curiousmarc
patreon
1 MHz Crystal and IC Post Mortem
🕑 Added 2020-10-06 07:18:50 +0000 UTCI had to know. I opened (carefully) the 1 MHz crystal that had failed. I suspected some kind of mechanical failure and boy, did it have one. Or many. A big bad scallop had been taken out, you can see where it hit the can. Also at 90 degrees of that, there is another mark on the can and a smaller chip on the crystal. This guy was hit pretty hard. And then to top it all, one of the contact springs had just separated. You can see pictures of both the good and the separated suspension contact. Looks like it was just silver epoxy holding it in place.
It's amazing it still showed a faint crystal behavior, the higher 1.001 MHz was because the crystal was slightly lighter from the fragments that were missing. I guess it just coupled capacitively through the open contact, and my HP VNA was sensitive enough to pick it up!
I also opened the CD4069UB hex unbuffered inverter. It was pretty easy because it was in a ceramic package. Just hit it at the seam with a chisel and the top will pop off. As expected, nothing particular to see inside except a beautiful die. It must have died the peaceful death of early CMOS chips, contamination or ion diffusion or whatever they used to die from. It is supposed to have only two transistors per gate and a couple protections diodes, so you can do your best Ken Shirriff impersonation and try to reverse engineer this chip for yourself.
Comments
Michael O'Brien
Not that unknown. I remember back in the bad old crystal-controlled ham radio days when people use to unscrew the covers on TI crystal cases and either rub the side of a graphite pencil on the side of the actual crystal to lower the frequency, or sand it on fine-grit sandpaper to raise it.
Travis Snoozy
I read the comment and smiled. Then I saw who wrote it and laughed. Your smartassery is duly noted and appreciated.
That'll buff right out.
