using 12V power adapter on a 9V wifi modem?!

Thread Starter


Joined Dec 28, 2015
I used an 12V adapter for my modem(philips SNB5600) instead of 9 volt.
It was working but just after 10 seconds it made a noise and It didn't work anymore.
So I want to ask,what exactly happened and is there any hope to fix it and how can I repair it?


Joined Apr 5, 2008

You will have burnt someting inside the modem.
It was rated for 9 Volts and you applied 12 Volts, so over voltage might lead to over current and burning stuff.


Roderick Young

Joined Feb 22, 2015
If you have a multimeter, check the voltage on the 12V adapter. Is it really 12 volts? Maybe it was an old unregulated type, and due to the light load, had a much higher voltage.

As to what happened, was the sound like something popping? What did it sound like? Was there a smell, especially a burning smell? Open the modem, looking especially for burned components or bulging / leaking capacitors. Post a picture here, if you can. The most reliable thing to do would be to simply get a new modem rather than trust one that has been exposed to overvoltage, but I'm assuming you're interested in what happened.


Joined Sep 17, 2013
Any resistive component receiving 12V instead of 9V would generate 78% more heat than it was designed to! Not surprising if something fried :(.


Joined Mar 30, 2015
So I want to ask,what exactly happened and is there any hope to fix it and how can I repair it?
No one can tell you exactly what happened or how to repair it.

Chalk it up to experience. Buy a new one and pay more attention to details in the future.

ian field

Joined Oct 27, 2012
The adapters may also have had different polarities - zap!
Wouldn't have worked for a while if that happened.

Most modems I've ripped for parts, had at least 3 SMPS regulators for on board rails - some are buck with series control transistor/MOSFET, if they fail short circuit; the unregulated juice hits the logic supply rails and its game over.