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What are these gray conponents? What do the letters/numbers represent? How can I properly read them? How can I tell if those gray components are bad?

The board is a UDOO Volt v8, that constantly reboots before really starting up. I used a thermal camera and saw that the gray components were the hottest components on the board. I'm wondering what are they exactly, so that I can order some replacements off of Mouser or DigiKey.

enter image description here

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    \$\begingroup\$ How hot were they getting (thermal cam should have given you a value)? Hot is subjective and could be normal. \$\endgroup\$
    – Tom Carpenter
    Commented Oct 10 at 19:41

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Those components have designator L on the PCB silk screen, so they are inductors. They also look like inductors.

The marking R15H most likely means they are 0.15 μH or 150 nH.

All other parameters and markings are unknown and manufacturer specific, so the inductor parameters can't be known.

Also, they generally do not break, so if they heat up, it just means there is current passing through them like there should be. If they heat up abnormally, then it means the inductors of the power supply are fine and something downstream of the inductors is broken or short-circuiting.

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  • \$\begingroup\$ The inductor might be a KEMET MPCH0740LR15. The markings look very similar, but hard to say without knowing the size. \$\endgroup\$
    – nanash1
    Commented Oct 10 at 16:31
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They are inductors as per the “L” designators on the left. To read the part number you should open a datasheet and see what each segment of the part number means. To find this exact part more information is required. There are many ways they can be damaged. One of them is if too much current is passed through them they can behave as an open circuit. Therefore, a continuity check between terminals could be a good test (part removed from PCB).

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    \$\begingroup\$ It's unlikely they are all bad so if they show roughly the same temperature, it's probably a red (hot) herring. \$\endgroup\$
    – pipe
    Commented Oct 10 at 14:32
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    \$\begingroup\$ If they all heat up it means all of them pass current and are not broken. You also cannot test continuity in-circuit, you would have to remove the inductor from the circuit to test it. Also nice idea to open the data sheet to know which component it is, but impossible to know what component it is to find the data sheet for it. \$\endgroup\$
    – Justme
    Commented Oct 10 at 14:37
  • \$\begingroup\$ @Justme Yes, I should be more precise (hence edit) and highlight that the suspected component must be removed from the PCB. \$\endgroup\$
    – Wintermute
    Commented Oct 10 at 14:41

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