A2179 820-01958 slow, hot cpu core 4/5

PapaRayRay

New member
Came in, no power, liquid damage. Ultrasonic cleaning allowed me to power on and boot very very slowly. Keyboard back light area looked a bit rusty but was functioning I removed funky looking caps just to clean up and re-solder, continued working but computers very slow, I imagine it’s a sensor issue and maybe I’m struggling to determine which sensor it is and where to check, I believe I have checked the areas that I can gather are sensor related but to no avail. I have backed up the data successfully, I am not able to boot to an external drive the screen just goes black, same thing for recovery or anything else other than holding down the option key or successfully booting very slowly to the internal drive normally. The computer visibly appears to be doing the proper stuff to go into the DFU mode but is not recognized an Apple configurator 2.
hwsensorLB.jpeg
 
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2informaticos

Administrator
Staff member
Some heatpipe temp seems to be high too; can't read it in that picture.

Can you start in diagnostic mode?
Fan spins normal speed?
Did you try known good trackpad board/flex?
 

PapaRayRay

New member
Sorry, I chose the small file for the photo and I guess it blurred “heatpipe outgoing air 128° C” it doesn’t let me start in diagnostic mode, The fans seem to be spinning at a normal speed, I don’t have a good trackpad board on hand, this one “looks” to be fine I also had to ultrasonic clean that; I did however put a new flex. I also tried with the board disconnected.
 
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2informaticos

Administrator
Staff member
Trackpad board is the first suspect here.
You can also try disconnecting the webcam; is on T-CON board.

BTW, any reason to quote an entire post, visible few centimeters above?
 

PapaRayRay

New member
I ordered a new touchpad keyboard board I don’t think I have one, I’ll go through the rubbish at home to see if I’m overlooking anything; is there anyway that I can test if it is that without waiting for the new one, it arrives at the end of October and I didn’t have the option to make it faster freaking CHINA! Also about quoting the entire message I didn’t realize that I could just erase the quote I normally don’t hit reply I just do a new comment and while reading through other threads the other day I saw that you said it was smarter to hit reply.
 

PapaRayRay

New member
So, I am very much still in the learning stage; I did some googling and I spoke to the friend I have that is a little more advanced than I am. I’m not exactly sure what the T-CON board is I feel like this is it from what I gather. I tried a cracked display to see if it would change anything except the two cracked displays I have are insanely cracked so it’s very hard to tell actually more like I see the Apple jumping around on the bottom for what appeared to be very very long, I’m not confident that this is a good test so I would like to do what you’re saying with disconnecting the webcam which I’m having trouble figuring out exactly what it would be I don’t think it’s any of the flexes right? Maybe? Unless I’m wrong so I used the cracked screen as a test to make sure that I could remove the shields without damaging the flexes, if I have to remove the flex I certainly will. But I would like to know that I’m properly doing what you suggest. I guess that’s a long way of saying, What is the T-CON board and which is the webcam?5E39BBB1-B354-4CAE-8AC0-FDC5D954943F.jpegFE189BBD-6117-4880-A6B6-DDB1F8FA3098.jpegC26D3C15-A11B-429A-B2F6-E756FFD06857.jpeg25EC0513-D547-4C2E-A979-C26381512733.jpeg
 
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2informaticos

Administrator
Staff member
OK, the small connector near the video connector; that is for webcam.

BTW, disconnecting MLB video cable and testing with external monitor, has the same effect; no webcam available.
 

PapaRayRay

New member
Ty, I successfully disconnected the WebCam (doubt it’s relevant, I also checked to make sure that it works prior to disconnecting it and it did). Still very slow, still the same reading on HW sensors. Still only able to boot into internal (not in safe mode) I would like to correct an answer I gave you before; I have everything set up in my garage so there is a loud air conditioner and several fans, Saturday I did the WebCam test in a quieter setting; although the fan starts off normal after you login it definitely is spinning very fast. (Before I said the fan seemed normal) In the future I’ll make sure to remember check better before replying.
 

2informaticos

Administrator
Staff member
If the fan increases speed in time, then you should try known good trackpad/flex.
An issue with ALS interface (placed on webcam), is now discarded.
 

PapaRayRay

New member
Aite, what I could get my hands on fastest:
•Proper known good trackpad flex from same model
•1 2019 MacBook Air trackpad
•1 2020 MacBook Air trackpad board/flex and corresponding board (same year but from the M1 series)
I tried every combination of the parts above;
Nothing changed for better, or worse.
Upon removing the original trackpad it was a bit corroded like a little more than a little but not a crazy amount if that makes sense, ultrasonic cleaner did make it look a lot better, practically new except for the flex connector which looks healthyish but like it’s been cleaned, as opposed to the rest of it looking like nothing ever happened. Everything related to the keyboard and trackpad appear to work as expected.
I realized I forgot to mention at the start of everything I did have to swap the headphone Jack board (820-01992-0) with the exact same board and corresponding flex; as the original had fried the connector on the board/flex on part of it, the whole thing looked kinda bad so I chose to replace it (not sure if this is helpful info).
Also I guess I did most of my work here with the battery disconnected and became so engulfed in the temp and slowness, I missed that the battery says “service battery” and that it’s not charging (it does recognize the battery and shows the lightning bolt) idk if this maybe solely the battery or if it’s related to the issue we’ve been troubleshooting or it’s own separate issue. I’ll order a battery but don’t know if this is necessary to continue troubleshooting the issue at hand.
 

2informaticos

Administrator
Staff member
At least 01521 board doesn't work properly without good battery connected.
Its fan spins to max in such, case; as the symptom described for you board.
So get known good battery to test.

But now, as you told us about corroded audio board, I think some T2 data lines have been affected.
Usually SPKRAMP_RESET_L gets shorted (inside T2), being next to PPBUS_G3H on the audio connector.
 

PapaRayRay

New member
I try to do as much as I can with the direction you point me in to make the best use of your knowledge and learn as much as I can; I wish I knew more to make it easier for you to help me but I will definitely get there, I’ve learned so much since May this year. Thank you. I can’t wait to spend less of my time figuring stuff out.

•Battery eta 1/2 days from today.
•SPKRAMP_RESET_L: Definitely shorted, I removed R6402, C6104 just to be sure neither would be the cause and those are fine but short continues (I put them back.)
To be clear, when you say, “inside T2,” do I remove and re-ball T2? Or do I check else where? I clicked around and checked stuff I thought looks related and I think it was all fine everywhere else…
 

PapaRayRay

New member
And is testing on the two components and the corresponding test pad, like, I put the multimeter in continuity mode and checked if it beeps to ground with the board disconnected from power, is this the proper way to check if that is shorted? It beeps on all of that.
 

PapaRayRay

New member
FUN!!! Last question about this depending on your answer, if I was to purchase BY-T200 (unless there's something better) and Blank T2 ROM Chip would I be likely to move forward? (I stumbled on some videos in the past when looking up firmware chip programming stuff closer to when I started). If you think I can, then I'll order it now instead of sometime in the future.
by-t200.pngT2.png
 
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