When we encounter the short-circuit issue happens on the common power supply unit, it would be very difficult to identity the root cause of short-circuit location since lots of the components connect electrically to this power supply so everyone of them do has the possibility to show the existence of short circuit.

If there is not too much components on the printed circuit board, use the test meter check every items one by one would ultimately find out the breakdown component or short-circuit point, if there is too much components on the printed circuit boards, the energy and time you have to spend on checking everyone one component could draw you out of mind and even though still has possibility that can’t find the short-circuit point if by bad luck. So hereby we would like to recommend a good method which can effectively increase the efficiency of the job:

First, you should have a adjustable power supply, the range of voltage is 0-30V, the range of current 0-3A, set OPEN CIRCUIT VOLTAGE same as the power supply voltage value of being repaired device, set the current value to minimum level, install this power supply onto the supply voltage point of the circuit board such as 5V end and 0V end of 74 series chips, increase the current value according to the level of short-circuit, touch the components by hand to feel its temperature, one of them who has obvious temperature increasing can be defined as problematic one, you can dissemble it from the circuit board to make further confirmation, during this process 2 points need to be ensure:

1 The operating power supply voltage shouldn’t exceed the operating voltage of original device;

2 The polarity of connected points on the power device by no means of reverse.

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