So I've accidentally knocked down a computer system used to take kitchen measurements. I've caused a short in the power supply which caused two SMD components to burn in the motherboard. I've identified one SMD, but I'm trying to figure out what the other components is. I have identified several other SMD that match the one that burnt, but I can't figure out what it is. It has three pins and the one that burnt is close to a 12V power connection. The top surface of the SMD has the number 301 on the left side and two dots top center on the SMD. I've also noticed that under the damaged component it has the letter D followed by a number. I want to believe it is a Diode, but I'm not sure or what type. I've attached some pictures of the component that I'm trying to determine what it is so i can buy it and replace the burnt one in hopes to salvage this system. This system is too old and the manufacturer no longer makes the board. I've asked for a schematic and component list and they can't provide it. Buying another one can cost between 15K to 30K. I'd like to try and see if I can replace the damaged component before I buy another one. Any help will truly be appreciated. Thank you!

smd burnt

smd burnt notes

overall view


1 Answer 1


Yes, the D identifier underneaths means its some type of diode.

If it was the same as the 301 one below it then maybe it is this one:

FDV301N, SOT23 n-ch 'digital' fet 25V 0.22A


  • \$\begingroup\$ Wow, thank you for the response. This surely looks like a possible match. I guess one way to find out if it's the one is to buy it. If there are any other possible matches I'd love to hear it. Thanks! \$\endgroup\$ Commented Jun 1, 2020 at 3:08
  • \$\begingroup\$ that looks like a Q \$\endgroup\$
    – jsotola
    Commented Jun 1, 2020 at 3:16
  • \$\begingroup\$ @jsotola Q4 could be the DNP's designator. Because there's nothing written next to it. \$\endgroup\$ Commented Jun 1, 2020 at 4:00
  • \$\begingroup\$ @carloscarbajal try to clean the burnt area and read what's written (i.e. D or Q). \$\endgroup\$ Commented Jun 1, 2020 at 4:04
  • \$\begingroup\$ my bad .. that is the identifier for the missing component ... you will have to remove the burnt component to see what is written under it \$\endgroup\$
    – jsotola
    Commented Jun 1, 2020 at 4:29

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