Marxon Posted August 22, 2014 Report Share Posted August 22, 2014 (edited) Hi all! While working on my Midibox NG, I was careless for a moment and powered the STM32F4 core with too high voltage. :cry: Now it seems that something is faulty on the STM Discovery board because there is a short circuit between the GND and 5V pins (4 ohms).My first thought was to check diode D1, D2 and D3, but they are OK. Now i guess U1 or U3 might be have been destroyed but before i start to desolder them, i first want to ask if somebody might better know what to check . Thanks a lot for your help! :thumbsup: Best regards Marxon Edited August 22, 2014 by Marxon Quote Link to comment Share on other sites More sharing options...
mono Posted August 23, 2014 Report Share Posted August 23, 2014 4ohms between 5v and gnd sounds strange to me! but eventhough u1 and u3 are low-drop-regulators, they are not affecting the 5v rail, as they are 2,5/3v regulators. i would suspect c1 or c20 (next to u1/u3) to be destroyed from your "high voltage". these are the only ones, that could cause the "short". you can try to desolder them or even replace them, but for the price of the board, its not worth the hassle anyway... Quote Link to comment Share on other sites More sharing options...
Marxon Posted August 23, 2014 Author Report Share Posted August 23, 2014 Hi mono. Thanks for your reply. I noticed that U5 was getting hot, it is the only part which get's 2,5V from U3. So I removed U3. Now U5 stays cold. I also removed C1 and C20 unfortunately the short circuit remains. You are right, the board is not very expensive. Another one is already ordered but this means one week idleness Best regards Marxon Quote Link to comment Share on other sites More sharing options...
mono Posted August 23, 2014 Report Share Posted August 23, 2014 ...not sure, if we are talking about the same board then. u5 is the mems-sensor on page 36 of the discovery-manual. u5 is not getting 2v5 at all! its u7, the audio-codec, that needs the 2v5. but if you have removed c1 and c20 already, i cant see, where the short comes from. hopefully you have ordered not just one discovery-board! i have 2 of them which i use with different configurations, as im using different lcd-types. the other advantage of that is, that you have always one on the shelf in case the other gives up..:-) kind regards, mOnO Quote Link to comment Share on other sites More sharing options...
Marxon Posted August 23, 2014 Author Report Share Posted August 23, 2014 Hi again! ...not sure, if we are talking about the same board then. u5 is the mems-sensor on page 36 of the discovery-manual. u5 is not getting 2v5 at all! its u7, the audio-codec, that needs the 2v5. but if you have removed c1 and c20 already, i cant see, where the short comes from. :blush: :blush: :blush: Right again. Maybee U5 does not become hot anymore because in meanwhile it is completely destroyed... :sweat: hopefully you have ordered not just one discovery-board! i have 2 of them which i use with different configurations, as im using different lcd-types. the other advantage of that is, that you have always one on the shelf in case the other gives up..:-) Unfortunately not. In general i should work more carefully... (dear SIDs, please rest in peace) I have a additional LPC17 core but, because the lack of memory it is also only used to connect a different display. Hopefully i will receive the STM324 board soon. Greetz, Marxon Quote Link to comment Share on other sites More sharing options...
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