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I'm helping a friend by attempting to repair this display PCB. It uses 24vac input and he accidentally hooked it up to 120vac.

I am trying to identify the two components in this picture under the burn marks. I'm pretty sure they are diodes but am looking for more specifics so that I can order replacements. Anyone able to direct me anywhere or know anything about the two components labeled MX 21A.

enter image description here

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    \$\begingroup\$ My guess is way more then those are damaged if you hooked it into 120v \$\endgroup\$ – MadHatter Dec 28 '18 at 19:09
  • \$\begingroup\$ These were my thoughts exactly...but I told my friend I would try replacing those and see what happens. \$\endgroup\$ – stevo Dec 28 '18 at 19:14
  • \$\begingroup\$ There's several small traces running in between those diodes that got vaporized. The burnt spot might also have become partly conductive and need cutting a gap. If it's a multilayer board that'll get messy quick. \$\endgroup\$ – Unimportant Dec 28 '18 at 19:53
  • \$\begingroup\$ Thanks for the heads up, I'l look out for this and check it out with my multimeter \$\endgroup\$ – stevo Jan 4 '19 at 3:14
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MX is an SMD Code for TI's TVS protection diode that may withstand 48V

SMBJ48A The left side, DS1 vaporized some material.

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