A1sHB P-fet help

Discussion in 'The Projects Forum' started by ajt, Jun 29, 2012.

  1. ajt

    Thread Starter New Member

    Jun 29, 2012
    Hello, I just started reading Volume 1, the basics, so my knowledge of electronics isn't great... but I'm good at following directions, and doing the detective work.

    I'm currently trying to fix an xbox racing wheel that someone had given me. He had plugged in a generic power adapter into it, and said he smelled smoke... and that it would no longer power on. Apparently, he was unaware that he needed to match the adapters ratings to that of the wheel.

    Anyway, I opened it up and found a burned tantalum capacitor, and mosfet... everything else looked fine visually. So, I found a replacement cap, soldered it in, and it powered up. Connected it to the xbox, and everything seemed to work as it should. It's a wireless wheel, and had no issues syncing. However, I noticed that it powered itself on when I put in the batteries (3 AA's), and didn't turn itself off when the system was powered down (which it should). So I reexamined the board, knowing that it was probably the mosfet with the giant burn hole in it's center. :D

    I had already purchased what I believed to be an exact replacement, so I soldered it in. This time, the wheel didn't turn itself on, but when I pressed the power button it turned on for only a few milliseconds, then powered off.

    The marking on the mosfet is A1sHB (s has a line above it), and from doing much searching, I believe it to be an Si2301DS P-Mosfet.

    There are several datasheets that match A1sHB.

    There are the one's I found;

    and I believe

    http://www.datasheetcatalog.org/datasheet/vishay/70627.pdf (although this datasheet doesn't specifically state A1sHB)

    I believe I had matched it pretty well.

    This is the part I had ordered...

    Can anyone please tell me why this replacement wouldn't work? Is there something I'm missing?

    Here is a picture of the PCB...


    Q3 is the mosfet in question, and EC3 is the cap I replaced.

    Thank you very much for any help.