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This is solved. Found PP3V3_G3H_RTC fluctuating around 1.6V-1.7V at L6960 and L6961. After a closer look at U6960, found corrosion on the outside of the chip. Replace U6960 and everything is good.

Hi Everyone, I have this board 820-01700; no history, no liquid. it’s not recognize in DFU/ Apple Configurator. Reading on meter is 5V, ~0.455amp; reading taking with board outside enclosure. PPBus is fluctuating ~ 8v. Slp and awake power is cycling from U7800. I can not find any...

So happy, got it fixed 2informaticos. You're the man. Following your advise, I start measuring the mosfets Q8201-9 and found they didn't have the 12V in pin 3 on them which was the PP12V_S0_BKLT_PWR. This line came out of Q8119 and there is a fuse before it, F8100, and this fuse was...

I do have 70V at J8200. I just replaced the backlight controller, still no backlight. How do I measure Return LEDs. thanks

Thanks for the quick reply; I measure the return lines and got around 22V. The measurement was unstable, seems like it was jumping around, maybe its the meter or not grounding right. is there a correct way to measure these? Please disregard the measurement previous post at j8200...

Hi All, I need help. This board has no backlight. One backlight output capacitor blew out and shorted. I've replaced it and still no backlight. I test with another known good display from an iMac 27" 2015 5k, but no backlight then test the original display in another iMac 2015 and the...

Yeah cpu is not worth it, but will at least try cpu mosffets and controller similar to 820-3662 before giving up. What apps do you use to run the extended Ram test. Is there a controller that handle GPU switching on this model?

If set on default on discrete GPU, it runs fine, no issue, and it wakes up properly. And it’s even seems cool while in sleeping mode. If you run normal, which the system will most likely runs iGPU, then it won’t wake from sleep and while in sleep mode, it gets really hot. you can set...

It's not working, maybe our programmer is outdated. We have a Hi-Lo Systems ALL-100A. We have this programmer for awhile, it's due for an upgrade. Put back the Bios from Ebay and it's working again, but still have the wake problem. Anyway I don't believe it's the BIOS issue, cuz' the...

Hi 2informaticos, it didn't work for me. I think I'm not doing it right. My programmer can normally flash "File" type and yours' is a .Bin type. I think I need to convert it to a "File" type. Here's a pic of the file. I know for sure our SPI Roms work because we have use it many times in...

Will do. Ty When it doesn't wake, I do see the CPU getting hot, and the fans will slowly rev-up. I'm thinking of cooking the CPU. Do you have any suggestions? Any help is most appreciative.

Yes, PRAM reset done. Test with both ext. USB and also wipe internal ssd and reinstall OS. After the PCH, it was super slow, so I bought a new BIOS on eBay and I was back to normal with the same issue. I'v been wanting to learn how to clean ME region in BIOS, but never got to it. If you...

#3 Hi All, The problem is that it will not wake for sleep. The board is clean, no history of liquid damage. Already replaced U9800, SMC, PCH and still same problem. It will work if I turn off Automatic switching / energy/ system pref. So it will wake if run on the discrete GPU, but will not...

OK. Thx

Hi 2informaticos, first time on this forum, but I have learned from you guys for awhile. I have the same problem. The board is clean, no history of liquid damage. The problem is that it will not wake for sleep. Already replaced U9800, SMC, PCH and still same problem. It will work if...