2Wire seems to have a problem with their DSL modems’ AC adapters failing, affecting models 1701, 2701 and similar models. Here I describe a failed modem AC adapter and the steps I followed to repair it. I include photographs of the AC adapter under repair and more information about cracking open the case and the capacitor required.
When a 2Wire 2701HG DSL modem AC adapter fails, the typical symptoms are 1) you can’t connect to the Internet with it, 2) the modem will not serve a connection to its administration page (http://192.168.1.254) and 3) the power light is steady red or blinking and the wireless light is steady green. Resetting the modem does not fix it. The modem will not go through the normal power up sequence when plugged in as described in the install guide available here.
A quick Internet search will reveal that this is a common problem and typically caused by the AC power adapter failing. This is a good page describing the problem and solution at fixya.com.
The typical reason that the AC adapter fails is because a single capacitor inside the adapter has failed. The failed capacitor is a 1000MFD 16V electrolytic capacitor. Failing capacitors are not an uncommon problem for electronics as I have previously discussed “Bad Capacitors – LCD monitor repaired.”
This failure can be fixed by buying a new modem, buying a new AC adapter or replacing the failed capacitor.
To save time and money I replaced the capacitor. You too can replace the capacitor with basic tools and soldering skills.
This saves money because ATT (or your DSL provider) will either recommend a new modem for $79 or if you request a new AC adapter, that will cost you $10 + tax with free 2 day shipping (overnight shipping is available for an additional $14.95) at the ATT website. You can also find replacement AC adapters at eBay, Radio Shack or electronics stores for a similar price.
The AC adapter required has an output of 5.1VDC 2A and looks like the following picture.
I repaired the AC adapter by replacing the failed capacitor.
To open the adapter, I used a putty knife and small hammer to loosen the seam holding the 2 halves together then I tapped around the entire seam with a screwdriver handle like I was opening a stuck lid on a jar. This was enough to separate the 2 halves.
I located the suspect capacitor – 1000MFD 16V and inspected it. Sure enough the top was bulging, a sign of a failed capacitor. The inside of the case also had a burnt electric smell.
I purchased a new capacitor for $1.19 + tax at my local friendly electronics store (Metro Electronics, Sacramento, California). Update 2016 – sadly Metro Electronics closed, I will miss the friendly local store.
A few notes on the capacitor: The required capacitor for this repair is a 1000MFD, 16V, 105 degree, electrolytic capacitor. If you can’t find a 16v one, you may substitute a higher voltage like a 25v and it should still fit OK in the case. Do not use a lower temperature rated capacitor. Note that the capacitor has polarity, the negative lead is marked with a stripe on the side of the capacitor. Observe the polarity when you replace it, in this case the negative lead goes in the circuit board hole further from the edge of the circuit board. You can find a replacement at an electronics store, Radio Shack or online, for example digikey.com.
I replaced the capacitor and glued the case back together with some plastic cement and tested it with the modem. It worked.
Good luck with your project!