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Does powering shorted board hurt stm32?

Hoorow
Associate II

firstly i am new to here, dont know much rules about posting. 1 minute ago i saw post about shorted power dont kills mcu but can it damage stm32?

so i shorted my 3d printer board(stm32g0b1ret6 probably) via 3.3v and gnd(general probably). i checked by heat and only 5v to 3.3v regulator heats up and melts solder flux except that 5v and gnd doesnt beeb at continuity test but 3.3v and gnd does it so i checked several capacitors and they beebs at continuity test, at schematichs there is much capacitors that connects 3.3v to gnd and these are dead by shock. 

can i fix my board by replacing just all capacitors? and does powering shocked board damages itself?

board is skr e3 v3 and im still waiting a solution from them but they dont do much

i will upload needed docs.(at shorted referance black is fixing bolts which is framed ground, yellow is resistor red is how it shorted).

thanks

10 REPLIES 10
TDK
Evangelist

If 3V3 was shorted to ground, the STM32 never saw any power and will be fine.

Capacitors, similarly, never saw any power and will be fine.

If 3.3V is still shorted to GND, you need to find out where and fix that.

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xisco
Associate III

You shorted 3.3V to GND. Those capacitors are of low capacity, and the probability of a fail of one of them for this cause is very low.

I think it's more probable that the problem is in the 5V to 3.3V regulator.

You can test separating the regulator to de rest of the board, removing the regulator or removing the coil L3.

If now the short disappears in the rest of the board, you confirmed that the short is in the regulator

Hoorow
Associate II

oh thats really good because i cant find exact mcu in my country but about capacitors they dont pass dc current so with continuity test if they beeb then shouldnt it be dead?

Everything on the shorted net is going to beep.

Check an unpopulated board first. Perhaps review the current netlist, and double check pin assignments.

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i tried removing 5v to 3.3v regulator and checked short without regulator being on board but there was still short at 3.3 and gnd but i will try removing L3 coil, okay i tried it with removed l3 coil there is still short.

so i should remove capacitors and test it ? if you meant firmware pin configuration as assignment there isnt any problem that can cause short

The capacitors are not the problem.

If there is a short from 3V3 to GND anywhere on the board, it doesn't matter where your probe, it will always show a short. Probing at each capacitor location isn't giving you more information.

As @Tesla DeLorean suggested, try probing a board which hasn't been loaded, if you have one.

Unclear what the "Shorted Referance.png" picture is showing.

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Hoorow
Associate II

okay i understanded capacitors but i dont have exactly same board to test it maybe old diffrent stock board can help.

shorted referance is exactly what happened before board died i forgot board got power and moved hex key to that fixing hole to unscrew but i missed so board got shorted by bolt via r52, i removed r52 r54 c58 c59 and there is still short

TDK
Evangelist

> board got shorted by bolt via r52

Ahh. Generally, such a short should not have a permanent effect on the board.

The AS1117-3.3 (typo for AMS1117-3.3?) is current limiting and shouldn't be damaged by such an event.

Not really sure what could have gone wrong if removing U6 didn't fix it.

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