ultimaker original circuit board replacement issue - temperature reading 120?

[derek-bosch 1]

I've been having issues with the extruder motor on my UMO.

The motor seems fine, as it is driven fine when swapped with another driver (i.e. plugged into the Z axis).

It doesn't seem like the stepper motor driver is the issue, as swapping the driver had no effect.

So I think it is my main circuit board.

I bought a replacement on eBay from China. Plugged everything in, powers up fine, but the temperature

reading on the UltiController says 120 before I've even preheated. Trust me it isn't that hot out

this is supposedly a 1.5.7 ultimaker board. curious if they might have a different thermal circuit? (thermocouple vs thermal sensor?) Really curious suggestions on what to try.

[gr5 2,194]

Those chinese boards are so cheap and not very good quality so it's always best to buy 3.

I don't know if they have a different circuit but I strongly doubt it. more importantly did you load the right firmware onto the arduino on the 1.5.7? You may have loaded the UMO+ firmware by accident which expects a different voltage from the thermocouple. Also you might have to remove a 4.7K resistor possibly. Some of the temp measurement circuits use a 4.7K pull up resistor but I don't think you are supposed to use that for the UMO circuit.

Also if the extruder motor is fine and the driver is fine it's almost surely the arduino and not the PCB as there isn't much circuitry on the PCB itself. So did you get a new arduino with that new 1.5.7 board?

[derek-bosch 1]

Those chinese boards are so cheap and not very good quality so it's always best to buy 3.

I don't know if they have a different circuit but I strongly doubt it.  more importantly did you load the right firmware onto the arduino on the 1.5.7?  You may have loaded the UMO+ firmware by accident which expects a different voltage from the thermocouple.  Also you might have to remove a 4.7K resistor possibly.  Some of the temp measurement circuits use a 4.7K pull up resistor but I don't think you are supposed to use that for the UMO circuit.

Also if the extruder motor is fine and the driver is fine it's almost surely the arduino and not the PCB as there isn't much circuitry on the PCB itself.  So did you get a new arduino with that new 1.5.7 board?

 

no, I didn't get a new arduino with it, just the 1.5.7 board.

I also haven't updated firmware on it, so it might have UMO+ on it instead of UMO. I will try that later today.

the extruder driver wasn't good, but replacing it on the old board didn't fix the issue. which is why I suspected the circuit board.

[gr5 2,194]

Yes but there is just a straight wire between the arduino and stepper driver. There aren't any complicated components. Still it could have been the PCB. A crack in the PCB traces, a bad solder joint. Plus there are other things connected to the stepper driver such as a few resistors and power and ground but still - arduino is just as likely it seems to me.

Regarding temperature - definitely the wrong firmware will do it as there are SO MANY different temp probes out there for all kinds of hacks and of course the UMO+ uses a pt100 with a temp circuit board and the UMO regular uses a different circuit board (on the print head) and different table and some people replace either of those with other solutions.

You could measure the voltage on the temp head. The UMO uses a thermocouple and then it goes through a one chip tiny board and the 3 wires going to that board are power (5V) and ground to the board and temperature going back where voltage=0V is 0C, 5V is 500C and linear in between so room temp (20C) should be 200mv.

[derek-bosch 1]

assuming the FW is stored on the Arduino Mega board, I am still using the right FW.

(haven't replaced the Arduino yet, but I have one on its way). I did verify that my new

shield board does have the 4.7k resistors that my original shield board does not.

I hope to get more answers over the weekend. Thanks for your help, Gr5!

[derek-bosch 1]

removing the 4.7k resistor fixed the thermal readings, and replacing the Arduino Mega

seems to have resolved the motor issue. Still more issues to solve on this UMO, but

slowly getting closer!