Strange computer problem

Discussion in 'Technical Repair' started by Pfrrr, Sep 13, 2017.

  1. Pfrrr

    Thread Starter New Member

    Sep 13, 2017
    Hi! I don't know if this is the right place for this question but I have one problem with my laptop that's driving me crazy. So, after some time my ThinkPad Yoga decided not to boot anymore. SSD was always visible from UEFI and after failing to boot (just black screen) it would always show bootloader with options to boot Windows or to boot from SSD but whether option I would have chosen it would always throw me back to boot selection. I tried everything I could think off on software side but nothing helped. So I started playing with motherboard and found a way to boot it. I was measuring voltages on SATA connector and found out that if I measure voltage across GND and B+(RXP) pin on signal connector and turn on laptop it would boot every time! And when it comes to Windows loading screen I could just disconnect voltmeter and everything would work fine. After that if laptop isn't turned off completely (it could go to sleep and resume with no problem) or restarted, it would work just fine. So my question is- any idea what's going on and where lays the problem? Problem only arises during boot and it can be fixed by measuring voltage across these two pins (voltmeter acts as a resistor?) for a few seconds.
  2. joeyd999

    AAC Fanatic!

    Jun 6, 2011
    Possibly a surface mount pull-up/pull-down resistor was not soldered properly and broke free from the pad. Attach a large value resistor (>100K) between those two pins and see if that permanently solves the problem.
  3. wayneh


    Sep 9, 2010
    It resembles a problem with having a dead PRAM battery. If there’s a battery on the board, check it. @joeyd999 probably nailed it. I’m just throwing out another option if that falls.
  4. Pfrrr

    Thread Starter New Member

    Sep 13, 2017
    1M ohm resistor worked like a charm. Thank you guys!
    wayneh and joeyd999 like this.