Secret to modify a 110volt monitor to 230 volt

Have you come across this question where a customer asking you to modify a 110 volt monitor to 230 volt? Usually these customers brought back their monitors from oversea and want to use it in our country. By the way, Malaysia standard power line is 230v 50/60hz. The customers have only two choices either get a new autotransformer (step down transformer-from 220v to 110v) or get the monitor modified! Most of them prefer the latter one because it is cheaper and consume less space. The first choice though is quite straight forward, if the external transformer (step down transformer) placed near to the monitor it will cause the monitor to have some interference such as display shaking or the customers referred it as display swimming.

In order to successfully modify the monitor first you need to replace the power field effect transistor (fet) to a spec higher than the original one. The original fet came in many numbers but most of them have the voltage rating not exceeding 400volt. You may refer to your favorite transistor replacement guide for the fet specification. I'm recommending 2SK1118 or K1118 because it has a higher voltage and ampere rating which is 600 volt and 6 amp. The higher volt rating is to prevent the fet from damage due to peak voltage when the monitor is switch on.



The second thing that you need to do is to change the big filter capacitor from the original value of 220uf 250volt to 220uf 400volt. The higher voltage rating is to prevent the capacitor from exploding due to the increase of ac input which is 230v! If you measure the DC voltage after the bridge rectifier you will get around 300 plus DC voltage. So the 400v capacitor is capable to handle this problem. Here you have now the secret of converting the Ac 110 volt monitor to 230 Volt.