LP133WQ2(SJ)(A1) Slows computer with LVDS cable connected

prodigy83

Member
I have a LP133WQ2(SJ)(A1) A1502 2015 MacBook Pro 13.3" Display Assembly. I have never heard of, or seen this issue before. I purchased an entire MacBook Pro (Retina, 13-inch, Early 2015), to use the parts off of. I purchased the exact same computer, but with the eBay listing saying the Mac was slow, so I thought most likely it just needed to be wiped out. This was not the case. I got the computer, and noticed how slow it ran, and the OS had already recently been wiped. So I took the display off so I could install it on my customers computer. Once installed, my customers computer crawled all the way from booting up, and in to the OS. I isolated the problem by using only the LVDS cable plugged in. As soon as I unplugged the LVDS cable and used an external monitor, the computer ran fast again. I tested this by doing the same with the Mac that I purchased, and got the exact same result. I did try using another LVDS cable I had in stock, but I must not have the right LVDS cable I am assuming as I read somewhere the 2015's are different. For the life of me, I cannot figure out why a screen connected via the LVDS cable would make a computer run slow? Can anyone shed some light on this? The LVDS cable the computer came with, is NOT damaged, is don't see any nicks anywhere either.
 

2informaticos

Administrator
Staff member
Try starting in Diagnostic mode; lets see if any error pops up.
The fan goes high also?

Just in case, disconnect webcam and test again with LCD connected.
PRAM reset done?
 

prodigy83

Member
Okay, I am sorry, I tested it further, and it is not the LVDS cable. The iSight or webcam cable when plugged in, this does make it boot slow, and run slow. Seems like the processor is throttling itself. Yes the fan runs at full speed shortly after booting to about half way thru the progress bar.
I did the diagnostic mode with the battery unplugged and got the following error codes: PFM006, PPF004, NDC001. What is weird, is when I open photobooth, the webcam does actually work.
SMC and PRAM has all been successfully reset each and every time.
I looked in to those error codes, and with one of them, I did see a lot of other webcam issues. Some talking about sensors. I did see plastic down inside the connector for the webcam, so I cleared this out, but the same issue persists. I tried doing multiple tests on the other computer and motherboard I had, and it still boots and runs slow with the webcam cable.
 

2informaticos

Administrator
Staff member
ALS problem, not the camera itself.
Keep the camera connected, but isolate ALS_SCL/SDA lines at J4002; cut off traces for pins 8 & 9.
 

prodigy83

Member
That worked! I used one of the mini files I have to file down the connector that touches the pad. Thank you so much!!
 

prodigy83

Member
I have another issue now with this board. It seems related to the power states (S0, S3, S5). The computer after sitting for a while, several hours, it wont power on. The battery is fully charged. The SMC reset works from what I could tell when the battery was not fully charged, but it seems to turn off and on fine after I disconnect the battery, hold the power button down for a few seconds, then replug the battery back in. I did notice that each and every time I need to turn it on, it does need the battery plugged in. I found a person on ifixit that said the below noted in red, the board has never been wet, but many things were very brittle inside:

POSTED: MAR 27, 2017
OPTIONS
There are 5 different power states of a MacBook Pro, and different circuits on the motherboard are responsible for these different circuits. The battery definitely seems to be charging (since the light changes colour), and the SMC and associated circuits seem to be functional since the SMC reset is working. So, the G3H and S5 circuit which are the "shut down" states work fine. That means that there is most likely an issue with an S3 (sleep) of S0 (full on) circuit of the motherboard. Have you spilled liquid on your computer? If so, remove the logic board and clean with 99% isopropanol.
The power button is not the issue here as this logic board turns on when the charger is connected automatically when the board is working properly, so no need to use the power-on or jump start pads. A bad battery will never be the the cause of a board not booting. I don't know what Shawn is talking about - there are definitely no "pressure sensors" on the board that requires the bottom case to be seated for the board to turn on. The board should turn on even if it's out of the laptop with nothing but the charger connected.
 

2informaticos

Administrator
Staff member
Once machine is turned off from macOS (software way), it will not turn on automatically if you disconnect/reconnect charger.
Unless you've disconnected the battery; or it lost the charge.

If you can reset SMC from the keyboard, power button should be good.
However, check exact SMC_ONOFF_L voltage when you press and release power button.
 
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