820-000165 SMC sensor issue throttling

[henry1347]

Hi! I got this 2017 board that needed a long press in the power button to turn on and the CPU throttled extremely hard. if I do a SMC bypass the laptop works perfectly. tried with disconnected keyboard/camera/DC-in Board etc and still throttles. Fan always stays low not high

I inspected the board and it looked pristine except a little liquid spill around the SMC and had a shorted cap C5125 from U5110 REFOUT
after removing the Cap the laptop no longer needs the long press to turn on but still throttles and fan low rpm.

still haven't replaced the cap. ran ASD EFI and passes everything, installed HWmonitor and checked sensors all show normal temps low.

The only things that look sus are the "PECI SA" sensor jumps from 0 to 42 C don't know if that is normal
and it shows the "CPU Rail" current as 14.43A. that looks High, and "Mainboard S0 Rail" 118W of consumption.
I suspect it's a current sensing issue? would love some insight on where to look next as I'm a total Noob.

[piernov]

Re: 820-000165 SMC sensor issue throttling

Start with replacing the cap. Don't leave random parts off a board.

[henry1347]

Re: 820-000165 SMC sensor issue throttling

Hi, finally took this board again, replaced the capacitor and realized that the trackpad was extremely hot to the touch, and it didn't work anymore so I replaced it with another trackpad and cable and the laptop no longer throttles but the trackpad gets extremely hot I guess something is shorting it and I can't figure where to look for. I haven't turned on the laptop anymore because I feel like its going to burn the trackpad as it gets extremely hot.
but before I checked HWmonitor and everything looks normal except :
Memory bank A1 128C
and battery drawing 254 amps
the laptop no longer throtles, but the trackpad gets extremely hot.
Any Advice?

[henry1347]

Macbook air Burns Trackpads but works

I have this 820-000165 liquid spilled. Everything works but the trackpad gets scorching hot! tested with other TP and flex cable and still the same it gets extremely hot to the touch.

And also SMC reset works but Option/Alt to get to boot or pram Reset or cmd+R dont work. I'm loss in what to look for as everything looks "good" Help please

[mon2]

Re: 820-000165 SMC sensor issue throttling

1) The logic board is p/n 820-00165

2) trackpad is using connector J4800. Remove the trackpad so it does not get damaged and confirm the voltages are correct as per schematic.

Confirm voltage of PP3V42_G3H.

Confirm the same voltage rail @ pin 19 of J4800.

sheet 36/76 of the schematic.

[Askic]

Re: 820-000165 SMC sensor issue throttling

The only things that look sus are the "PECI SA" sensor jumps from 0 to 42 C don't know if that is normal

I can confirm that this is not an issue. I've seen this on many A1466 MBAs and none of them had any issue because of that.

So, are you saying that after replacing C5125 capacitor, Memory Bank A1 now shows 128C?

Please examine closely HW monitor now and compare with the first picture you posted here. Perhaps one or more readings are missing from the list.

[henry1347]

Re: 820-000165 SMC sensor issue throttling

1) The logic board is p/n 820-00165

2) trackpad is using connector J4800. Remove the trackpad so it does not get damaged and confirm the voltages are correct as per schematic.

Confirm voltage of PP3V42_G3H.

Confirm the same voltage rail @ pin 19 of J4800.

sheet 36/76 of the schematic.

thank you. yes confirmed PP3V42_G3H in pin 19: 3.43V and in L7096 same 3.43V
also PP5V_S4_IPD pin 14 is 5.10V.
and PP3V3_S4_IPD pin 10 is 3.3V.
there is no short between the pins,
I think there might be some kind of short between pp3v3 and pp5v to Ground (via a data line?) as both of those lines seems a little bit more brown than the others.
but I checked every data line an none is shorted to ground and the trackpad and keyboard works. the only thing that doesnt work is the "Option and cmd+R" combinations at boots so haven't been able to run ASD EFI again

maybe a short via the usb communication but I'm lost on where to check next

[henry1347]

Re: 820-000165 SMC sensor issue throttling

I can confirm that this is not an issue. I've seen this on many A1466 MBAs and none of them had any issue because of that.

So, are you saying that after replacing C5125 capacitor, Memory Bank A1 now shows 128C?

Please examine closely HW monitor now and compare with the first picture you posted here. Perhaps one or more readings are missing from the list.

thank you for your reply!
Yes, the only difference is now Memory Bank A1 shows 128C everything else seems normal. but when I connect the charger it says the battery is drawing 254 Amps. but can't do nothing about that as the trackpad gets scorching hot the second the laptop turns on.

[henry1347]

Re: 820-000165 SMC sensor issue throttling

I checked every capacitor I could find for a short or a difference in the resistors rated Ohms on all the trackpad SPI lines and found nothing. also checked the trackpad usb lines but surely I'm missing something