Hi, I got a PCB board which had a component failure due to an external short, the issue is that i am unable to identify what this component is (Blue Component in the picture RV 12), it doesn't have any code or text written on it. I have taken 2 pictures which shows the component and similar ones on the board which can be seen beside each relay.

http://pichost.org/images/2019/01/01/20190101_154337.jpg
http://pichost.org/images/2019/01/01/20190101_160707.jpg

Thanks in advance

 

RV typically refers to a Varistor:

https://en.wikipedia.org/wiki/Reference_designator

 

First, how do you know RV12 is the failure point? Second, you're not going to identify any of the charistercks of the device without a spec sheet, schematic and/or bill of materials (BOM).

I've worked in the field of Quality Control Electronics; and when checking the first article for conformance to the print and BOM, most resistors are not identifiable visually. For the most part it has to be taken on faith that the manufacturers set up their pick-n-place machine was properly loaded and that the components are correct. Usually testing will reveal if there is a problem. If a board does not pass test then a test tech will troubleshoot the board and identify the problem. A report is generated and all boards with that date code will be re-examined and possibly sent back to the manufacturer for warranty replacement. Whether the manufacturer repairs the boards or replaces them is their choice. But many times you can't identify a component because it's simply too small to put any markings on them. In other cases you may get a single letter or a combination of a few letters and/or numbers. As an inspector WITH a BOM I have to look up the manufacturer spec sheet and look for the designated marking on a part. Back in the days of macro electronics (through hole and wire/post construction) all parts were identifiable by color codes or numbers printed directly on the component. With parts being as small as they are - printing is often impractical. A user must assume on good faith that the components installed are correct. You can SPOT when a capacitor is installed in a resistor's location, but these tiny 3, 4 and 5 lead devices often have no printing on them whatsoever. Exactly what your RV12 is - without the BOM you're not going to know what it is or should be.

Which takes me back to my opening comment: How do you know RV12 is the failure point?