No External Video after PRAM Reset

Discussion in 'MacBook Pro' started by daverice, Nov 30, 2014.

  1. daverice macrumors newbie

    Nov 30, 2014
    I call upon the MacRumors Sages! I am recovering a friend's MacBook Pro 13" Late 2011 MD313LL/A damaged by spilled water. It is out of warranty so anything goes. As soon as I opened the water damaged MD313LL/A I found the Logic Board badly corroded and knew it needed to be replaced.

    I purchased a MC724LL/A for parts to repair the MD313LL/A (on eBay reporting fixable issues). I tested the MC724LL/A and found it Option booted to Internet Recovery, but would not complete the process due to a bad hard drive. The Hard drive from the MD313LL/A did successfully boot without issues. That would solve the problem except for the broken right hinge mounting point on the screen and the dented mid-body just to the right of the Trackpad, making it impossible to click even though the cursor moved (issues not clear in listing). I subsequently used this track pad successfully in the body of the MD313LL/A, replacing the water damaged one there that did not work.

    I proceeded to replace the parts one at a time starting with the LB. I immediately discovered the LCD did not work and I had no video at all. I had a Thunderbolt External Video Adapter for external display. I purchased a replacement LCD display and after connected, I now had external video, but the MacBook Pro display still did not work. I also did not have working speakers. I performed a PRAM reset that restored audio, but now I no longer had keyboard backlight. I still considered that a win. I did not lose external video with this PRAM reset.

    I continued replacing parts one at a time, but at each step I could only get to a Gray Screen with nothing else. I continued replacing parts one at a time without joy. After I replaced all the parts from the damaged MC724LL/A into the perfect body of the MD313LL/A and still could only get the Gray Screen I tried a second PRAM reset. This time I lost the external video. I have tried disconnecting the battery, SMC resets and numerous PRAM resets with no joy.

    What can I do now? Did the LB fail? Did I somehow brick the LB? I hope there is a Wise Mac Rumors Forum Member out there that can lead me around this to finish the job or tell me it is hopeless and for me to move on. I also have USB Flash Drives with Lion and Yosemite on them that I used along the way as well, but they nor Internet Recovery would get me beyond the blank Gray Screen. On my first test of the MC724LL/A Internet Recovery, the MacBook Pro went a menu to reformat the disk, reload Lion and other choices after loading the initial interface, so I know what it should do for Internet Recovery after downloading the initial interface. Also, is there any way to test the LCD screen? I only have the word of the guy I bought the LCD screen assembly from that it works. I knew something was wrong with the original MD313LL/A LCD screen as there was no external video until I replaced it.

    MacRumors is great! I could not have gotten this far without the information in the Forum here. I just hope there is some Wise person out there to take me home or tell me to move on as the issue cannot be fixed. Thank you all in advance!
  2. daverice thread starter macrumors newbie

    Nov 30, 2014
    Additional Info

    OK after reading more on PRAM and SMC resets I found I was doing the PRAM correctly (Command, Option, P and R on starting chime, hold for 2 or three reboots then release and restart), but I was not doing the SMC reset correctly as I was disconnecting the battery and pressing the power button for 5-10 seconds. I found that for the MC724LL/A with a "user non-Serviceable battery" (come on Apple you have got to be kidding a tri-lobe screwdriver is not going to stop a reasonable person) you press Left Shift, Control and Option at the same time as the Power Button, release after 5-10 seconds then press Power to start. This correct procedure did not help, but now I know I did it correctly according to Apple.

    This also revealed a number of other things in my reading. The only thing not out of kilter is the video. I get a chime, the other lights and LEDs act correctly and nothing else is amiss, just the video.

    I used a flashlight to illuminate the screen upon boot and found that the backlight is not coming on. There is a dark, but seeable display on the LCD panel. So I have "tested" the LCD and found the backlight is the issue and the display does work. Now all that needs to be found is why the Logic Board had no trouble in the busted Mid-case and does not trigger the backlight in the not busted, but water damaged Mid-case. I also tried the original LCD assembly with the broken hinge mounting point too and did not get a backlight to come on either. I am speculating here as I did not try the flashlight thing, but that screen was fully display functional just a couple of hours before I swapped the LB to replace the water damaged one. I tried it after I could not get the original screen from the water damaged MBP to work on the swapped LB.
  3. poiihy macrumors 68020


    Aug 22, 2014
    PRAM reset should not randomly cause external display to not work. I think it was caused by something else. I think yo may have destroyed the new logic board.

    I recommend you give up with this. You are wasting your time and probably won't get far, if anywhere. For the price of buying all these parts, you could just get a new used MBP from ebay.

    Tip: If you plan to sell a broken device, take it apart and sell the working parts individually, rather than sell the whole thing in one piece. You make more money and make it more convenient for the buyers.
  4. daverice thread starter macrumors newbie

    Nov 30, 2014

    I tried one last boot mid-evening last night and lo and behold the external monitor started working again! I took that as a positive sign and used my flashlight to install Lion successfully! After the final reboot for Lion installation, the keyboard backlight started working. So now real progress! I still have the LCD backlight issue, so it is not all good...I wonder what caused this issue and what unknown, mysterious force corrected it. Should I close this thread since the issue resolved itself. I already know there are several good threads on the LCD driver chip and fuse/capacitor (not sure which after reading). I will be doing more reading on this today. Also the LCD panel could have a burned out backlight so it is not out of the woods as a suspect.

    After this experience, I am wondering about the External display. It shows something different from the MacBook Pro display. In Windows there is a mirror (duplicate) and an extended (additional desktop) modes. Could I have an extended display? I will be reading on this too, but thought I would ask now. If so, there must be a setting toggle in the software somewhere. Or I have some other issue with the external display showing a blank gray screen.
  5. daverice, Dec 1, 2014
    Last edited: Dec 1, 2014

    daverice thread starter macrumors newbie

    Nov 30, 2014
    Thank you

    Thank you Poiihy! I was about to give up depending on what the Forum came up with. The last boot changed the trajectory of this. Now all I seem to have is the backlight issue and the mystery of how the externàl display fixed itself. I will not be doing any PRAM or SMC resets any time soon! I did not have all that much money into this project, but an enormous amount of time. It was very discouraging to lose external video after all the work, so i posted here to see what the experts had to say. I also appreciate your advice on the parts selling if it could not be fixed. Hopefully I am on my way to full operation...
  6. daverice thread starter macrumors newbie

    Nov 30, 2014
    Persistence Pays

    Glad I did not give up...water damaged LCD blew 0603 fuse close to the LVDS connector. Replaced fuse and I now have a totally working MC724LL/A MBP in a MD313LL/A case!!!

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