I'd appreciate your help figuring out how to fix my RAMPS v1.4 board after I replaced the stepper motor and thermistor headers and re-soldered a broken connection to the F2 fuse.
If I plug any stepper motor drive into any position, the Arduino fails to boot
I can't sense the temperature of extruder 0's thermistor any more
Things that seem fine:
I have good connectivity pad-to-pad across F1 and F2
I have solid 12V power to X4
I have good connectivity between the 1A/1B/2A/2B headers for the drivers and the matching pins for the stepper motor connectors
There's no bridging between adjacent pins on the stepper motor connectors
None of the stepper motor pins seem to be shorted to either the Arduino GND on the double-header on the end of the board, or the grounds on the 12V supplies on the other end of the board
Pins 2, 4, and 6 on JP7 connect to the far side of their matching capacitors
Pins 3 and 5 on JP7 connect to the near side of their matching capacitors
Things that don't seem fine:
Pin 1 on JP7 does not connect properly to the near side of its matching capacitor: the resistance ramps up like there's another capacitor there. My multimeter measures JP7:1 to C5 as 16.4uF. C5 itself measures as 10uF. C8 and C1 measure as 20uF.
What should I check next to figure out how to resurrect this board? Before I re-soldered the connectors, it could control extruder temperature and drive the stepper motors.
The track around pins 3, 5 are almost destroyed. There's just enough at the top to connect with the multimeter. I hope this is something I can fix with a little solder paste; otherwise I'll have to try to solder new lines to the near sides of C5 and C8.