Recent content by protocold

tested removing ram modules and same symptoms… I don’t have another CPU.. is there other things I can test?

no, led601 solid, 602 blinks(try to come on and die and repeat) and others are off. I don’t have graphic card installed.

Turns out R2784 is blown open, Q2770 is burnt dark and pin 2 is shorted to ground Replaced Q2770 removed the short, replaced R2784 as well. Put back the CPU and ram, but now LED602 blinks.

ok, replaced DCIN board seems to fix the problem..

board will take a few try for MagSafe to turn on green light and then turn to orange light but will turn off the light without completely charging the battery. Have to remove charger and try again a few times for it to resume charging. the same charger and battery on a different 820-2850 board...

no it doesnt, no respond in SMC bypass mode.

sorry i have overlooked that while there is no obvious liquid damages but the TP around Q5490, R5033, Q5030 do have green corrosion, e.g. TP DCIN_5V_VSENSE, DCIN_VSENSE_EN, SMC_PECI_L_R etc.. also the solder joints around components in that area is somewhat rusted(under microscope)... does this...

where to start?

Replaced U7701 fixed it.

you previously show me SMCtool, which I haven't tried yet.. but since this board also use LM4F chip.. can I use one from A1502 onto this A1425 and flash this? But SMCtool doc said it is only for 2013-2017, this A1425 is 2012. I didn't see 820-3462 file... :(

let me try that, but can you enlighten me why it only provides 25v with the bad panel?

820-00165 with water damage(screen connector area looks clean), IO board replaced, cleaned the corrosion and the machine booted up. Survived MacOS install. An hour later the screen died(have backlight + white horizontal lines). Used external monitor and it output OK. Tested dead screen with...

C4901 = 3.36v C4902 = 3.4v C4910 = 1.2v AVREF_SMC = 3.3v by the way, battery was disconnected at all times, that is assumed right? Because you were asking battery bus...

SMBUS_SMC_5_G3_SDA = 0486 diode / 3.4v SMBUS_SMC_5_G3_SCL = 0.487 diode / 3.4v U7201: Pin 23 = 12.24v Pin 22 = 3.3v Pin 12 = 0v Pin 13 = 0v Pin 29 = 0v Pin 21 = 0v

original 60w magsafe known good adapter(tested), machine used to work but has been in storage for 2 years. No liquid damage. PPBUS_G3H = 12.24V PP3V42_g3H = 3.4v PP3V3_S5 = 0V PP5V_S5 = 0V SMC_RESET_L = 3.37v SMC_BC_ACOK = 3.2v now what?