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    T61 mobo & LCD woes

    Discussion in 'Lenovo' started by bgalakazam, Jul 2, 2011.

  1. bgalakazam

    bgalakazam Notebook Enthusiast

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    I have trouble with getting the LCD working on my T61. Currently I cannot get a working LCD in OS mode. Some of the LCDs work in POST and BIOS, others not. I am starting to believe something is wrong with the motherboard or my wiring because I NEVER get the 3 leds (power, battery, hdd) on the T61, no matter which inverter or screen I use. Only the wifi led works. Same inverters on my T60 work with all leds. Here is a bare setup of the T61, CPU, RAM, the long black cable (with or without, doesn't matter), LCD, speaker, keyboard.

    Info:
    - motherboard 42W7649 (14.1" non-wide, NVS 140M)
    - only wifi led works on T61, regardless of inverter
    - There is no problem in using external monitor, so GPU is working.
    - Speaker beeps work, but you hear a crackling sound when logging in Windows and when shutting down (short somewhere?)
    - I have tried testing all possibilities with stock BIOS and Middleton's BIOS. Results are the same, so BIOS is OK.
    - I have tried all 3 EDIDs in the complete qxga thread, same results (again, QXGA works like a charm on T60)

    Combinations (all tests were done with both 15" LCD cable from T60 and a 14" LCD cable from T61 == same results):

    T60 + 15" SXGA+/UXGA inverter (42T0079) + QXGA LCD = POST and BIOS and Windows/Linux LiveCD all work
    T60 + 15" XGA inverter (42T0077) + 15" XGA LCD = POST and BIOS and Windows/Linux LiveCD all work

    T61 + 15" XGA inverter (42T0077) + 15" XGA LCD = POST and BIOS work, Windows/Linux LiveCD no backlight
    T61 + 14" SXGA+ inverter (41W1479) + 14" SXGA+ LCD = POST and BIOS and Windows/Linux LiveCD no backlight
    T61 + 15" SXGA+/UXGA inverter (42T0079) + QXGA LCD = POST and BIOS and Windows/Linux LiveCD no backlight
    T61 + 15" XGA inverter (42T0077) + QXGA LCD = POST and BIOS work, Windows/Linux LiveCD doesn't work

    It is strange that T61 + XGA inverter powers on the QXGA up to OS, but the SXGA+/UXGA doesn't do that.

    Can you shed some light? I tried looking if there is a short somewhere, but couldn't find. The LCDs are working fine on my T60. The T61 is flawless when booting on external monitor. The BIOS is stock or Middleton's, no change. I have reset CMOS several times, no change.

    Any help would be appreciated as I would like to get my computer up to speed again. Cheers.
     
  2. bgalakazam

    bgalakazam Notebook Enthusiast

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    It's the 140M nVIDIA issue, I found out. You may lock the thread.
     
  3. ZaZ

    ZaZ Super Model Super Moderator

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    I might suggest if you want to keep the machine, buying a T61 board with the Intel GPU.