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A fix for Ultimaker 2 heated bed not working

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Today the heated bed did not want to get hot.

There was no error but the bed never increased in temperature.

We have one of the few pre-production units, but I think the construction is the same for the production units (for example, there is a strain relief installed).

The root cause was that one of the cables has become loose in the heated bed connector.

It was pretty easy to fix it, but I did have to remove the glass and unscrew the levelling screws and the strain relief to access the heated bed connector.

Then after re-assembly of course a re-leveling of the platform. Now it works again :)

I wonder whether this would be a common thing to happen or not. Did it happen to anyone else yet?

Picture below.

UM2 loose cable causing No heating

 

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It's a problem with the early production series beds. There is a problem in the soldering of the connector. It's quite hard to solder yourself (as the bed works as a giant heat-sink)

If the problem persists, contact support, pretty sure the new beds do not have this issue anymore.

 

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Yes, had the same thing when my U2 arrived a few weeks back, it was printing fine for a while but it occasionally gave me a bed temp error while printing and I noticed that all 4 wires were very loose (they could just be lifted out, the main cable clip to the build plate was all that was usually keeping them in the socket). FWIW you seem to only get an error reported by the U2 if one of the two thinner temp sensor wires comes loose, if either of the thicker power cables is loose you just get a bed that wont heat up (you can still print in PLA, PLA-Flex by tuning the build plate temp setting to below ambient temp).

Unfortunately I had to open a support ticket today with what seems like a different build plate heat issue, here's a description of the issue if any one here has any ideas...

About a week ago I had the same issue as I now have again today, the build plate was reporting ambient room temp and not heating up. I checked and reseated all the build plate cables again, all seemed fine. I found the post on the forum that suggests opening up the controller underneath and checking the build plate cables haven't come loose from the main board, they seemed good as well. While I had the printer open and on its side I also checked continuity of the cables between the board and the build plate, they were all working. After sitting the printer back upright, without finding any faults, I booted the U2 back-up and retested a print to discover the build plate was heating up correctly again (intermittent faults are the worse)!

 

The U2 had been working well all week since then, lot's of successful prints, until today. I've repeated all the above without luck. Some extra checks today:

 

- I've tested the resistance of the build plate heat circuit when disconnected, it's 6 ohms (that seems lower than I would expect, but I can't find any documented reference as to what it should be)

 

- When the build plate power cables are disconnected (but sensor wires connected) I've measured the voltage across the build plate power cables when the U2 is set to heat the plate to 50C, it seems to report a correctly looking voltage of ~23V

 

- If the build plate power cables are connected to the build plate, the voltage drops close to 0V, as if it can't power that load

 

- I had another visual inspection of the board underneath the U2 but can not see anything that looks unhappy.

 

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Does the nozzle heat up okay during this? Double check that please - if nozzle also has trouble then the problem is likely K1. Give it a hard tap.

Otherwise it could be a bad connection anywhere in the cable where it isn't quite connected somewhere but connected just enough to supply a tiny bit of current. You should jiggle the wiring all along the path. It could be at the PCB itself. If jiggling the wire doesn't fix it you could tell UM you need a new PCB.

Personally though I would diagnose further. Look at the pins on the mosfet. Make sure the signal from the arduino is turning the mosfet on and look at the signal across the mosfet pins when the heater is connected and not connected. Also there could be a bad solder joint so I would just heat up the 4 or so solder joints related to this.

 

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Thanks gr5!

So, yes the nozzle is heating up just fine, I've printed a couple of PLA-Flex prints today at 230C on a cold bed and they came out great.

Are you aware of any official/unofficial circuit documentation or labeled photos kicking about? Anybody made a U2 hardware tear down yet and posted to youtube? :) I'll take another pass at manipulating the wiring along the path and reseating and retesting the cable at both ends (it seemed to work once before, perhaps I'll get lucky). I'll also check the PCB solder joints on the back of the build plate connector (found a forum post about bad solder joints there on some early U2 builds).

I'll give support a little more time to respond in case they have something specific to test before I start to digging too much deeper, but I might take a closer look at the board when I'm going back over the cable/connector check and have the base open again. Thanks for the hints.

 

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I've managed to get the heated bed working again this afternoon after closer inspection of the cables on the motherboard. The issue appears to be the socket for the heater bed, part of the green screw terminal on the main board. The screw terminal for the brown power lead from the bed shows some signs of excessive heat, it is a little blackened inside and heated enough that the metal inside of the terminal (part that cables the clamp) is jammed due to some plastic deformation inside the terminal (it is 60% closed, turning the screw doesn't open/close it), the end of the brown lead was a little sooty, and darkened. After rechecking continuity on the build plate leads (all were good), I cleaned up the end of the brown lead, applied flux, and some fresh solder to the end and re-inserted it into the 60% clamp gap. It was a tight push fit. I measure 0ohms resistance between the motherboard pcb and the heated bed pcb. Retesting now shows the heated bed is working correctly. :)

 

My worry is this is only a temporary solution as the screw terminal for the brown socket is not properly clamps the lead. It's also unclear why the brown lead terminal should have gotten hot enough to damage the terminal plastic (maybe the original terminal connection was poor and the higher resistance there caused excess heat or some electrical arcing).

