No time to go through the thread to know what is the issue you have on this, so most likely not related, but did you check the second pin top left (middle pin from 3 pins). Looks like a cold joint.
I can reaffirm that the microcontroller pins are not bridged, I've been using a jeweler's loupe to verify that they aren't connected. My camera wouldn't focus properly for that region, so I guess my word will have to be good enough.
I think it's set to 480F.
Yes. The joints looked like they weren't quite melted.
Thank you for clarifying. That's what it was looking like but I didn't want to jump in and buy something else if I didn't need it. Ok, something new to figure out.
Thanks for your help.Altitude909 wrote: ↑Wed Jun 24, 2020 2:57 pmwell it sounds like it works, its powering up. The 4 lit LEDs are how its supposed to look like before you upload code to it, not sure why you would toss it at this stage. There is no option to uploading code, you're going to have to do that on any MI diy project unless you get a preflashed chip
@extralifedisco, if you're still around, can you please clarify which capacitor(s) you're talking about in this message? I'm an electronics novice, but my guess is you're referring to C2, C3, and C8 (these are the 47u electrolytic caps before and after the 3.3V regulator on the Vcc line). Also, by "grounding a cap", does that mean shorting the Vcc/3V3 line to ground (i.e. the pads I've circled in blue below)?extralifedisco wrote: ↑Sat Mar 21, 2020 6:08 pmThat's pretty mystifying. It could be a leaky electrolytic capacitor - they should have basically infinite resistance, but if they're old or they've been overheated sometimes they don't. This can cause higher current draw than expected, overheat resistors, lower expected voltages. Have you measured the current draw on both rails and compared to spec?
If you want a quick and dirty test, power it up and wait until it shuts down. Then connect a lead to the PCB ground (alligator clip works nicely), and touch the other end to each capacitor's pads. If grounding one of them causes it to reset and turn back on, that cap is probably bad.
I removed the regulator, and it caused the current to drop to ~4mA (though the first time I tested it it remained at 260mA, so I spent a while hunting around the 12V rail for shorts... not sure why that would have happened, a capacitor holding charge maybe?).extralifedisco wrote: ↑Fri Jul 03, 2020 7:26 pmInteresting. It could be a capacitor, but that's an awful lot of current - that really is more likely to be a short circuit somewhere or a resistor value that's too small by a few orders of magnitude. A thermal camera would probably show you exactly where - or the touch test to see what heats up, but be careful not to burn your fingers. I would start by desoldering the LM1117 3.3v regulator. If removing that causes the current draw to drop down below ~50mA, then the short is probably somewhere along the 3.3v rail. If not, it's probably on the +12v rail.
It's possible the short is in the microcontroller itself, possibly due to an overvoltage on an input pin (have done this myself a few times). As a last resort be prepared to desolder it, test the current draw, and replace with a new MCU if needed.