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Understanding schematics

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per4manz:
I am new to reading schematics and had a couple of questions regarding an Apple schematic I am looking at:

There are several capacitors marked with package size 402-2. I know what a 0402 package is. And I know this is still indicating an 0402 package. But what is the “-2” part of the package? I am assuming a specified height, but once again cannot find an actual package specified as such or even a reference online to such a designation.

At the top of the schematic page for a back light circuit I see the following in the page notes: “BKLT:ENG - Stuffs 10.2 ohm series R for engineering builds. BKLT:PROD - Stuffs 0 ohm series R for production.” Several resistors on the schematic are marked as “BKLT:ENG “ @ 10.2 ohm resistance. However, since this is an actual production model, would I replace those with 0 ohm resistors if need be or stick strictly to the schematic designations?

Any help would be greatly appreciated.

helius:
The series resistors would be used as current shunts for external monitoring of the current to the backlight. Attaching a voltmeter by tweezers to the resistor (or probes to suitable test points), and dividing the resulting voltage measurement by 10.2, yields the current. When product testing has been completed, there is no longer a need for these current shunts, so they are replaced with zero-ohm jumpers. Presumably, the circuit will work either way, if it uses a current-mode supply.

I don't know the significance of the other question.

per4manz:
Thank you, Helius. That helps a lot as I was about to order resistors. So at this point I think I will be okay with 0 ohm resistors.

And yes, the other question is odd since 99%+ of the resistors and capacitors are simply identified as 402. That's why that one is throwing me off.

per4manz:
One other question: am I correct in my assumption that I can ignore anything marked NOSTUFF?

helius:
"NOSTUFF" means literally "do not stuff this component": the pick-and-place machine ignores them and does not put them on the board. After assembly, the pads remain empty. Usually this is for alternative components or subcircuits that were designed but later removed for cost or EMC reasons. The word is still "stuff" because automated assembly was originally for thru-hole technology and the components were being stuffed into the holes.

You can ignore them in the sense that they are not required. It can provide some insight into the circuit function, because the idea is that they would function if they were installed, possibly replacing another circuit element.

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