Not sure if my control board is bad or what, but after completing the build of Nybble today, we calibrated it, got it up and running and were playing with the remote buttons. Everything worked perfectly. But after about 20min of playing, it lost stability and started rolling over. I turned it off to investigate the problem and found the servo on joint 13 (front right paw) to be extremely hot and seized up. I found a similar servo in my parts bin and installed it. It worked for a few minutes and then the same problems began occurring. Any ideas? What can I check on the board?
Thanks
Is it always joint 13? When it worked, did the cat walked in a balanced manner? Did the leg collide with the body frequently? Did it get stuck before getting hot?
I'd like to see a video of the cat's movements.
It's unlikely to be the problem of the NyBoard if it worked with the 2nd servos you replaced. I suspect the servo's brush got burnt. But It should only happen after a certain period of use:
https://www.petoi.com/forum/hardware/double-the-lifespan-of-brushed-dc-motor
If it was the same problem as the above post, you can fix it as described. If the brush looks good, it might be the chip of the servo. What was the spare servo you put on? Do you have a picture of it? It has to be a metal gear servo to avoid burning. TowerPro MG92B or MG90D can be a good replacement.
Moving your post to the Clinic category.
It walked fine for several minutes. As I was trying out the bottom row of buttons on the remote, its limbs and head flipped around and head spun 360deg (not quite enough to put tension on the servo wire) so I grabbed it and powered it off. After powering on again, it walked fine. But then shortly after joint 12 (I misspoke when I said 13 -- it was 12.) seemed to stop working, because when it tried to walk, it fell to that side and rolled onto its back. I tried a few more resets before I realized what was causing it. The servo seized completely; I can't even spin it by hand.
I replaced it with an SG90 but I will order another MG92B or D. Since the servo seized, I doubt the problem is the brush, but I will try to troubleshoot by disassembling it when I have time. I will update you as I progress.