Chosen Solution
Hi everyone, this is the first time that I m asking something on this forum and I found a lot of useful things already but this time I have a question… I m new with everything that comes about electronics and circuits and I m trying my best to learn in order to do some “small” board repair. Recently I learned more about how to read a logic board schematics (along with a board viewer software), but what it’s not that clear to me is that on the PDF are not shown all the values of voltage and current that all the pins are supposed to have… My question is, how do you know if by taking measurement with a multmeter a pin (resistor or capacitor and so on..) has the right value or not? Thanks -P Update I m using a software called Landrex Test link, downloaded from here http://laptopserviz.bg/enview/bvsoft/ , would be nice to have a software that tells you all the properties of each pin Update Hi guys! first of all thank you for you answer .. I took some measurements and I could trace some power rails such as PPBUS_G3H and some more. Then, I decided to choose a random pin on the board view which is the R9720, Net: BKL_ISEN4 (logic board K29). The values for this pin using my multmeter are Ohm 0.07, V 0.01. Looking on the schematic I can not determine the right values that this resistor has to have, most probably I m looking in a wrong way but I will be more then happy if you guys teach me. Is it the POWER ALIASES another way to call the POWER SYSTEM ARCHITECTURE? I m using a dead logic board that I bought to practice with the multmeter PS: John I m in this forum thanks to the youtube school ;) Update Hi John, On the motherboard it says w89190EB56GCA K24 2.26G BETTER and it s a 2009 apple macbook pro motherboard. My intention is not to definitely fix the motherboard, first because it’s old and second because I bought it online as a motherboard that has backlight problems and I don t have the rest of the computer. I want to learn how this board circuit work and how to reveal damaged chip/R/C/L/F, hopefully, without be annoying but enjoying with you in this useful forum. In the meanwhile I bought a damaged macbook air that I should get in this days, in this way at the end if I ll be able to fix it I will be much more self motivated to keep doing that. I m trying to attach a screenshot so you can see where this resistance is located in the circuits .. I m not sure if I did well. Back to the question, how do I know what is the right ohm of this resistance R9720? Thanks
I don’t understand exactly what your getting at? Open the board view open the schematic go to POWER ALIASES use nets to locate where ppbus_g3h is hanging on the board and with the other rails , and so on down the line. The schematic does give voltage, see whats off and track that area. This type of stuff can take a month to learn its best to do some youtube school :) for yourself. And just to let you know once you learn to how read a schematic it does’nt matter if its apple or not.
PP5V, hmm, maybe 5 volts should be there. 47 ohms, hmm, maybe that should measure 47 ohms. Brains.
