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How To Detect Short Circuit In ICs

By on July 8, 2013
How can I find a short on a scaler, microprocessor or microcontroller IC using my meter analogue or digital with the ohms scale? The reading will read infinite, 0 ohms or 200 ohms?


The short circuit many repairers are referring to is between the DC supply line to ground. Every circuit board should have at least one or more DC supply line and if one of these DC supply lines have a shorted component then the power supply or the mainboard will not function. In order to test it is easy, simply place your ohm meter (digital or analogues multimeter) test probes between the suspected DC supply line and cold ground. In fact you can place it in any DC supply line. The reading that you get should not have same reading and low ohm even when you switch the test probes. If you get one high ohm and one low ohm this is a normal reading and is good. If you get same reading even more than 200 Ohms then you should really take a look or inspect the DC supply line again. 

Another thing you need to know before taking any of the ohm test is that you need to know what type of circuit the DC supply is powering on. For example, in CRT Monitor the 6.3 DC supply line is going to the heater and back to ground so that the heater could light up. This means if you use your ohm meter to check on the 6.3 volt Dc supply line to ground you will get a very low ohm reading both ways (less than 0.5 Ohm). So you don’t think that the line has something shorted.  Practice makes you perfect so take out few different electronic equipment and test the output DC supply line so that in the future you could judge if a DC supply line really have problem or not (shorted).

If you have found the DC supply line indeed is shorted then simply remove the component along the trace one by one until the reading is back to normal. The last component (be it IC, capacitor, diode or etc) that you have removed (and the DC supply line no longer shorted ) is the one that have short circuit.


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