| Electronics > Beginners |
| Identifying SOT23 Component |
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| ChrisGreece52:
Hello i am trying to reverse engineer a PCB but i have a problem identifying an SOT23 component. Given that SOT23 components usually are diodes or transistors i tried measuring the diode voltages to identify the nature of the component. In the first ic i got the following results 1(+) --> 2(-) Forward Biased Diode 960mV 1(+) --> 3(-) Forward Biased Diode 960mV 3(+) --> 2(-) Forward Biased Diode 960mV See problem is the third measurement which if it was an NPN transistor it should be open circuit but it displays a forward voltage of 960mV i do not know if the component is busted or not so that is another problem There is an identical component above (Markings are 493) and i got the readings below from it. 1(+) --> 2(-) Forward Biased Diode 960mV 1(+) --> 3(-) Forward Biased Diode 960mV 3(+) --> 2(-) Open Circuit Which tells me that it should be an NPN transistor. Again i am not sure if both components are operational thank you in advance. |
| T3sl4co1l:
Is this in circuit or out? Tim |
| ChrisGreece52:
Its on the pcb i did not remove it from the circuit. Do you think that is the problem ? |
| PA0PBZ:
https://www.diodes.com/assets/Datasheets/FMMT493.pdf :-// |
| ChrisGreece52:
I found the problem !!! it is not the transistor but that i left it on the board. As i was drawing the schematic i found out that the two transistors are connected together like this. Where the normal behaving one is the bottom and the one i got the weird measurements from being the top one. |
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