help needed identifying diode

[Cupra]

Hi all,

This is my first post and I am a complete novice when it come to electronics but I am hoping you guys can assist.

On the attached quad copter control board the magic smoke appeared after connecting the a 5v line to a signal line in error... After expecting the board the diode was damaged. I need to replace the diode but don’t know how to identify the correct replacement for it. Please can someone assist in advising where I can find a replacement this diode...? It seems to have the number 15 on it but i do not know what this means?

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Thanks

 

[panic mode]

what diode? your arrow points to via. further away are three small SMD capacitors (non polarized) and one tantalum capacitor (yellow device, polarized).
if you are asking about component inside yellow rectangle on the left side, it is must likely Schottky diode.

 

[Cupra]

Thanks panic mode, yes I was referring to the component in the yellow rectangle.

 

[panic mode]

i thought so after posting reply. that is why i edited it...

anyway, the top side seem to be marked as cathode and connected to track marked 5V (if my eyes can be trusted).
most likely options could be Schottky diode for getting 5V from USB port or zener diode if anode was connected to GND.
it does not seem to be tied to GND because there is large ground plane right next to it. also track seem to go towards USB port...
unlike regular rectifier diodes, Schottky has low voltage drop and it is commonly used in such places to prevent backfeed
of power to USB when circuit is powered from external supply such as 12V (there seem to be 5V regulator AMS1117-5.0).
too large voltage drop (if using standard diode) would reduce "5V" rail for ICs below lower threshold so this is a job for Schottky
if the board was to be powered by USB only

 

[panic mode]

can you verify if this so far makes sense? is it how the diode really is connected? also what are it's dimensions?
to me it looks a lot like MSS1P5 or MSS1P6....

https://www.electro-tech-online.com/custompdfs/2012/10/mss1p6.pdf

 

[Cupra]

Yeah what you have said makes perfect sense. The top side is the cathode and is connect to the 5V. The dimensions are 2.67mm long, 1.6 wide, 1.1 high (from the board) - these could be a little off though..

I thought it may be a ss15 (https://www.china-diodes.com/e_showproduct.asp?id=484) but the MSS1P5 makes more sense and it is marked with a 15.

Thanks again panic mode I really appreciate your help with this. I will try get my hands on a MSS1P5, fit it and hold thumbs that nothing else is fried.

 

[panic mode]

SS15 is not suitable because of large forward voltage (Vf=0.7V). that means that 5V from USB would be reduced to 4.3V which is outside of tolerances for many parts (4.75...5.25V). this is why schottky diode is needed.

 

[Cupra]

ok, fitted the MSS1P5 today and I am ecstatic to report that the board is alive again

Thanks again panic mode

 

[panic mode]

congratulation... ;-)