I miscounted the pins and ended up with my UNO connected GND to -12V and Vin to +12V. The regulator did not like that.
Questions:
From the schematic it look like I can pull the regulator and supply +5V directly. Is this correct?
What are the chances anything else was damaged? Is it worth spending the time to pull the regulator?
What replacement regulators are suitable for use int place of the ncp1117st50t3g? Ie. What are my options?
I've connected power the wrong way to things and got away with it, and I've conncted power the wrong way and got smoke....
Yes, pull the regulator and try 5V on the 5V pin. That's a better way to power it anyway.
Do you really want to put a new regulator in? If you have 5V available that's the best thing to power it with, not 12V.
PerryBebbington:
Do you really want to put a new regulator in? If you have 5V available that's the best thing to power it with, not 12V.
There isn't 5V available in the final power supply, only +/- 12V. For now I'm going to have to rig up a second power supply that won't fit in the enclosure until I can free or buy another UNO to replace this one.
There isn't 5V available in the final power supply.
In that case take the opportunity to use a buck converter, using a regulator from 12V to 5V wastes more power than the load consumes.
PerryBebbington:
In that case take the opportunity to use a buck converter, using a regulator from 12V to 5V wastes more power than the load consumes.
No space. I tried to find a 5/12/-12 DC-DC converter but for some reason adding the 5V output doubles the size and there just isn't space for it. Actually the +12V is adjusted to the minimum. The actual voltage doesn't matter as long as it is above 10V.
No space.
In that case I don't know other than find a regulator that will fit on the board. Beware of cheap Chinese anything. For myself I just wouldn't even consider using 12V as the supply, sorry.
PerryBebbington:
In that case I don't know other than find a regulator that will fit on the board. Beware of cheap Chinese anything. For myself I just wouldn't even consider using 12V as the supply, sorry.
The only thing running from 5V are the Arduino and LCD. So minimum load. It was designed that way. Everything else was spec'ed to run from +/- 10-14V from a 19.2V power source. It's an add-on to fit inside and existing piece of equipment.
A suggestion then would be to buy another Uno for the final build and keep the damaged one for experimenting with. That also has the advantage that you are not putting a possibly faulty Uno in your final design. Just because it works (if it does work) OK from 5V doesn't mean it has not suffered damage; the damage might show up later.
I would buy another Uno instead to waste time with finding and testing is it partially worked or whatever is with. IMO, it is much cheaper solution.
I have some time ago polarity connected wrongly several times. Results differs depending on total power and time it was connected. When it was short time, nothing was wrong with, other times some modules inside was fried and practically useless further.
If regulator died, sometimes replacements helps, however if 7 to 12 input voltage directly jumped to 5V output, the MCU was fried as well.
In your case, 28V difference probably make some more damage. All in all, not wort the effort to fix and test further as new Uno is quite cheap.
PerryBebbington:
A suggestion then would be to buy another Uno for the final build and keep the damaged one for experimenting with. That also has the advantage that you are not putting a possibly faulty Uno in your final design. Just because it works (if it does work) OK from 5V doesn't mean it has not suffered damage; the damage might show up later.
That I can agree with. 