Macbook air 820-00165-A fixing

[bargo]

Ok back to this board now.

The status now, we have all signals and voltage present except that, no chime, no display USB blinks when inserted caps lock does not light up, power button works fine.

Charger starts with green then switches to orange with and without battery present. ppbus_g3h is at 8.1V does not change to 8.4V

inspected all lines that could potentially lead to why there is no chime but could not find any, the SMC seems to be functioning correctly. i also dont have a TBT_A_HV_EN thus L3095 is not showing any voltage. I thought I have a problem with U2800 because its the one that sends that enable signal, but I also think it should not be the case I have no shorts around that circuit.


The LPC_FRAME_L and LPC_FRAME_L_R are both present and I have activity on LPC_AD

SPI also shows some activity after few ms of time.

Any ideas to know what is wrong here?

[bargo]

OK reballed another SMC from the same model, with the same exact results

[bargo]

Now I will go to the UEFI cleaning part and see if that does anything.

[mon2]

Review the I2C / SMBUS lines. Someone may be tanking this interface and preventing the SMC from reaching the higher voltage.

What are the voltages on:

SMBUS_SMC_0_S0_SDA
SMBUS_SMC_0_S0_SCL

Disconnect the eDP panel and check again. If still low, needs to be reviewed.

There are other SMBUS networks and each must be reviewed.

[bargo]

Disconnect the eDP panel and check again. If still low, needs to be reviewed.

There are other SMBUS networks and each must be reviewed.

Thanks for sharing mon2. I will check it out when the bios chip is back in place. currently diving into this cleaning ME stuff

I checked the smbus_smc_5_g3_scl and sda and it was reading the battery information and stats correctly according to the oscilloscope.

I have not checked that specific one, I will plug myself into the bus itself and probe the devices on the bus and see what devices are populated and which ones are not. Once I fail with the EFI reflashing with clean ME.

All my best,

[bargo]

the clean ME did not change the situation. I have a clean ROM but same results.

The SMBUS_SMC_0_S0_SCL and SDA are still 0 voltage and thats due to the edp panel power not being raised on u8300. So surely it is low at this state, what would cause edp_panel_pwr to be low? as it comes directly from the processor.

it reads 1.3v on diode mode so its connected to the processor

[bargo]

One more thing, when I plug the charger while the battery is connected, the mainboard starts and fan start to ramp up. when all connections are connected and then plug in the charger it also starts but the fan PWM stays calm (managed apparently).


One more interesting stuff. Now I can see edp_panel_pw at 3.3volts but this happens only in ONE scenario. If i turn on the machine while the battery is connected and charger is disconnected.

I read 3.3volts as well on SCL and SDA of the screen. I see a very dark screen with no backlight even with a flash light on the screen i see it very black. also EDP_BKLT_EN stay at 0v

very interesting, now at least i can see the edp_panel_pw

[mon2]

Confirm the operation of the dual diode @ D7005. Remove all power -> meter in diode mode.

Red meter probe on anode (pin # 1); black to the common cathode (pin # 3) - should conduct. Reverse the leads and it should block.

Repeat with pin # 2 & # 3. Same results if all is well.

Do check on the voltage to ground @ pin # 3 with and without the adapter / battery. The higher voltage should pass through.

[bargo]

Thanks mon2 man

Confirm the operation of the dual diode @ D7005. Remove all power -> meter in diode mode.

Red meter probe on anode (pin # 1); black to the common cathode (pin # 3) - should conduct. Reverse the leads and it should block.

Repeat with pin # 2 & # 3. Same results if all is well.

It reads 0.249v on both 1 and 2 pins in diode mode.

Do check on the voltage to ground @ pin # 3 with and without the adapter / battery. The higher voltage should pass through.

with charger plugged i get 16v on pin 3 and 6.5v with a battery only.

[mon2]

when all connections are connected

Correct. An absent sensor means the logic board will assume there is trouble and kick on the fan into high speed. The trackpad is required to sense if the display lid assembly is open or closed. This signal will be used to enable / disable the LCD backlight.

