Can anyone help me identify this component? It just says 0 or D on it (I think it's a zero). I tested it for conductivity with a multimeter – doesn't seem to have any (tried both polarities in case it's a diode). Tested for resistance: nothing (i.e. infinite resistance), although I'm not 100% sure I was touching the contact points correctly, so don't take this as an ultimate measurement. Thanks in advance!
Electronic – How to identify this component? It just says 0 on it
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Related Solutions
This is a Hongzhi Enterprises (HEL) brand metal-oxide varistor.
The website doesn't mention pending safety approvals, but this part has both UL Recognized component and (what looks like) CSA marks on it. It's not surprising that the website is a little out of date, I've seen it quite often with offshore smaller suppliers.
I've never used this brand of part, so I cannot speak for its robustness.
Specs:
I agree with others that this is most likely intended as a transient clamp meant to suppress the inductive kickback of a de-energized relay coil.
The part is connected to pin 5 of the USB connector, which is the 5V supply from USB. It is most likely to be a fuse: either a PTC resetable fuse or a non-resettable fuse. Its marking are consistent with a SMT fuse, although to understand the marking you would need to know the manufacturer of the fuse. It is unlikely to be an inductor or ferrite bead, since those parts are usually unmarked.
After the fuse is a diode of some sort connected between the 5V supply and Ground. This is probably a TVS diode to protect the device against voltage transients.
If you follow the PCB trace it then passes through part which is probably a ferrite bead which is used to reduce EMI emissions. SMT ferrite beads are usually unmarked.
Best Answer
This is a 0 Ohm resistor. Probably in 0805 package.
If the multimeter shows infinity (open circuit), or any significant resistance > 0, when measuring the element's resistance it means that it is damaged. The multimeter should show zero resistance when measuring such "resistor".
On the PCB you can replace it with a solder blob or a piece of wire.