Search results

how are the probe points between the U6100 and its termination resistors looking?

Q7180 died. The charger needs to see a load in order to put out voltage, and if Q7180 is dead it won't see a load. One way to confirm this is to cut off a good magsafe 85w cable and attach the ends to a DC power supply, set it to 18.5v, and use that as a charger. It won't care if it sees a load...

Is this the DC in board and cable meant for this machine? Airs of different years use different dc in boards and different cables.

How does the cable between the DC in board and the motherboard look on each side? This is the 821-1722 cable. Where was the corrosion from the liquid damage? It's important to know where the original corrosion was. 8.1v means the SMC(U5000) is not communicating properly with the ISL6259. Was...

$500 https://www.rossmanngroup.com/boards/forum/board-repair-troubleshooting/27082-macbook-logic-board-troubleshooting-guide-for-beginners

Is this 820-3462? 3492 does not exist.

You can inject current it's just 99% chance that what gets hot is the CPU. I would go for it and start with 1v and see what happens.

I am confused as to whether we are currently exploring RAM beeping or dead. If it is dead after RAM reflow my first question would be how/if at all did you shield the PCH or CPU during this process so excess heat wouldn't go to them, and was your hot air running over them?

Q7030 is shorted and always on. Replace Q7035/U7000 again as well with Q7030.

I hate promoting this $900 POS but any chance you have a thermal camera you can use to record this process?

That sounds like a bad SMC.

Measure the power rails with the charger connected, battery disconnected. Which are present, which are missing? I would start with PP3V3R3V0_AON. Is this present? If not, what is its resistance to ground? If resistance to ground is below 350 ohms, does removing U4700 remove the short circuit?

Ok, we're getting somewhere. So short circuit present with SMC on, short circuit gone with SMC off. One of two things is possible: 1) You put on another bad SMC. 2) The SMC you put on was good but you used too much heat removing it from the old board/reballing/soldering it onto the new board...

This one won't be easy by any means. Does ALL_SYS_PWRGD pulse with fan spin?

I don't know what that means. 2.828 what? Is SMC_PM_G2_EN present? What voltage?

The CPU requests vcore from the U7200 prior to U7200 sending vcore via CPU_VIDSOUT. If the CPU area were ht with corrosion there are two likelihoods. 1) CPU has corrosion under it. 2) CPU is dead. I would give it an ultrasonic at something very high like 80-85 celsius for a short time period...

R7918 being 0.5kohm means it is 500 ohms when it should be 100kohms. 99% of the time, resistors do not go bad by going down in resistance, they go bad by going up in resistance. Do keep in mind that the resistor is not all you are measuring here. On pin 1 of R7918 is PM_SLP_SUS_L, and on pin 2...

This is a discrepancy in measurements. On one hand, the SMC is getting hot and it is taking 0.47 amps on PP3V42_G3H. On the other hand, there is 124000 ohms to ground on PP3V42_G3H. It is highly unlikely these two can both be true at the same time. You said earlier that PP3V42_G3H had 124...

Give a diode mode reading for pin 2 of R5281 and R5280 with no power going through. Put the red probe on ground, black probe on pin 2 of R5281, and provide measurement in diode mode. Do the same with pin 2 of R5280. PPBUS_G3H is 12.23v instead of 12.56v because the SMC is not communicating with...

WHAT! I asked for resistance to ground on S0 rails and you replace U7200? WHY??? I do not need all this information, just information requested. :( Replacing Q7260 makes no sense since we have no reason to believe it is bad yet. Answer my question and as punishment for providing all this...