I started writing about repairing laptop motherboard and about repairing radios like ubquiti radio antenna. I wrote note about general guidelines to check electronics components, how to test MOSFETs on motherboards PCB, how to find short circuit quickly by testing inductors. Here I wanted to write note on SMD(Surface Mount Device) capacitor. The.SMD capacitor are the most abundant components in any PC or laptop motherboard. They are all around power supply circuit, around integrated circuits and come in various sizes. The following picture shows SMD capacitor with various sizes.
To check whether SMD capacitor is shorted or not we can use the continuity mode in multimeter. Place the two probes to each side of the capacitor, if the capacitor is good then there will be reading on the multimeter and if it is damaged then there will be continuity beep indicating the capacitor is shorted. In the earlier note on how to check short circuit quickly on motherboard we checked the inductor w.r.t ground. If such short circuited capacitors are found, they should be replaced with the same size and color of the capacitor. Because two SMD capacitor can have same size but the color can be different.
One thing to note is the exception rule to the chipset capacitors like CPU, graphics card, north bridge IC.These chipset capacitors are found on the back of the IC. If you check these capacitors with continuity mode then you will hear continuity beep always if the chipset is not removed. If you could remove the chipset like CPU and check its capacitors underneath the chip on PCB then you will not hear the continuity beep. That is because they provide so low resistance across it that it is like short circuit. But capacitors other than the chipset circuit capacitors should how normal reading as shown in the picture below.
If the SMD capacitor is shorted then you should hear a beep and reading of 0.0 as shown in the picture below.
So here in this note I wrote about how to check or test SMD capacitor and what one needs to aware of.
