Servo sometimes unresponsive

Hi guys,

I assembled my second Prusa i3 last week for my brother, and ran into a weird problem with the auto bed level servo. The thing didn't respond well, but only sometimes, and now it has stopped responding completely.

The problem:
- M280 worked.
- G28 extend worked, but sometimes it wouldn't retract.
- G29 extend/retract worked only on the first test point. For the second, every single time, it'd fail to extend the probe.
- Now, it doesn't respond at all.
- Weird.

On the magical world of google, I found a person with a very similar problem (maybe the same), but the topic was closed with no final answer.

Things I've tried:
- Putting 5v directly to the servo. I read that it could be a power problem, so I decided to take 5v from the ATX supply that powers the printer and just apply it to the servo, leaving only signal to the board. Didn't work.
- Testing the servo individually. The servo works just fine.
- Inverting the pins for servo(0) and servo(1) on Marlin assuming it could be a signal problem. Didn't work.
- Cursing the heavens. Punching the desk. Turning it off and on again. Didn't work.

Important note:
- During wiring, I reversed an endstop and managed to blow up the 5V regulator on the Arduino. This could be the problem, I understand, but I replaced the regulator and also tried powering the servo individually. Also, everything else works too.

Thanks in advance!

Sorry to insist, if anyone has any ideas It'd be greatly appreciated!

Hi Egar,

When you say you tested the servo individually, was that through the same mega ? I would try removing RAMPS. and connect the servo directly to the mega. Map the RAMPS servo pins to the mega pins and use those to perform the test.

Good luck!

I'll try that, thanks!

Fixed.

I'm embarrased to admit it was a freaking wire that was causing the problem. What threw me off track was the repetition: always failure during the second test point of G29, it had to be magic! It was that at that position the cable would lose its connection.

Thanks for the help and sorry to have bothered with this!