Monday, December 17, 2012

Basic electronics question from a young tech from BALTIMORE MARYLAND-USA

Hi Humphrey

I purchased DVD PLAYER REPAIR I am new to this how do you use OHM METER  to find a short  or check for short on a S.M.P.S circuit board


Hi Winston,
Thanks for buying my eBook and sorry for delay in coming back to you sir, regarding your question on testing for short you need to set your meter(digital meter) to diode test range and when you touch the two probes of your meter you should hear a beep(bell)

This is what you should expect when you have a short on a circuit or a component is shorted...some component are supposed to beep when tested this way when they are okay...a good example is the fuse...if the fuse is ok it should beep when tested on diode range test, also coils have low resistance and therefore you should expect a beep with them also.

With that little background let me answer your last to test for short on a S.M.P.S  board...shorting on the circuit board is usually caused by components which break down and short across the power line( this means component has one leg on the positive(+ve) line and the other pin on the ground...when this component short this means it creates a direct link between the live and the ground and therefore the circuit will fail to work and even cause the fuse to blow.

In S.M.P.S power supply the main component that short includes, main capacitor, diodes, control ic or transistor...Usually testing across the main capacitor two pins with your meter will tell if there is a sorted component or not...if there is no short across this line the meter will beep shortly and then the beep disappears as the main capacitor charges and increase the resistance.

For more info on this and much more i recommend  this book on basic electronics course book

Kind regards- Humphrey 

Author DVD player repair guide