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New bios also did not help

All S5 and G3H Voltages are present and stable. And i can turn it back on instantly. SMC Bypass did not help aswell. Everything seems to be stable if the board is powered. When turning off every s4 and above rail turn off (as expected)

This 820-3437 turns on but also off again after a few seconds. I tested the board outside the case and same thing. after it turned itshelf off i can turn it back on without any problems. Sometines it turns off during RTC-reset and sometimes it stays on for a few seconds. But it never made it to...

Ok thank you. I'll check that and only get back to this of its not the PCH. But i think you are right...

I cant see a pulse on my scope on the SLP_Sx_L signals. Its also not turning on in SMC bypass mode. I also talked to the customer and he said that the charger was not attached but maybe it was just sleeping not turned off as he changed the cable. That would explain the spark on J4802. I checked...

If i hold SMC_ONOFF_L shortet PM_PWRBTN_L seays at 0.35 V. Should the sleep signals stay up while i hold SMC_ONOFF_L shorted? Or just pulse? I cant see a reaction of the sleep signals... PP1V05_SUS is present.

Actually i dont know yet. I told the customer that i see if i can find a solution/idea for this problem as i already disassembeled some of these machines testet another power supply and other stuff and glued them back together without success. So i dont want to do this work again if i dont have...

Thank you for the answers. Yes it turns off completely. I forgot to mention that it also wont turm back on after it turned itshelf off. I need to unplug the power cable to get it back up running. Also sometimes i need to unplugging it multiple times until is turns on again. Unfortunately i dont...

Hello, i had quiet a few of the 2012 27" Retina iMacs here that work fine (if the customes shows up) but randomly turn off. I could verify that issue and testet these machines alot. I am pretty sure that its a probem with the MLB as i could rule out virtually everything else at this point. I had...

All measurements are i took were with the board outside the case. I checked all the signals around U0500 and here are the Signals that go in U0500 (SYM 8 of 19): PCH_SUSACK_L = 3.3 V PM_SYSRST_L = 0 V PM_PCH_SYS_PWROK = 0 V PM_PCH_PWROK = 0 V PM_PCH_APWROK = 0 V PM_RSMRST_L = 3.3 V PM_PWRBTN_L...

PM_RSMRST_L is steady 3.3 V PM_PWRBTN_L goes down from 3.4 V to 0.35 V if i trigger SMC_ONOFF_L ald stays low as long as i short SMC_ONOFF_L On my scope i can see a pulse on SLP_S4_L a few seconds after plugging power in. But ist in mV scale. SLP_S5_L jummps up a few mV after plugging power in...

Magsafe working normally. Yes original 85W charger. SMC_ADAPTER_EN = 3.39 V PM_BATLOW_L = 3.35 V 3v3_S5 = 3.34 V 3V3_SUS = 3.33 V

Yeah that makes sence. I?ll ask him if he turned it off... 3V42 and PPBUS present and steady.

Hello, this 820-494 is dead after the customer swapped a faulty trackpad cable. He did not removed the battery and as he want to plug it in he saw a spark on J4802 (the corrosponding connector at the trackpad - not at the board). So i guess he shorted PPVIN_S4_Tpad to GND. Now its dead and...

Update: I could solve it with the help of another post from Duke. R4910 was bad. I was hoping for exactly something like that that i missed. So thank you anyways for the support and the possibilitys that this forum offers.

Hello, this 820-2936 was waterdamaged. I fixed all the corrosion and now it works again. The only problem is that its working slow and fan is spinning full speed. I run ASD and got 1 error: TC0C "unable to read sensor". I Already changed U5510, C5511, C5512 and verifyed R5510, R5511 and R5512. I...

I tested with other and no resistor but same thing... So i guess i leave the resistor off and deal with no KBDBKL control key... Better option for me as hope that another SMC will fix this and pray that it wont kill it again...

Thank you! I just put 3V3_S0 there and now it works at full brightness all the time now (24 V). I still kept the 10 MOhm resistor in place. Should i remove it? And is there anything to worry about doint this (except lower battery live...)? Like overloading the 3V3_S0 regulator or something as it...

I?ll check that but i need a few days to get a working board here. I would not really like to mess with the SMC again if no KBDBKL is the only problem as i dont have many donor SMCs and really dont like to swap SMCs praying that the "new" ones work... Would it be ok to put eg. 3V42 or 3V3_S0 at...

That measurement was taken with a scope. My equipment is not the newest so i cant show a better image than the one attached. Thats what the pulses look like. Scale is: 2us/div, 5 mV/div. I already testet another backlight modul but same thing...