evilm

The other ic, ALTJ 261, I mentioned could be damaged, and also could be the one responsible by the 5VDC rail, indeed is a 5V regulator. It is manufactured by mps(Monolithic Power Systems). The code for this component is: NB679GD (Model in QFN-12 package) The datasheet for this component can be found here: https://www.monolithicpower.com/en/documentview/productdocument/index/version/2/document_type/Datasheet/lang/en/sku/NB679/document_id/4030 You can check the marking references on mps parts here: https://cdn.badcaps-static.com/pdfs/6821fb00412750dfe538563299cc5945.pdf and here: https://www.badcaps.net/forum/troubleshooting-hardware-devices-and-electronics-theory/troubleshooting-laptops-tablets-and-mobile-devices/80630-ic-marking-codes-and-datasheets#post1482820 I'm sharing this, although it doesn't mean that this ic is damaged, you need to test it to see if it is giving the correct output of 5VDC, and check for any shorts on the board. The input range for this regulator varies from 5.5VDC to 28VDC. So maybe it did not got damaged by the over voltage from the 24VDC power supply. Maybe the diode protected the other components as well. As I stated earlier, you should test for short circuits in the power rails. Test if there is any shorts between 12VDC to GND, 5VDC to GND, and 12VDC to 5VDC. Maybe only the diode is faulty on the board. It's also possible that the main sata ic got damaged or some smd capacitors got shorted. Sometimes is just a short on the power rails that causes a board to malfunction or to not function at all and, apart from times when more things got damaged, usually fixing the short or the faulty components on the power rail puts everything to work again. I don't know if you are used to work with electronics, if not I advise you to contact someone that can help you. Maybe indeed it is an easy fix, maybe only the diode is faulty but working with smd components sometimes can be tricky. I guess that with all this info, if the problem relies in fact on the power rails, anyone skilled with basic smd soldering and electronics knowledge could replace the diode and maybe some other faulty component along the way while performing tests for any shorts on the board.

I'll take a look upon this tomorrow. For the diode, the side with stripes is the cathode. By the looks on the photo, it doesn't seems that the other component (the one with 12 pins) is damaged. It looked bad on the first photo you attached to the post. Although I cannot say for sure, it may be damaged, even if it doesn't show any external markings or signs of damage. In many cases damages like this one, that happened by over voltage, end up in something like just a shorted diode, it all depends on the board design and components used. You can replace this smd diode with any other that has at least the same specification. I'll take a look on this diode code tomorrow, there are references for 12A smd common diodes and zener diodes. Although if it was an zener diode it probably would be marked as DZ1 or Z1 on the board. It also could be a TVS diode (suppressor diode), these types are used to protect sensitive components against transients and voltage spikes. By the photos, It looks like the diode code is not MOD 12A. I cannot identify the last letter on the first line, the first one is an M and middle one looks like a D. Maybe it says MDD? On the second line I can see clearly the number 12 but cannot identify the last character. Maybe the code is MDD 12A or MDO 12A? You could remove this diode and test to see if there are any shorts between the 12V, 5v and GND rails. Do you have a multimeter? If it is a TVS protection diode, you could remove it, and test if there are any shorts left on the board. If no more shorts could be found the board may work without the diode for testing purposes. Is extremely advisable to find a suitable replacement. You need to make sure that there are no shorts on the board if you intend to test it. If there are any shorts on the board and you plug it you could damage the power supply, the orange pi or the sata hdd/ssd. The diode could be the following: TVS diode: SMF12A (there are pictures of diodes from this manufacturer with the marking MDD - microdiode electronics) There are other diodes from mdd but since yours seems to be marked as 12A, I guess this one should be the model you are looking for. https://www.lcsc.com/product-detail/TVS_Jiangsu-Yutai-Elec-SMF12A_C123800.html https://datasheet.lcsc.com/lcsc/2401290930_MDD-Microdiode-Electronics--SMF12A_C123800.pdf As I stated earlier, you could replace this diode with any other that has similar specification. TVS diode: P6SMB12A (from littelfuse) This manufacturer also has a 12A diode that has close enough specification. https://m.littelfuse.com/~/media/electronics/datasheets/tvs_diodes/littelfuse_tvs_diode_p6smb_datasheet.pdf.pdf TVS diode: SM15T12A (from sgs-thomson) This manufacturer also has a 12A diode that has close enough specification. http://elektronikjk.pl/elementy_czynne/diody/SM15T6V8C.pdf

This component in the circled area is a diode. It is possible to confirm it by the silkscreen on the board, it is labeled as D1(Diode 1). The other components up on the silkscreen, C281, C279 and C280 are the three smd ceramic capacitors above the diode. The diode looks damaged, but the photo is too dark to confirm it. You could clean it a bit and try to read the code of this diode. Another way to get this information is by searching the schematic, if available, for this board and look what diode is D1. Also you should check the component U16, it looks damaged, but again cannot say for sure, the photo is too dark. I guess this board provides 12VDC and 5VDC for the sata drives. Maybe the U16 is the regulator responsible for the 5 volts, cannot say for sure as I don't have this board or it's schematics. You could replace the damaged components, it may be an easy fix if nothing else is shorted. You should also check if nothing else is defective, don't know if you are experienced with repairing electronics. If I found the schematics for this board I'll post it here. Can you read the code on the diode? And about the orienting of the diode, I guess, by the looks of it in this photo, that the cathode side is towards the silkscreen that says 12V. In diodes, the side with the stripe marking is the cathode and the other side is the anode.