I'm really surprised that nowhere in the article does the author mention putting an oscilloscope on either the power rails or the clock signal. Normally when I'm troubleshooting broken devices those are the first things I check.

A multimeter can make it look like a chip is receiving the correct voltages, but there can be all sorts of noise and fluctuations that will cause really strange and inconsistent issues. You don't need a super fancy scope, even a 100mHz cheap handheld is more than good enough for checking power rails.

Also, for anyone who has to troubleshoot or fix boards, those smd resistor and capacitor kits are absolutely invaluable to have on the bench. After a decent scope, meter, and soldering station I would say that should be the next purchase for setting up an electronics lab. Nothing more annoying than trying to debug an issue and having to wait for the right value cap to be shipped. Especially since capacitors specifically often seem to have some trial and error to finding the right value for something like a decoupling cap. Fully modeling the noise generated on a supply rail often isn't completely possible, at least in my experience.

Agreed on both counts.

20 MHz is well within the range of any random scope, and you should have at least one "any random scope" on your desk if you're doing electronics seriously enough to reach the "diagnosing QA fail boards" stage. So probe the damn thing - and see if the crystal ever reaches a stable operating frequency once the board is powered. That would tell a lot.

And yes, the "holy book of SMD passives" is a must too. They cost you what, $40 each? And can save you days of waiting for the "right" passives to arrive when you need to test a circuit change. You don't need to have every size - footprints are negotiable when you're hand-soldering - but you should have at least one Book of Many Resistors and one Book of Many Capacitors.