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Bed Temp Sensor ER02

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I have an Ultimaker 2 Extended, and I'm getting ER02 about the bed temp sensor. I've swapped cables as advised by the troubleshooting site, but the error doesn't switch to the nozzle sensor. Am I correct that this seems like a board issue? I really want to get this printer fixed asap. It heats up just fine, but around 90 C the reading will suddenly jump up much faster to something in the mid or high nineties, then the error. I don't believe that the bed itself is heating too fast. I did manage to get one print after troubleshooting in an unproductive circle for some hours, but after that it went right back to erroring. Please, help?

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more info here: http://ultimaker.com/ER02

 

This is almost certainly a problem at the bed and not the board.  When things heat up they expand.  A contact along the temperature sensor path is a bad connection and when things heat up and expand it loses connection.  Slowly.  As it loses connection the resistance suddenly rapidly increases and that looks to the logic just like increased temperature.  But it's not increased temperature - it's a slow motion disconnection.

 

The problem is most likely right where the connector is.  Also it could be a trace on the board or it could be the sensor.

 

I'm an engineer - if you or someone you know is good with a multimeter you can fix it yourself pretty easily.  This is like a 20 minute fix for me.

 

I would take it all apart so you can get access to the tiny little PT100 chip (it's the only chip on the board - you can follow the traces visually that the smaller two wires go to over to that chip.

 

 I would first just reflow the solder at the PT100 chip and at the connector.  It's almost certainly the connector.  There is mechanical stress there when the board moves and several people have had problems on the forum with that connector not soldered well enough.  At least on the UM2.  Basically the UM3 is identical in this regard and I don't remember if anyone has had a problem with the UM3 connector but if they get what you describe it's probably the same spot - the connector.

 

99% chance this fixes it.  If not I would connect it back up and just hanging (not screwed in) and connect the larger two cables to a 24V 200Watt supply (not easy to find) and heat it up to 100C and while that is happening measure the resistance of the PT100.  It will slowly increase from 109 ohms at room temp to around 200 ohms when hot but then suddenly sky rocket to infinite ohms.  At that point you can probe each point along the path and find out where the failure is exactly.  It might be that you need to run two tiny wires from the connector over to the pt100.  In fact I'd just run those 2 wires if the reflow trick doesn't work and not even bother heating it.

 

OR you can get a new bed heater from your reseller.

 

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Thank you for such a comprehensive answer!

 

I read this wrong the first time and took apart the main board, looking for the PT100 chip. The good news is that all none of the joints there look dry.

 

After reassembling all that, I took a look at the proper location, and ran into what I imagine is a really stupid problem -- I honestly don't know how to disassemble it to a point where I can reflow the solder. Here's a photo of what I'm looking at -- pulling on the wires doesn't seem to remove them.

 

 

IMG_4898.jpg

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Do you have a multimeter?  Disconnect this cable at the *other* end underneath the printer and measure the resistance there.  It should be around 100 ohms.  If it's failing it should be well over 1000 ohms.  While one person holds the multimeter to the two wires, another person needs to push and poke at these connections.  Push quite hard - maybe 1kg force.  Hopefully, the resistance will jump from around 100 ohms to infinite.  when that happens you found the problem area.

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Alternatively, turn the printer on and go to SYSTEM and go to where you set the bed temperature and leave the temperature at 0C but have one person watch the temperature while the other person pokes at these connections.  The problem with this approach is that every time the temperature goes over 700C you will then probably have to reboot your printer and start over until you find the problem spot.

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I have error showing.

ERROR sensor BED

 

The problem is its is intermittent .

I have re-solder connecting block on bed.

Checked board connection .

Tested for O/S wires from board to bed.

I getting a reading of 109ohms resistor? on bed.

I can get one print (first of the day) , try to print again some times OK some times fault.

The printer has done several hundred hours

Is it the board or bed?

 

Ultimaker 2+

I upgraded to + months ago

 

thanks gromit

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