How to fix the stm32f4 discovery board?

[AUbar.1]

Hello,

Please help me on repairing my St board. Accidently, I gave 9V through the power pins of the board and with no smoke, no sparking, no blast, the board went off. RIP! Now, whenever I try to power on the board using the USB cable, this part (marked and shown in the image below) heats up and nothing works. Only that heats up no other parts.

Please help this poor little soul.

:(

Thanks in advance!

Aditya

[TDK]

U1 is the 3V regulator. It could be the only think you damaged, but it's hard to know for certain.

 

If you have the tools/skills, you could replace this chip with a new one.

If not, you could try supplying 3V directly which may work. However, the 5V rail is connected to a number of other things as well. In particular, it is supplied from the USB port, so you're not going to be able to use the USB ST-Link with that board, which will make it difficult to debug.

https://www.st.com/content/ccc/resource/technical/layouts_and_diagrams/schematic_pack/group1/0f/91/8b/39/b3/78/4d/c4/MB997-F407VGT6-B02_Schematic/files/MB997-F407VGT6-B02_Schematic.pdf/jcr:content/translations/en.MB997-F407VGT6-B02_Schematic.pdf

[AUbar.1]

Hey Tony,

Thanks for the reply. Actually I don't have a exact 3V power supply to power the board for which I ordered a multimeter to get a accurate voltage. Actually, the voltage regulator (LD3985M33R) that you are talking about and the protection diode (D1) is getting hot after powering the board. So should try replacing the diode and the voltage regulator? also please tell me if I can put a 7805/7815 voltage regulator there instead of the LD3985M33R.

Thanks in Advance!

Aditya