Burnt board

[docjones82]

What would you like to know?

I have a chip think its regulator for usb but not sure wondering if I can find out what is purple circled chip looks burned on mine and if plug usb and portapack h2 in together screen flashes and act up like shorted fine if usb not plugged in but need to charge pack

[martinling]

The part circled in purple is Q5 which is a PMOS transistor. Its purpose is to cut off the supply path from VBUS to VIN, to stop the HackRF being powered from USB when an accessory board (like PortaPack) is supplying VIN instead. It is controlled by the VBUSCTRL signal which comes from the PortaPack.

The Q5 part we currently use is Yangzhou Yangjie part YJL2301C which is rated for 3.4A drain current and 20V drain-source voltage. If you want to replace it, you can use any other SOT-23 PMOS transistor with the same pinout and similar ratings, there are many possible substitutes.

In normal use it should not be possible to blow Q5. There might be a fault on the PortaPack that has caused it to draw more than the rated current through Q5 while trying to charge from USB. The fact that everything still works from battery power when USB is not connected, suggests that the rest of the HackRF board is probably OK. If you replace Q5 then it should hopefully be usable again. If that works it will also confirm that there is a fault on the PortaPack side.

[docjones82]

I think it was powered on when it got plugged together or taken apart is what happened