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I was testing and saw low resistance on PP3v3_G3H_RTC at one of the CD3217 U3100_T. I thought easy problem. Swapped the CD3217, tested diode and was normal. Powered it up and nothing. Checked it again and it seemed like it was blown again same spot but then I realized that if I waited a while...

It was booting then suddenly I have dead short on PP3v3_G3H I have zero idea. I put some heat to SMC prior and it was up at 20V 0A and I unplugged and plugged back in and suddenly 5V 0A. I tried BPS to drive voltage through that rail and only thing getting hot is the wire and the point of...

Mouse tracking is sometimes unresponsive but sometimes works normal but it is consistently noticeable that it isn’t working correctly. This acts like a bad trackpad or cable but I tried both from MacBook that work normally and issue persists. I also connected external mouse and works normal so...

Yes. 87w

Hi there, this board occassionallyy will briefly take some amperage and drop just below 20V like its going to boot but 95% of the time it just sits at 0A and 20V. PPBUS is at 13V. All S5 rails are missing when in the 20V 0A state. I have detected voltage on CPU rails on occasions when it is...

THANKS!!

I thought this iMac had fusion drive issue or maybe was the original problem but I think there is issue with the bios. It will load mojave and big sur but has issues loaading monterey and ventura. I can boot them if drive is preloaded with ventura but it won't update and when trying to install...

Hi there,, I have a clean board that boots but is having issues reloading. When trying to recover it loads the OS through wifi and/or ethernet but after the first screen hitting continue it claims it can't communicate with the recovery servers and exits the install. I tried loading from...

Is there another signal I could use to trigger backlight instead? Customer would be happy if I could get backlight working even if it changed power consumption or it stayed on when it normally wouldn't. Could I pull enable on U8500 from LID or wake signal?

I swapped U9800 and still image no backlight. Is this one a lost cause you think?

Ahhh. got it thanks. Nothing there either. I checked diode is .62 there.

No, I mentioned in original post that EDP_IG_BKLT_EN is not present.

Pin 6 of U8500 is PP5V_S0SW_LCD also I do get 5V at J8500-45 I misread my notes the cap that was broken off solders but still next to them that i replaced =C8509 I get 3V42 for left and right SMC_LID Neither resets helped R8450-3 all check out. Diode for SDA/SCL @U8400 = .504 for both.

I've tested this with known good screen and also different LCD cable. At first I thought simple U8400 issue so replaced. No change as LCDBKLT_EN_L is not getting pulled down. SDA/SCL lines diode tests good and resistors are good. No edp_bklt_en. Discovered cap broken but still present next to...

This iMac boots normal. It then display goes off and doesn’t come back on. When display is off only 2 LED indicators on and no external display either. Sometimes it will come back on and reboot on its own , but usually it just stays off. It will with enough time boot up again with proper...

I ended up as last hope, reflowing PCH w/ flux and high temp enough to melt solder and it now is restarting normally.

No history. I tried heating PCH and also replacing SMC and new BIOS but no change. I think I will just replace the board unfortunately.

Yes U1950 good, Tried without Q8150. If I start in SMC bypass, then force off by grounding SMC_ONOFF, then triggering did start the board again but only briefly. Then you can see fans periodically start to spin but stop again and this continues. You think SMC is shit maybe?

Well you helped me discover some things I realized the board is cycling the rails even without triggering SMC_ONOFF_L. PLT_RESET_L is jumping to 3.3V every couple of seconds also. So if I shut the board off it seems to go to normal s5 state (rails are not pulsing), but once I trigger the board...

I did forget to add to list: yes PCH_INTRUDER_L is good also. PM_SLP_S4_L does go to 3.3V momentarily when toggling on/off while board is in state of being unable to start after shutdown.