I have a modem whose power adapter shows input voltage as 100V to 240V. In my place, we get 220V as a power supply in which it works okay. But when the power goes out and the inverter starts working then it does not work properly. The power light in the adapter keeps blinking and also the light in modem which shows the power supply keeps blinking. I checked the voltage in my socket and it was around 241V. So I think that because the voltage from the inverter is a little high so maybe the power adapter is not working properly. So maybe if I can reduce the input voltage to the adapter by a little then it will work properly. So I want little help on how to decrease the voltage by around 20 volts to bring the input voltage to around 220V.

I am a software engineer by profession but I have worked on embedded devices so adding some resistance came to my mind but I have done that when I worked with 5V or 9V battery. Also, I won't be comfortable using a transformer to decrease the voltage. So could anyone tell me if it even possible or not and if yes then how?

Thanks in advance.

 

But when the power goes out and the inverter starts working then it does not work properly.

Is your inverter a sine wave type?

 

Welcome to AAC!

The power light in the adapter keeps blinking and also the light in modem which shows the power supply keeps blinking. I checked the voltage in my socket and it was around 241V. So I think that because the voltage from the inverter is a little high so maybe the power adapter is not working properly.

Fiddling around with line voltage isn't for inexperienced people. I'd just look for an adapter that works better with your UPS.

A safer way to test your hypothesis is to get a 2:1 step down transformer and reduce the voltage to the adapter to its lower range. Another option is to use an autotransformer (generically called Variacs, which is a brand). People who have them probably already know that most of them don't provide line isolation and that failure can be even more hazardous.

FWIW, the only devices I've had that cared about dirty power were UPS's. Had one (APC) that alarmed constantly when I was powering my house with a generator.

 

I checked the voltage in my socket and it was around 241V. So I think that because the voltage from the inverter is a little high so maybe the power adapter is not working properly.

Inverter? Just a thought, but you might consider running the modem off of whatever is powering your inverter. Bypass the inverter and adapter. Of course the details matter, particularly voltage, but it's something to consider.