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Can confirm. I have one in front of me that does nothing on the bench (20v, 0.07A), but when connected to a battery just boots.

History: customer may have left it on in a closet when they left their shop. After the weekend they tried powering it on and it wouldn't do anything according to them. All voltages look fine to me. Checked all rails on the 'power aliases' page in the schematic. This includes RAM voltages if I'm...

Working on an iMac for a change. No real prior experience (ripped the power button cable already) but as it's pretty much a MacBook on the inside, I should be able to work on this quite easily. 2 leds, no chime All rails present 5v rails are 5.1 - normal on these? or maybe just unloaded Some...

Ok, checked with a 140W charger, no change in behaviour. Noticed the heat pipe getting hot quite quickly after chime, so I'm guessing GPU at this point. Anything still worth checking here?

Ok, will try to get one with the right cable. Would have expected it to work on the battery though. Charging with a lower spec charger shouldn't be a problem imo. Edit: looking for a replacement. Are there different 2m USB-C cables from Apple, or should the current one I got with my 87W...

Got this one where it would get to 0,4A power draw and shut down after a bit. Restored firmware with DFU mode twice. Now it chimes but that's it: no image, no external video but responds to PRAM-reset. Pulls full power on 87W charger now. Not a lot of experience with these. Any pointers?

Checked external video, that's fine. Assuming cable replacement is not worth a try, will return as no fix. Thanks!

Works perfectly except for the screen. * Lines on screen when booted * No lines during boot * Doesn't boot with an A1708/2017 screen * No test screen available Behaviour does not change when moving the screen cables / moving the screen, so flexgate not likely(?). During boot: Booted:

One of the PWM lines measured above 1v to ground. Replaced corresponding transistor and it was around the correct 0.85v again. Fixed. Thanks!

Diagnostics result: PPF003, there may be an issue with the fan. Don't have a known good fan for a 1707, but tried one from a 1706/8, that caused the same behaviour but also the other fan to spin up, so no conclusive answer there. Sensor values:

All of those look fine to me, but I'll have another look. Any reason to use HWMONITOR over https://github.com/exelban/stats ?

This one came in with only 0V on one of the USB ports in one orientation. Changed the corresponding CD3215, first problem solved, it now has 20V and boots. Next problem, it now has a left fan that's on 100% all the time. Temps look ok (no reason for high fan temp wise). Ideas?

Spot on, short on PPBUS_G3H. Thought I'd checked that earlier, apparently not. Laptop is fixed now. Thanks!

No DFU / not recognised. pp1v2_awake 0v pp1v8_awake = 0.13v pp3v3_awake = 0.003v pp0v8_SLPS2R = 0v pp1v1_SLPS2R = 0v pp1v8_SLPS2R = 0v soc_red_SLPS2R = 0v

No visible damage, clean board. All cd3215's measure the same, no cycling on any of them. All 4 LDO voltages present for all, except BMC.

Ok, so this just failed again. Customer successfully used it to do a full backup a while ago, left it for a while (±a week) and today it worked for 5 minutes and died on him again. Anything still to try on this one or should I give up?

After a safe boot from an external MacOS installation, the laptop started behaving again. Installed Big Sur to update the BIOS for APFS support. Never tried this approach. I thought safe boot only disables 3rd party stuff. Does it also try to fix things?

I think I'm at the same point now. With 'working somewhat' I meant it was showing question mark folder. After Adding a bootable drive, I never got to an OS.

You mean the original, or reflash the new one?

Checked with new (iFixit) battery, still trouble. Gets stuck loading the MacOS installers a few tries and then only bootloops (turns on, fan spin, no image/bl turns off). Guessing CPU/GPU. Any other suggestions?