GRBL sending garbled messages

[jimbo]

I recently purchased the M3 with all the upgrades. Assembly went without issue and everything booted up properly when powered. I homed the machine and started jogging around. Almost immediately, I started getting garbled responses from the GRBL firmware. Several times per minute I got corrupted idle messages. I tried sending a g-code file anyway and it stalled halfway through, presumably due to corrupted communications. This issue has persisted after trying three USB cables (one with ferrite beads as well as the short cable that came with the kit) and two computers running mac, windows and linux. I have tried UGS, source rabbit, and bCNC. I've made sure the usb cable stays away from other cables. It's always the same problem. Could the problem be a bad arduino board? 

[Bruce]

Sounds to me you've eliminated everything but the Uno board. You might check that the CNC Shield is seated correctly on the Uno board but other than that, I don't know what else you could check or change besides the Uno board.

[jimbo]

Thanks for the reply, Bruce. I guess I'll talk to the guys at MillRight before I spend more hours trying to sort this out. Would re-flashing the arduino be a logical step to take? 

[Derek the Admin]

Grbl itself may be corrupted somehow. I will send you over the hex file from the office tomorrow morning. If that doesn't work we will get you a bee uno.

[jimbo]

Thanks Derek, your help is greatly appreciated. I'm excited to get up and running!

[Derek the Admin]

Hey Jimbo. We emailed that over to you this morning.

[jimbo]

Thanks Derek. I will upload it to my board this evening and report back.

[Derek the Admin]

Sounds good.

[jimbo]

After several tries, I was able to flash the hex file. A couple times the arduino was not recognized when plugged in. After successfully flashing, I still had spotty comms and indeed it was getting progressively worse. At this point the arduino did not post as a working usb device more often than not. After some more research I believe the 16u2 usb/serial chip is to blame.
I loaded grbl on another arduino I borrowed and it works flawlessly. I'm now convinced the original board is bad. I'm happy to say I did some preliminary cuts with the borrowed arduino, but I have to return it next week.

[Derek the Admin]

We'll get one out to you jimbo.

[jimbo]

Thanks again. Please refer to my email and let me know how I can get the defective uno back to you.