Extruder not working on new RAMPS board

I have completed building a new RAMPS 1.4 board kit that I recently ordered. It was the Ultimachine pre-surface mount soldered kit. I did all of the through hole soldering and everything works except the extruder motor on E0.

Every time I try to run the extruder motor, it does not move and it emits a high frequency noise.

I have working X, Y, and Z axis with mechanical home switches working, and my hot end and thermocouple work as well. I am using RedSnapper. I swapped the E0 pololu driver with Y axis pololu driver and then ran the extruder again, same noise. I swapped the motor cable of Y Axis and E0 Axis and homed the Y axis, the extruder motor spun normally until I hit the Y end stop switch. When I clicked the button to run the extruder with the motor cables still swapped, I got the same noise from the Y motor. I believe this means the problem is in the board. I re-flowed the solder on the E0 pins, retested and got the same high frequency noise.

Does anyone have any tips to help me troubleshoot further?

which host software are you using to communicate with the RAMPS board? if it is repsnapper the default speed (3000) is way too high for the extruder
bring it down to about 1400 and test it, it should work after that

I found this morning that when I touched the wires on the Z axis, the E0 would spin real fast at 1400 speed setting as you suggested. Without touching it, the E0 did not move.

I found the pololu drivers were sitting so close together on the x,y,z runner on the shield, that some of the solder connections that I made on each pololu were contacting the adjacent pololu solder joints. I re-flowed the large ones and put a small piece of tape between the drivers to insulate before re-seating them.

Now all 4 axis work, however my speed on E0 is very high at 1400. On my old setup I had been using the official Reprap host software with techzone gen3 electronics, but a modified pololu driver off the motherboard because my extruder chip fried, and I could extrude via the host and purge the hot end at "3000mm/min" and it worked very well. I am new to Redsnapper and to the RAMPS so I am still navigating the differences in software, but @ 3000 in Redsnapper it the larger gear turns about 1 revolution per second, WAY too fast.

I have to bring Redsnappers extruder speed down to about 100 to get a reasonably movement of the motor comparable to my old setup. Everything else is waaay too fast, why is the default 3000? What is the speed setting supposed to be set at while printing? Or is there a firmware setting that I have to configure to slow things down?

I'm one big step closer to having it working again.

Is it possible that you were using microstepping with your old setup and not with the new one?

Just a thought,

misan