I have received several emails from my blog followers on how to go about with electronics items hit by power surges. Mostly they have a problem of getting a technician near them and others just want to try their hand in this fascinating career.
Therefore in this article I am going to discuss how you can handle this problem at the comfort of your house.
But first you need to be prepared to do some investment of the basic tool of the trade.
The minimum you should have include:-
These you can get them cheaply from your nearest electronics shop which I believe they are readily available.
After you have the tools now we are ready to start the job but before you open the equipment safety first.
First be very sure you have disconnected the machine from the power socket, I mean not just switching off the power via the power switch but removing the power cable completely from the socket.
I don’t advice you to do any voltage testing here unless you some basic training on safety precaution around the power supply in electronics equipment.
From my experience I have noticed that problems of power surge usually affect the primary power supply components, especially semiconductors and capacitors.
Failure mode of these components is either short or open so your meter should be set to low resistance range/diode test is even better here for short and high range over 20 K ohm for open.
Get a comfortable place/table and open the machine, keep note of how you open the equipment because when closing it up you would be doing exactly the opposite.
After opening the machine go straight to the power supply section, ie components between the inputs of the power supply and the main (switching) transformer.
First check the fuse with the meter on diode test- it should beep indicating the fuse is ok, if not consider the fuse gone.
Next measure the resistance of the surge limiter (white rectangular in shape) this too should read low ohms on the diode range.
Now if the fuse or the surge limiter is gone, DON’T REPLACE THEM.
Expect a big short ahead and the most likely culprit is the switching transistor or I.C usually the one you will find bolted to a heat sink. You can directly replace them without even measuring them.
There is also another small transistor near that big one, one can change it too, it is recommended because sometimes its goes and other times it can survive.
Continue Scanning the area looking for the main capacitor (biggish) rated 400volts for countries using 240 vac or 200 volt on countries using 110 VAC like USA.
If you find this main Capacitor has top silvery plate swollen, even a slight sign consider it bad. Also note if at the button of that capacitor there is some liquid oozing. If none of the above symptoms then consider the capacitor is ok for now.
From my experience changing those components always make the power supply to come up again.
If you don’t want to invest on the multimeter then you need to directly replace the components I have listed above: ie Main capacitor, chopper transistor, fuse, and surge limiter, diode/bridge are quite stable so you can leave them for now.
You can use this method to repair other electronics equipments using switch mode supply like DVDs, Monitors, etc so long as they have been hit by power surges.
Thanks you guys
Let meet in our next class