Help to identify destroyed transistor from a power supply's pool's robot KWADOO v.2

[Jean4634]

Hi guys,
Trying to repair a pcb from a power supply's pool's robot ( KWADOO v.2), i can't identify the burned transistor Q3.
Could you help me ?
Thks a lot
Jean

[CapLeaker]

Re: Help to identify destroyed transistor from a power supply's pool's robot KWADOO v

Looks like an LDO regulator to me.
Pin 1 GND, pin2 and tab Vout, pin 3 Vin?
Maybe something similar like an AMS1117
Or:
Pin 1 Vss/adj. pin2 and tab Vout and pin 3 Vin.
Pics aren’t that great to see where the pins go and what these resistors are. See where the pads connect to.

[redwire]

Re: Help to identify destroyed transistor from a power supply's pool's robot KWADOO v

It looks like a SOT-223 transistor to me, emitter connects to ground, collector to clamp diode and the load, base to that resistor and then a via to somewhere else. Like BCE or GDS.
I would follow the base trace pin 1 to determine what it is; N-ch mosfet (goes directly to PIC MCU) or NPN transistor (through another resistor to PIC) BCP56.

The PC board is a bad design - the transistor copper-fill area for heatsinking has a cut or island around it, so the heat stays local.
The transistor burned up because it was overloaded, so fix that first.

[Jean4634]

Re: Help to identify destroyed transistor from a power supply's pool's robot KWADOO v

Thks you both for your answers.
I think it was a transistor because of the inscription Q3. Under the microscope i could read the brand ON on the piece of the recto.After some researches, i found that it was perhaps a transistor P1F, but i'm not confident.If i follow the trace from the resistor (10 ohms), it goes to the negative of the two condensators ( ground ?)
If i found the type of this transistor, is it possible to replace it by one with three legs ?
Thanks a lot for your help.
Jean

[lotas]

Re: Help to identify destroyed transistor from a power supply's pool's robot KWADOO v

On p1f (sot-223) - pzt2222a

[Jean4634]

Re: Help to identify destroyed transistor from a power supply's pool's robot KWADOO v

Thks a lot, i'm going to search one in my junk.