[Device Repair] R7027:
What do you mean by external?

By system you mean the processor? That's assuming the signal is coming out of the processor and not going into the processor?

So by "system" you mean the processor? That's assuming the signal is coming out of the processor and not going into the processor?

So this would be pulled down to 1.8 V if it's going into the processor? And if it's below 1.8 V it may need to be pulled up if it's going into the processor? In other words, a processor simply talks at 1.8 V? Unless it's overvoltaged to 2.0 V or even up to 2.2 V for added headroom for overclocking (and shorter life span). I'm referring to PC processors (x86).

What does internal mean here? I recognize the acronym GPIO from my Arduino experiments. That's General Purpose Input and Output. I didn't know ARM SOCs have that too. I thought they had purpose built ins and outs, not generalized/universal varieties. You can tell how little I know, right?! :)

I'm not sure we're on the same page here.

The chipset is Exynos 8890 Octa (14 nm). The CPU of which is an 8 core (4x2.3 GHz Mongoose & 4x1.6 GHz Cortex-A53) and the GPU is Mali-T880 MP12.

Mongoose 1 or M1 for short is an ARM microarchitecture designed by Samsung and their first in-house design according to WikiChip. Exynox 8890 features one "big" core cluster of 4 of these and an additional "littl" core cluster of Cortex-A53. Interestingly, "big" and "little" qualify as technical terms. Very technical! LOL. For someone who can't tell size. Anyway! I could not find any specifics on M1, but if the "Juno ARM Development Platform SoC Technical Overview r2p0" document is anything to go by, the "core supply to the quad core Cortex-A53 cluster" is "0.8-1.0V". I believe the "Juno" is a device people in the know (and in need) use to develop their own electronic products based on ARM processors.

I will not pretend like I know all of this. I am just a good researcher and a decent google-fu practitioner. On the grand scheme of things, I still fail to see the relevance of this to my question of what the voltage should be level should be at that resistor.

What do you mean by test point? If you mean what end of the resistor I put the positive lead on, then no. Such information is not given in the service manual and I don't have the board view software needed to go in depth on that. But either side will give a similar reading of around 3.7 V.

I quote myself:

So negative lead on one end of the resistor and positive lead on the other end is the wrong idea.

The correct way to measure is to have the negative lead touch some point that connects to ground, like the metal around a screw hole or these metal shields, and then the positive lead on either side of the resistor. The difference between them is very small. It measures maybe 3.65 V if you put the red probe (positive) on the left end of resistor and it measures 3.70 V if you put the probe on the other side of the resistor. Can you maybe answer which value to note down? I keep running into this issue, and I keep notes of my findings (like a proper professional will do), so I keep writing down both. This I think is something I will learn with time, and once I get proper schematics of the things I measure.

I also wonder why some people will write down voltage as "5V" while others will write "5 V"? Is there no standard to this? Do you travel at 60mph or at 60 mph? I don't travel at either, because I use Km/h and there is always a space between measurement value and the measurement unit. But we have "Km/h" wrong too, because "kilo" is the only SI prefix that uses a lower case "k", so it should be "km/h". But Microsoft has it wrong too, because they write "KB" for kilobyte, instead of "kB". This depends on what version of Windows OS it is I think, or if it's MS-DOS. Anyway. I got carried away here. But please do tell me if there is a right and wrong way to write out 5 volts with unit symbols, I'm curious.