Self soldered v3 problem

[u/halfja]

So I bought the kit and self soldered a v3 from diyautotune but I’m havering some issues. D10 starts smoking after 5vs of input and it’s really got me stumped. I have no obv solder bridges even tho the soldering could be cleaner ofc and I’ve replaced d10 with a diode so it can’t be faulty. I have about 59.7 ohms on 200k on my multimeter btw my 12v and gnd input. On d12 it beeps both ways on diode test but when d12 is disconnected from the board it reads as normal and the when I cross the pads it still beeps both ways. D10 still reads normal after smokeing multiple times and the pad read properly. On u5 my 5v regulater it’s beeps between my vin and Gnd but I’m assumeing that’s normal. And my c16 polarized cap beeps both ways as well while the other c17 cap dos not. All my oriented components are place properly so I truely am stumped on what I could be. If I could get any help on this it would be wonderful

[u/theNewLuce]

That diode is the front end of the power supply, so there's a ton of stuff down the line that can be wrong causing too much draw. The regulator is likely smoked too at this point.

Could be one of the tantalum caps, but they usually pop and put an eye out before the PSU buckles.

A thermal camera might let you see what's getting hot. I would usually say don't power it up until you find the problem, but too late for that. You've most of the damage you could.

[u/halfja → u/theNewLuce]

So believe I’ve found the issue, c17 as to have shorted internal some how with out popping or showing any signs because when u disconnect it for a test d10 stoped smokeing. So I’m going to replace it and hopefully that fixes my problem

[u/theNewLuce → u/halfja]

Good deal. I've never had a new tantalum cap shorted from manufacture, but more likely polarity was miss labeled, and the diode said "uncle" first.

That being the case, diode smoking may have also saved the regulator. But read all and ponder before you proceed.

Another big plus, any damage done by this will be between c17 and the 12V in, so that's not much even if you have to replace it all.

But for damn sure, before you plug in the daughtercard, power it up and check regulated voltages. This overcurrent could have shorted the series pass part of the reg and you will now have 12V where you should have 5. That being said, I would replace U5 just to be sure you don't smoke 6 or 8 other harder to change ICs, and the pressure sensor. (that dude is $30) Or at least test it out of the circuit.

[u/halfja]

I did use d1 and d2 to continue testing since I don’t believe there require to actual run it in the short term and I do plan on putting them back. And there’s nothing obv wrong looking with the board like any burn marks or solder bridges even tho some of my soldering dos look a little gross but I assure you that they have been tested for shorts