently scored a Linksys E3000 wireless router during a recent trip to a Goodwill store. I was so excited and it only cost me two dollars. When I got home to test it out my excitement quickly turned to frustration. The power LED constantly blinked and the other lights would lit up every now and then as if the router was on a resetting loop. After several minutes of this the power LED finally stayed on and I was able to communicate with it using my computer. I attempted to update the firmware, thinking it may have been corrupted, when the power LED began blinking once again and the update failed.

I searched online and found numerous posts about this same problem. People associated the problem to an over-heating issue. Although, the router does warm up quite a bit, my particular problem starts even when the unit is cold and appeared to improve once warmed up. I think the blinking power LED is a general fault indicator.

A firmware update finally succeeded after numerous failed attempts. Thankfully, I didn't brick the router in the process. Unfortunately, the router still would not work properly. I surmised a hardware failure due to heat fatigue. There are two areas on the board that get extremely hot to touch. I was pretty dejected at this point when I came across a post from a user that suggested inspecting the electrolytic capacitors. On my unit, the capacitors physically looked good. No leaking or bulging whatsoever so it didn't even cross my mind. I have a capacitor tester handy so I decided to pull all the electrolytic capacitors and test them out of circuit.

Looking at the board there are several voltages printed on board. The power adapter supplies twelve volts to the router and the router in turn down converts the voltage to supply power to the different components on the board. There are seven electrolytic capacitors on the board: 4 x 470uF 10V, 2 x 100uF 10V, 1 x 2800uF 25V.

Linksys E3000 boardLinksys E3000 board

In my particular case, the 470uF capacitor, which is part of the 1.284V circuit was the culprit. I tested this one first due to the proximity to the heatsink, which gets very hot. My ESR meter read 329.5uF, which is thirty percent off spec. The dissipation factor measured 1.379 and the series resistance was 5.6 ohms. A comparably good capacitor would have a dissipation factor of 0.01 and series resistance of 0.2 ohm. I replaced this capacitor and the router was good as new again.

Linksys E3000 capacitorLinksys E3000 bad capacitor

An ESR meter is a handy tool to have when dealing with capacitors. The Uni-T UT612 ESR meter is a decent device but buggy at times that it shuts off randomly. When it works it's a great tool for times like these.

I replaced the rest of the capacitors even though they didn't measure too badly, but certainly nearing the threshold of being rejected. The capacitor brands are Capxon and Suscon so they weren't top shelf capacitors to begin with. The replacement capacitors I used are physically larger than the originals so I had to tweak their position for clearance once the cover is put back on.

Also, the antennas are plastic welded to the base. I simply took pliers and pinched the welds off with not much effort. When it came time to reassemble I used my soldering iron to remelt the plastic welds to secure the antennas as they were.

The Linksys E3000 has three antennas for the 2.4 GHz frequency and another three for the 5 GHz frequency. What's odd is two pairs are physically connected together. It baffles me how it works.

Linksys E3000 bad capacitorLinksys E3000 bad capacitor

This router is probably one of the toughest to crack open. Checkout my other tutorial on how to open it up and save yourself the frustration.

This was a very satisfying project. I bought a two dollar broken router and got it running again. I'm glad I found the post suggesting inspecting the capacitors. Otherwise, I would have just returned the router to Goodwill and missed out.

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