# Help on ID for SMD component (probably diode)

I recently smoked a DC motor control board and need help identifying the wounded component.

before picture (H2 and sideways 3)

and here it is, wounded

It looks to me like a resistor SMD; but, of what type/value?

Thanks and regards

• I'm sorry for your loss. There's nothing we can do. That component has passed its last electrons. To be fair, it looks like it passed a lot of them during the last seconds of its life. No, it's not a resistor, it's either a diode or a tantalum capacitor. – pipe Aug 6 '16 at 15:29
• From the picture...a diode. – Robert Endl Aug 6 '16 at 15:31
• Maybe a BZX585-C6V8 6.8V zener diode? Ask your favorite search engine for "smd marking h2". – starblue Aug 6 '16 at 15:41
• @starblue I don't think a 6.8 volt zener on a 12 volt rail is such a good idea, though on the other hand, maybe that's why it's now pitch black and the PCB is covered in soot. :) – pipe Aug 6 '16 at 15:50
• It is connected to 12V with the right polarity, it is in parallel to a capacitor, and the other end goes to a via (not to ground I suppose, rather a series resistor). The OP seems to have a second working circuit, so he could check and for example measure voltages. – starblue Aug 6 '16 at 15:54

Judging from the location on the board and the marking H2, it's a Zener diode, to protect the 12 volt rail from overvoltage. The value would be something a little above 12 volts.

I'm not quite sure about the package. Maybe SOD-323 or SOD-523.

Looks like it is a 12V zener diode.

http://www.diodes.com/_files/datasheets/ds31038.pdf

The linked document gives codes for various zener diodes from Diodes Incorporated.

Yes, there seems to be a stripe at the left side of picture 1 indicating a diode.

You could remove it to test the rest of the board. It would be best to test with a load consisting of LEDs or a small 12 V lamp as these would not give an inductive kick on switch-off (which the diode may have been there to absorb / shunt).

If that works you could replace the dead diode with a regular through hole type - if that's all you've got. If the pads are damaged beyond use then piggy-back onto the adjacent component. Others are suggesting that the component is a zener diode. Without seeing more of the circuit I couldn't comment on the configuration.