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Thank you 2informaticos, very helpful.

Yes, disconnecting cable that goes over I/O board caused fan to stop running at full speed. I wonder how this really works. Does BJT starts conduction when temperature is high or something else? On the schematics, I can see that base and collector of BJT are shorted, and for the NPN transistor...

First you should download schematics. The thermal sesnors are shown on page 48 of the schematics (use Google to find it). There are two IC chips: U5850 and U5870. To these ICs many sensors are attached. U58050 is connected to "GPU PROXIMITY/GPU DIE/LEFT FIN STACK/RIGHT FIN STACK". This is most...

Thank you 2informaticos and piernov for the explanation. It is very strange to use use words proximity for thermal sensing since usually proximity sensors detects presence of an object in its vicinity. Anyway, @2informaticos, if you by "change LCD assembly" think this: that is ofcourse out of...

Hello guys, I'm inspecting the schematics of 820-3437 board and on page "Thermal Sensors"(page 44), there are a few acronyms such as: TBT,MLB, MLBBOT, TBD, CPU Proximity, Inlet ,DDR and BMON. What are these acronyms such as TBT TBD and MLB mean? How these sensors works? All I can see on the...

Thank you for the clarification!

Thank you piernov, but this is exactly what is hard for me to comprehend. If the output is floating, how come that pull up resistor ensures exactly 1.05V? All voltages around IC are 3.3 V and yet this 10 K resistor with 5% tolerance will pull up voltage to 1.05V so aacurately and precisely?

According to the truth table given in the datasheet, if both inputs are high (3.3V), the output is in the "Z state", whatever that means. When MOSFET works as a switch, and if Vcc is connected to the drain, and source is on ground, if the MOSFET is ON (conducting), Drain is connected to the...

farfan14, I can bet your reaction after opening your Macbook was similar to this one (timer set):

Hello guys, I'm studying the schematics trying to understand what different IC chips are doing. I have found one chip particulary interesting and I must admit I cannot understand what it is doing based on the data sheet. The schematics is shown in the attached picture. The output is used to...

Hello guys, if after visual inspection traces of corrosions are detected around pins of IC chips and resistors/capacitors, is it really necessary to replace the components? I wonder if it may be sufficient to desolder components, clean placeholders /pads on the board and return the same...

Hello macbook repair specialists, I havw watched many videos from Louis Rossmann doing repairs. I have noticed that majority of laptops he repair in his videos are MacBook Airs. Now is it because Macbook pro is simply that better quality (I'm talking about 2013-2018) or simply more people buy...

Brunomotter, had recently an issue with U8030, which is also the same load switch. Remove U8020 and inspect closely in what state are the pins on the board. It is possible that pad for enable signal is damaged and that EN voltage is not really getting to the switch. Both Vin and Vout have...

Holly crap Batman, after removing C8186, computer booted without any problems. It works correctly. When testing cap with digital meter on continuity it doesn't beep, but diode mode shows something like 060, which is very unusual.

No, I didn't. So your suggestion is to remove this capacitor and check again?

Hello guys, I have a board 820-00165-A with strange behavior. When connected to the charger (board on the working bench), fan immediately starts spinning at full speed. Investigating different power rails I found out there is no PP3V3_S0 and I also found that I do have PMP_SLP_S3_BUF_L = 3.32V...

I'm sorry, I wasn't clear enough in my previous post. What I want to say is that according to the schematics, PP3V3_S0 is created from PP3V3_S5 when signal P3V3S0_EN is high, and this enable signal is directly derived from PM_SLP_S3_BUF_L/PM_SLP_S3_R_L after 0 Ohm resistor (essentially fuse)...

Yes it is interesting to see that S3 is used t create enable signal for S0, but actual S0 voltage is created from S5 state.

Hello guys, I have a question about different power states of the Macbook. I understand what they are and I understand that all of them up to (and including) xxx_S0 must be at correct voltages. Now, If I close the lid, the system goes to sleep and enters state S3, does it mean that all _S0...

Thank you 2informaticos. I also have 8 mm nozzle that I used most often. What is 400/2, I guess 400 is 400°C, but what is 2 or 3 in 450/3?