Wall warts (ac/dc adapters) dieing

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Vegetarian by proxy
Dec 5, 2015
At the foot of the Black Hills
I posted earlier today about the power supply for my cable modem going tits up. (can I say that here?)

It's a 12v, 1.5A output - was kind of a lightweight one provided by NetGear.

I replaced it this morning with a heavy 12v, 1.2A model - I figured I could go with a little less oomph since I have the WiFi disabled on the modem.

Got home from work, wart #2 was dead.

They are plugged into the battery backup side of an APC UPS, so there should be a good surge protection.

Anyone got an idea why two adapters would crap out? Could the modem itself be the culprit? The modem is about 3 1/2 years old. NetGear CG3000D model.


Obscure Member
Apr 14, 2016
How old is the UPS? If the batteries in the UPS are on their way out it might do some funky stuff. It seems unlikely that two power supplies would die that quickly. Power supplies these days are made to take a variety of voltages and are pretty reliable. I would bet that it is just bad luck, but the only way to figure it out would be to eliminate variables. If you have a meter handy, I would check the voltage coming out of the UPS and go from there.


Alight With An Eternal Flame
Dec 4, 2015
I use these to protect my APC or Tripp Lite UPS units. They are good for being inexpensive, but their surge protection isn't as good as their marketing.

The difference is series-mode absorption of a surge into a big inductor vs. sacrificial MOVs.

When it matters, I use one of these in conjunction with one of the rackmount unit above:

The difference is dual-conversion on-line UPS vs. line interactive.

That said, wall wart power supplies are so cheaply made these days, it could have just been a bad day on the line in Hangzhou. Passes QC, but barely. It's weak enough that a relatively minor power event could take it out.

If you could see the fluctuations of the voltage and current on the grid, it would open your eyes as to how fragile it really is.