Ultimaker 2+ connected - bed heating stops at 40°C

[martin_cap_cz 0]

HI,
I need help with the bed temperature. The printer starts to heat up the bed, but stops at about 40°C and starts printing. It totally ignores the set temperature (75°C). I tried meassure the PT 100 - it has 116 ohms, so it looks be ok. The heated bed  has a resistance of 3.4 ohms. Anyone have any idea where the problem is?

Thank you

 

[gr5 2,271]

Your issue is most likely the sensor.  If the heater fails it should give you an error message.  And increased resistance anywhere in the sensor path gives you a higher temperature reading and so the printer things the bed is at the right temp when in reality it is cooler.

 

The sensor chip itself (PT100) is pretty much indestructable.  It's usually somewhere on the path from under the printer to the sensor.  The most common failure point by far is the connector on the board itself.

 

It sounds like you have some electronic skills.  If so it's actually pretty trivial to fix.  Take the bed apart - remove the 3 leveling screws.  Memorize or photograph or write down where the washer and stuff go.  The hardware at the 3 points is identical.

 

Take the bed apart and then check out the connector.  There are a few types.  The older types fail more often and the connector is soldered to the board.  If that is your case then remove the cable and reflow the solder at all 4 points although the sensor is the smaller traces and the smaller wires.

 

it could be that just removing and inserting the cable will fix the problem as the problem can occur at the wire portion of the connector.  The problem can also be at the other end of the wire under the printer.  Or it can even be on the traces of the circuit board - you might have to run two small wires from the connector to the pt100.  That has happened to one or two people.  But usually reflowing the solder at the connector is the solution.