 

Longer term fix options would seem to be:

 

1) De-soldering the green screw terminal from the mother board and soldering in a fresh replacement. I'm not sure if my soldering iron is a high enough wattage for all that copper, but I could perhaps do this at the local Hacklab where the equipment is a little more heavy duty.

 

2) Swap out the motherboard pcb with a replacement.

 

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Not enough voltage for arcing. But if the resistance was between .1 ohm and 1 ohm due to not clamped down on the wiring then that will cause a lot of heat.

Your current fix is probably permanent. But if not, you can ask ultimaker for another pcb. Contact support.ultimaker.com. You should probaby do this before 3 months from when it was shipped. If it was me I wouldn't worry about it and if it happens again I would just fix it myself.

 

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Hello,

I am having the same problem with the chard connector seemingly due to loose connection of heated bed - had machine for just under 7 months printing well off and on for most of the time. I would like to try to fix without replacing the PCB as UM support and getting parts has been not so speedy in past (sadly) - have open support ticket that has not yet been assigned.

Can anyone give guidance on whether the soldering of a new connector went well? Anything I should be aware of prior to going down this path? Any specific part numbers? Any issue with soldering directly to the PCB (haven't removed the connector so not sure if that is possible).

I have the machine torn apart and am at the point of unsoldering the connector and acquiring a new one - going to look around to find part number - if anyone can verify the replacement part number or know of where to get one fast in the US that guidance and help would be greatly appreciated. I am not extremely experienced with soldering but willing to give it a shot to fix my machine.

Thanks,

Ben

 

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More information please. Which error? Do you really expect us to read through 16 posts because you were too lazy to type the error? There are several errors:

HEATER ERROR is one of the new ones. There is an error that mentions "BED" and another one that doesn't. There are at least 3 possible errors that I know of.

There are 4 wires going to the bed. Two measure temperature. Two supply power to the heater. Either of these two systems can break but the symptoms are very different. If the temperature is working then you get the correct temperature even if it won't heat up (typically rooms are around 20C).

 

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sometimes the bet gets a bit warm, sometimes it stays cold

 

If it stays cold but the temp is reading > 30C then it's the temp sensor you need to concentrate on.

All of the possible error conditions are easy to diagnose and fix so we can walk you through it with more information. This is like batteries and bulbs. Not computer science.

 

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This is just for other's future reference.

I've had my Ultimaker 2 for a little over a year.

The heated bed suddenly stopped working. After checking the output at the motherboard (24V) and at the heatbed connector, I turned the bed over and when I measured at the solder pads, there was a little arc, and it started working.

I resoldered the bed, and all is well now.

 

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Hi all,

I'm stuck with the Heated bed error.

Firmware v.15.02.1

This seems to be a relatively widespread on the Ultimaker 2 as far as I've read around.

I've already opened a support request (ticket n. RLY-342-1920)

I've also uploaded a couple of videos:

https://youtu.be/u6lDR2Q4ca4

https://youtu.be/HUYlk2R7vTQ

I'm not able to fix it by my self, so I would ask:

- Is this problem under warranty? If yes, how can I claim it?

- Is there anything I could try to inspect and fix this problem?

My machine is unusable right now ...

Thanks in advance for any help

--

Christian

 

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Hi,

before I'm gonna open the Ultimaker 2. What is the problem with the Ultimaker 2?

- Ultimaker was printing with heated bed but a second print the heated bed was cold.

- With the second print the sensor stated: 90C/60C but with an cold bed

- Now when I turned off the Ultimaker 2 for a while the sensor stated in the Maintenance/Advanced/Heatup Buildplate: 85C/0C and still the bed is cold.

What is the issue in my case?

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before I'm gonna open the Ultimaker 2. What is the problem with the Ultimaker 2?

 

I don't think you mean "open".  I'm not sure what you are saying.

 

- Ultimaker was printing with heated bed but a second print the heated bed was cold.

- With the second print the sensor stated: 90C/60C but with an cold bed

- Now when I turned off the Ultimaker 2 for a while the sensor stated in the Maintenance/Advanced/Heatup Buildplate: 85C/0C and still the bed is cold.

What is the issue in my case?

 

The temperature sensor is called a PT100 both for the nozzle and for the print bed.  For this device, the higher the resistance the higher the temperature.  Well when you have a wire or an electrical connection partly failing you ALSO have a higher resistance.  That is what is happening in your case.

There are several things you can check real quick without sending your printing back.  First look at the thick cable that connects to the heated bed in the rear left corner.  There are 4 wires.  The thick wires are for the heater but you are concerned with the 2 thin wires - those are connected to the PT100 sensor.  Make sure the screws are tight and those 2 thin wires are not loose.  You may have to remove the upper bed to get to it - not sure but it's easy if you need to.  The aluminum plate is removed by ONLY removing the 3 leveling screws.  Remove glass first of course.

The second thing to check is underneath the printer.  Remove the larger of the 2 covers.  It is held on by only 2 screws.  Push up the bed before accessing the screw heads.  Everything is labelled.  The first "TEMP" is for the nozzle.  The 3rd TEMP sensor is for the bed.  Check those wires.  If this all seems fine you should contact support.ultimaker.com and they will send you a new bed.

Edited by Guest

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