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Nothing on the screen. Just t2 heats up. I can push in DFU mode, but fails with error No liquid or corrosion around cd32s

Cleaned corroded traces and retracted. Replaced R8431. Turned on for a second saw loading logo. Switched off to test further, stuck at 20V 0.02A. T2 warms up, but pretty much stays only on it. Tried DFU restore fails repetetivly. Can't detect any shorts.

Found the issue. So resilient devices these non T2/Apple Silicon macs. This would have been corrupted firmware or blown IC with the new ones. Thanks again

Yes I can see the image and user login screen, no backlight DP_INT_EG_SL_HPD - 3.29V Also tried PRAM reset, no change

Got this iMac with customer DIY replaced SSD, since then it turns on with no backlight. Unlike the Macbooks, it doesn't seem to have backlight boost line on the main connector, only plain PP12V_LCD line. Not sure how bent pin on 12V lcd line can cause backlight failure. J8200 cable seems...

Are you testing all screens on the same Mac? Could perhaps liquid failed something on the logic board?

Found the issue, R5712 was not passing signals due to oxidation spot under the U5700 sticker. Replaced and recreated trace between R5870 and U5700 Bizzare oxidation even if there was no liquid.

No short on major coils and caps PPVBAT_AON - 0.15V PP3V8_AON - 0V

Thanks again. Seems like it was a faulty U8070, although diode measurements were ok

Perhaps memory failure? Have you tried to run memory heavy or GPU heavy benchmarks and test?

No Liquid damage, slight oxidation around C2441 RP2712 Loads externally, stable. Only SSD not detected. SSD_PWR_EN = 3.25V SSD_RESET_L= 3.30V PP3V3_S0SW_SSD = 0.4V P3V3SSD_VMON = 0.12V U5480 diode measurements seems ok U3710 diode measurements seems ok Tried multiple SSDs and SMC reset. Can...

Located the issue to bad components around UN100. Thanks again. Some references for future cases: > PP1V2_NAND0 - 6Ohm > P0V9_NAND0 - 100Ohm

PP1V2_NAND0 side of the coil is the one which has low resistance I soldered a wire and pushing 1.2V. It pulls 5.2 and sinks it somewhere but no heat spots on either side of the board apart than the cable. That must be a dead short to the ground plate of PP1V2_NAND0?

Even at 1.2V 3A I am not getting any heat spot apart than the tip of the probe I am injecting with

Removed LN430, short stays on the NAND side. Injected 0.9V, sinks up to 1.3A and no heat signature on the board or SSDs. No direct liquid. Some corrosion around CN139/125/147 caps as well as CT054 No other shorts

Nope, still short. Seems like it sent battery voltage to clock line. Thanks @2informaticos

I have short on I2C_SMC_PWR_SCL with removed UD201. Game Over? No other shorts in the area

I2C_SMC_PWR_3V3_SCL has 0Vdc drop, traced the short to UD201. Replaced it now short is gone. Tested the case and battery on spare board all works and charges battery. On this board still has X mark on the battery, shows 1% and stays at 0.34A power on current. Says Replace battery Any...

Although the measurements were identical to a comparison board, something in U6500 was holding SPKRAMP_INT_L low which must be the reason it was detected but not operating either of the channels. Although I reballed both amps. Went and replace it and now sound is back. For reference -...

What I was referring to was in general. If a signal has _L or _H in the end does it means that to be enabled it needs low or High? Or does it means that it stays at that level as default and needs to flip to operate. I could not find reference to this and is not clear to me. So basically...