[bargo]

Correct. An absent sensor means the logic board will assume there is trouble and kick on the fan into high speed. The trackpad is required to sense if the display lid assembly is open or closed. This signal will be used to enable / disable the LCD backlight.

ok interesting stuff as usual mon2, the trackpad is actually not connected only the keyboard is connected i will add the trackpad, to the combo and see if that makes the lid to light (I think it should)

I still dont understand why when plugging the charger i dont get the edp_panel_pw signal I only get it in the scenario i described (only with battery power source it shows up)

as we reached a level that this edp_panel_pw comes after about 3-4 seconds after the pw button have been pressed. Would that mean that SMC firmware is ok (im still worried about this blackbox chip)


Much appreciated, this was a very good hint, mon2

[mon2]

What is the voltage to ground of PM_BATLOW_L ?

[bargo]

What is the voltage to ground of PM_BATLOW_L ?

it measures 3.3v to ground

i connected the trackpad lid lights did not come in, edp_pwr_en is still at 3.3v (it also comes up if i remove the flex cable and keep the charger connected now, if i connect the flex cable it does not come up)

[bargo]

Also when the 3.3v is present on PP3V3_S0SW_LCD the DP_INT_HPD also gets a 2.7v it reads zero v when that rail is down. EDP_BKLT_EN is still 0v

And all of that happens when i start the mainboard with the battery power source.

[mon2]

Disconnect even the keyboard. Then test again. If required, you can use tweezers and short the power on/off pcb pads to mimic the power button. There will be a pair of such pads on each side of the logic board. In the schematics, search for SMC_ONOFF_L signal (R5115/16 pads).

[bargo]

Disconnect even the keyboard. Then test again. If required, you can use tweezers and short the power on/off pcb pads to mimic the power button. There will be a pair of such pads on each side of the logic board. In the schematics, search for smc on off (similar to this net name).

Do you mean disconnect everything except the battery and display? also flex cable and charger port?

or keep the extension connected?

its an absent R5116 for this board to trigger on/off

just tested it in both ways with and without the extension. Same results PP3V3_S0SW_LCD shows up after the first turn on and turn off then turn on cycle

the EDP_BKLT_EN does not come up.

Keyboard disconnected/camera/speakers/WIFI/SSD

question, this rail PP3V3_S0SW_LCD comes up because EDP_PWR_EN was triggered, does that mean we are post SMC firmware issues? or we may still have an SMC firmware issue. Or we are in a pre SMC firmware issue stage/state?

[mon2]

Disconnect even the battery. Also remove the bridge black flat cable that sits between the main board and the LIO board where you attach the MagSafe power adapter. Use your finger nails to gently lift the wider keyboard flat connector. Apply even lift pressure to lift the keyboard connector. Check YouTube videos if in doubt. Want the minimum hardware to test the board. Do you see the green power light on the MagSafe head? Clean the pogo pin power contacts with alcohol as they could have cat puke on them.

yes, those are the pads but I think the logic board will power on without the need to short the pads.

[mon2]

The board is power cycling? Do check the spi flash rom for voltages. There may be a high current event stopping the boot. Be sure the adapter is the original.

review this excellent website:

https://www.it-tech.com.au/mac-q-a/m...sequences/amp/

[bargo]

Disconnect even the battery. Also remove the bridge black flat cable that sits between the main board and the LIO board where you attach the MagSafe power adapter. Use your finger nails to gently lift the wider keyboard flat connector. Apply even lift pressure to lift the keyboard connector. Check YouTube videos if in doubt. Want the minimum hardware to test the board. Do you see the green power light on the MagSafe head? Clean the pogo pin power contacts with alcohol as they could have cat puke on them.

yes, those are the pads but I think the logic board will power on without the need to short the pads.

I dont like this tone my friend, I have no nails. Also I'm not very gentle, I like to break stuff.

Also the flat/flex cable is needed for that green light to comes up, so I'm not sure if I follow any of your suggestions now..

[mon2]

Throwing the kitchen sink at this.

with the lio cable connected, do you see the green led on for the MagSafe power head? Often the lio cable is defective between the 2 boards.

https://boards.rossmanngroup.com/thr...n-light.63378/

what is the voltage on SMC_RESET_L ?