Printer suddenly stops, baud error, no connection anymore

[marble 0]

Hello,

I am trying to find a solution for the "freezing" problem which is torturing me since ever! I bought the UM a couple of years ago, it has burned 3-4 kg of filament almost without problems... just some random stops.

I mainly use Seven 64 bit with a laptop and a pretty big UPS to prevent blackout problems. I do not generally use the laptop when I am printing (no bt, no wireless, nothing).

In the last months the "freezing" (no connection) problem has become more and more a hell of an issue especially because I am printing bigger objects and after lots of hours it is not funny to throw everything out of the window.

So I decided to buy a new arduino 2560 board, I thought that it could have been a solution? I uploaded the marlin firmware, connected the board and printed a couple of Ultimaker robots. I noticed everything was going smootly so I decided to put an extra function, the "filament changer" plugin. It went straight from the start to the end without stopping, I did not have the chance to change the material though. But at least it finished the object

I started the forth object but suddenly it has stopped to work, again. This time completely. No sign of connection.

I tried in vain to see the connection from Cura with Seven64bit then Mac (Yosemite) and Debian. The last one has at least made the led blink, the RX blink, even though the result is still "Baud Rate Error".

On the main board:

- capacitors checked

- resistors checked

- link between arduino pins and drivers checked

- darlington changed

- drivers changed (now A4988)

I have the heating bed with the 4,7K resistor placed on R4 and a 100K temp sensor. The temperature is pretty precise (I used IR thermometer) and the relay works (worked!) well.

Anyhow, even though something was wrong on the mainboard shouldn't I manage to see the arduino board at least?

can anyone please help me?

Thank you

 

[marble 0]

Update: using Arduino software I can see the board and upload Sketches. The "blink" one works good.

Now trying to find the official ultimaker firmware