Heated bed short circuit?

[kouvadaki 0]

So, I have searched the forums but did not find anything similar.

I have installed the heated bed kit to my Ultimaker original and printed a few parts with success. However today I tried printing something but noticed that the filament was not moving. So, I pushed "Cancel print" in cura and waited for the temperature to drop to remove the part from the bed. The temperature was keeping steady, so I turned off the Ultimaker from the switch.

And here is the problem. I immediately smelled something burning and the temperature of the heated bed started climbing! I unplugged the power supply, turned the thing over and noticed that the IC in the pic gets extremely hot as soon as I connect the hot bed connector...

http://umforum.ultimaker.com/index.php?/gallery/image/9828-img-20141025-185801-s/

It does not matter if the Ultimaker is idle or ready print, as soon as I connect the plug the IC gets HOT and the bed starts heating up. If I keep the hot bed plug out of the connector then the printer is printing OK.

Is my hot bed fried? It lasted only for 5 or six prints...

 

[arnienz 0]

Yes same problem today. Something has failed on the control board and the heated bed is full on permanently. Lucky I noticed it or there could have been a serious melt down!

I have sent a support request. Suggest you do the same.

Regards

 

[kouvadaki 0]

Yikes! I was almost certain what had happened to me was a faulty board, but since it has happened to someone else, perhaps it should be more clear to the heated bed upgrade kit users that there is a way to damage their board!

So, when you are printing with the heated bed on, DO NOT use the power off button of your Ultimaker. Doing so might fry the output stage of the hot bed electronics, since the power switch will cut off power to the original control electronics and not to the add on board.

Why would you want to flick the power switch? Well in my case the feeder started losing grip, and I stopped the print. However, the temp was still high and Cura does not release the Z motor when you cancel a print, so I could not lower the bed by hand (with the old Z coupler, even with the stepper on I could turn the screw, but not with new one...).

 

[kouvadaki 0]

Update: After discussing with support, they will send me a new heated bed PCB, as it seems my old one is dead (there is always 24V at the heated bed connector).

Now, does anyone have a suggestion as to how I can stop / cancel a print in the middle? The PCB was fried when I switched off the printer during printing. Is this a fluke or has it happened to anyone else besides me and arnie?

 

[zungara 10]

I do not switch off the printer abourting a print. I use the stop printing function.

 

[kouvadaki 0]

I do not switch off the printer abourting a print. I use the stop printing function.

 

Before i installed the heated bed upgrade kit, I too stopped with the cancel function... But after the upgrade, I noticed that the cancel button in Cura stops only the nozzle heater, and the hotbed remains on. How do you stop the hotbed?

 

[fluxline 0]

you could always use downloaded pronterface, not the one supplied, and a use the the buttons there to turn off motors and heaters.

 

[andrea-bakker 0]

Hey Kouvadaki,

Exactly the same problem here.. Same cause.

 

[kouvadaki 0]

I have received the replacement PCB from Ultimaker support and will post back as soon as it is installed. Also, I will check for the pronterface interface options (currently no at home with printer).

However, I think the cancel button in Cura should stop the heating anyway. Perhaps I should post a bug report in the Cura forums...

 

[arne 0]

Maybe put a switch between the power supply-adaptor and the Ultimaker?

 

[fluxline 0]

just to update, this not only happens with switching off the power supply. started a new print and after 5 minutes the printer just stopped, not sure why. after that the heated bed would not shut off and the temp just kept rising.

responding to this thread jinxed me!

 

[mehmet-fatih-sevik 0]

Hi. I have same problem too.

Is there anyone can write whole name of this electronic component (i cant read mine its now black )maybe i can find and solder it...

 

[psyberjock 0]

I was just looking for a replacement chip. I'm pretty sure this is the correct chip. IRF8736

Here's a link to a good place to buy them on Aliexpress. I'm not connected to this company, they just have the best delivery times and price per piece. I bought 10 chips for slightly over $7.

http://www.aliexpress.com/item/IC-IRF8736-F8736-IR-SOP-18-A-30-V-0-0048-ohm-N-CHANNEL-Si-POWER/1183938546.html

[markotime 0]

12v bed, shorted, resistance measurements indicated that the 24vdc connections to the bed would work after a fashion, providing approximately 60 Watts, rather than the original 75.  Eventually heats to over 55C, insulation may help that, and

will attempt to raise power supply voltage to 13V or maybe a bit higher.  Power = V2xR (V2 is Voltage squared), so raising

voltage by 10 percent would do the job.  I'm assuming that the voltage regulator on the control board will handle this.