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My Hikvision door station got shocked during a storm. I can see that a couple of SMD components got burnt and turned black after that. There's a bunch of components on the board and all of them seem to be marked with "2039 CP" marking. They're close to a slot which provides voltage for electromagnet that releases the door lock.

Burnt components

As far as I researched it's a bi-directional TVS diode (hence the CP marking), but I don't know if I'm right and if buying a component like SMBJ36CA would fix the problem with the board not working.

What is the component? How to pick a right replacement?

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    \$\begingroup\$ The lack of polarity marking on the component is peculiar. Very likely it's just some manner of Schottky rectifier diode placed in series with the relay contacts, that can handle the current. Or maybe acting as freewheel. They won't like a lightning event with high voltage in reverse. If you measure forward voltage on an intact one when the board is unpowered, you should have some 0.2V - 0.4V and then it's a Schottky. Anything that can handle the current will do, the package is called DO-214AA-2 "SMB". \$\endgroup\$
    – Lundin
    Commented Sep 20 at 10:35
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    \$\begingroup\$ I wouldn't rule out that the relay contacts are damaged as well though, so changing the relays as well would be wise. \$\endgroup\$
    – Lundin
    Commented Sep 20 at 10:36
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    \$\begingroup\$ The lack of polarity bothers me as well, but I can clearly see a "+" marking on the board next to each of the components. So most likely it HAS polarity but it's not marked \$\endgroup\$
    – Maskey
    Commented Sep 20 at 14:55

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I think you found yourself, looks like SMBJ36CA bi-directionnal TVS diodes (marking "CP") close to the header to protect both side circuits. The marking looks generic and shared by several Chinese brands (lot/date code then "CP"). So you will easily find a replacement, it is a generic part number.

image link (lcsc):

enter image description here

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