UMO Heated Print Bed doesn't stop heating

[onkelgeorg 36]

Hi all,

tonight the printbed (or more likely the electronics) of my UMO seems to have died, after working properly for approx 7 months.

As soon as the printer is connected to the power supply the print bed starts heating. The red LED on the small PCB which came with the upgrade kit is lit permanently. So it seems that the power output is permanently fired. And after a few moments it starts to smell like burnt electronics.

How can I check which part of the electronics is damaged? Is it the small PCB or the main electronics board?

Any help is highly appreciated.

Cheers,

Joerg

[SandervG 1,521]

You don't see any visual markings on the board?

Unfortunately, electronics are not my field of expertise so I am not comfortable about giving you advice. But in theory, can't you use the other heating terminal on the main board, to test if that makes a difference? You would need to tweak that in the firmware too.

[onkelgeorg 36]

Hi Sander,

thanks for your reply. Sounds good, will check it.

[onkelgeorg 36]

Hi Sander,

here is an older thread which describes cause and effect perfectly:

https://ultimaker.com/en/community/view/8974-heated-bed-short-circuit

I think that's it.

[SandervG 1,521]

Let me verify that theory with our pro-team.

[SandervG 1,521]

What I understand that it is possible, but only for upgrades Ultimaker Originals.

That is because they have different electronics and the PSU is not connected to the main electronics but the smaller heated bed board.

If you turn the printer off while the heaters are still activated there is a chance power is still being guided to the bed, which can fry the component on the board for the heated bed.

It is important to note this will not always happen, it is also not suppose to happen, but it can happen. Advised is to 'Cool down' your heated bed in your UltiController before you turn off your Ultimaker Original. It could also have another reason, but this would be the most obvious. (especially considering the other post).

If you get in touch with iGo3D we'll sort you out with a new board

Edited September 18, 2015 by Guest

[onkelgeorg 36]

Hi Sander,

thanks for the detailed explanation. Now I entirely understand what happened and how to avoid this problem in future.

I already contacted igo3d and they sorted it out very fast and professional (will send you a PM)

[onkelgeorg 36]

ooops, almost forgot to finish this story.

As I didn't liked the idea to throw away the entire PCB just because of a dies MOSFET I asked a workmate to repair it. As we couldn't find the original one for a reasonable price, we had to find a substitution. What we found is this one: IRF 7832

Direct Link: http://tinyurl.com/hdlnsbk

The rest was not a big deal:

Before:

After:

So we got the PCB running again for 91 Euro-Cents and 5 Minutes of work. It is installed for approx. 3 months and works like a charm without any flaws.

May be this is helpful for somebody in future...