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I made some more comparison measurement between the working conditions on the 13" (known good dispaly and board) and the 15" where none of the two display (known good 13" and original 15") gave backlight on the 15" board. I found some discrepancies with voltage values on the eDP connector. The...

I made some more comparison measurement between the working conditions on the 13" (known good dispaly and board) and the 15" where none of the two display (known good 13" and original 15") gave backlight on the 15" board. I found some discrepancies with voltage values on the eDP connector. The...

I made some more comparison measurement between the working conditions on the 13" (known good dispaly and board) and the 15" where none of the two display (known good 13" and original 15") gave backlight on the 15" board. I found some discrepancies with voltage values on the eDP connector. The...

Yes I did it but what sound strange to me is that the 13" display backlight works on the 13" MBP but not on the 15" one. I tought it should have worked on the 15" as well at least for showing backlight. If I connect the 15" display on the known working 13" MBP I also do not get any backlight. ???

PRAM reset didn't change anything.

For your experience do you think the 13" display should have worked with this 15" logicboard as the pinout is the same? Am I assuming this incorrectly?

Yes EG_BKLT_EN is 3,3V as it should

Just digged around and found EDP_IG_BKL_ON =0 Is there a problem with the PCH? In wich situation this signal should be provided by the PCH?

Got this laptop with little liquid damage spot around ISL that only prevented power up without battery connected and a shorted cap on the flash drive that prevented the drive to be recognized at boot. Fixing those problems, the machine powers up and boot but still without backlight. I of course...

I managed to solve this issue using scraped parts from an ethernet port of a desktop motherboard. Digging in to the metal encapsulated pcb mount RJ45 connector, I've been able to find a similar common mode choke (smt mount) and its relative transformer but trough hole mounting. I had to struggle...

Couldn't find any... Also couldn't find any datasheet of the LFE8904CF which is the packed version of the discrete transformer and CMI already used on another version of iMac. I also tried to look for the datasheet application example of the ethernet controller named BCM57766A but also in this...

I got this board from a client wich attempted a self upgrade of the NVme unit messing up some smt passive components o the board. The missing component are one LAN trasformer and its relative common mode choke. I've been able to find the type of product and may be the OEM (Murata) but they have...

Anybody capable to revive a machine like this in rossmangroup? :eek: Can't belive nobody went so deep in T2 problems solving yet. Hope someone can give me other suggestions in order to salvage this unhappy macbook.

Did you get any usefull hint from the resistance measures I provided you with?

No other hints? Should I give up on this?

Resistance to ground measured on L7410, L7430, L7210, L7230 is respectively 14, 14, 20,5, 20,5

I agree but I tought you could have helped me at least in order to get to a diagnose without these tools, I'm not talking about solving the issue right now but at least know what sould be the fault responsable of the issue. If I should blame cpu/pch or BIOS/T2 chip. I do not know if the DFU was...

Ok how do I know if the problem is with the BIOS/T2 or elsewhere? I tried restoring the T2 as I told you before resulting in just a padlock symbol and nothing else at the end of the process. I tought there could be something more straightforward to narrow down the issue.

Sure I'll do it but need your suggeasions about what to test next. I arrived at the point that s0 state should already be reached and I wonder why still not powering up. What should I measure to get a clear picture of what is working and what is not? Cpu/pch? How do I know for sure?

No, I didn't connect the battery during tests. I'll do it but I need to know if the problem could arise in CPU area or somewhere else in the motherboard.