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UM2 problems

Posted: May 25th, 2018, 2:52 pm
by Izzy
Hi guys,
I wanted to check the hive mind.
My UM2 is playing up, the y axis is stepping off, originally I was thinking it was the stepper motor as I had one previously that began to seize and would mis step, but got some new replacements as my reconditioned one with new bearings was doing the same, but problem still there.
I then thought it way be the belts were getting slack, as a quick fix I fitted a little belt tensioner, but still the occasional problem.
Not only that but occasionally the Y axis motor will stop, head won’t home or move, switch off and back on and sometime it works but will after a period of time stop working, checked with spare motors just plug in and intermittent function.
Is my main controller board dying on me and needs replacement, and if so any recommendations as to where from?
Cheers, Izzy

Re: UM2 problems

Posted: May 26th, 2018, 3:02 pm
by shurik
Reading the description provided, the main board comes as the suspect on my mind.
Could that be some wires getting occasionally loose?

Re: UM2 problems

Posted: May 26th, 2018, 4:18 pm
by Izzy
Cheers Shurik,
I think it could be possibly be a dry joint, the reason is that from being off over night it will successfully print a UM Robot or two with no problems, then the Y motor might skip a beat, I thought it might be the belt slipping as that’s what it sounds like but I’ve just added some belt tensioners as an interim until I get new belts.
It will work for a while and the then skip, but when I go to rehome the head the Y motor has stopped, if it was just the belt slipping or skipping then it should just move, so I do think it’s a problem on the board, but my UM2 is 3.5 years old and done a fair bit of printing.
The thing now is to get a cost, and see the difference between a UM supplied on or, I hate to say it a eBay one from China, in the U.K. a V2.1.4 motherboard is about £130, but a China one is about £80, it’s tempting to get from China but I’m dubious about its quality etc.
I will likely get in the U.K. from a reliable ultimaker source and replace the belts too, just wish I didn’t have to strip down the shafts to replace the belts.

Re: UM2 problems

Posted: May 27th, 2018, 8:09 pm
by LePaul
Ah that board seems fine?

Re: UM2 problems

Posted: May 29th, 2018, 4:27 am
by Izzy
No I think it’s a board problem, possibly a dry joint connection, but I don’t really have the time or expertise to find it at the moment so will buy anew one and then when I have time see if I can locate the problem on the old board.

Re: UM2 problems

Posted: May 29th, 2018, 7:10 am
by shurik
I bought my replacement board on Aliexpress for about 1/3 of what our local distributors wanted.
Works fine so far.

Re: UM2 problems

Posted: May 30th, 2018, 12:45 am
by nilrog
It is probably one of the stepper drivers, or it's joints, that is starting to give in due to heat and time.
What you could do if it is only the Y-axis that is acting weird is to change it to use the 5th unused driver on the board.

The fact that they (UM) have mounted them without any heat sinks or fans will cause them to degrade over time. Unless you have the printer somewhere where it is not so hot.

On the UMO+, which is a "tinkerer" kind of printer it is ok to have the board "bare" as they do. Those who buys that printer are more likely to fix that themselfs. But not mounting any additional cooling on the board in the UM2 which was sold as "plug-and-play", and "high-end", was a bad choice i,o. Yes, the drivers can stand the heat without that extra cooling. But there is little to no margins...which is what you would like to see in a "high-end" device.

As to where to buy the board...going for UM will definately give you good a higher would also get warranty in case something happens. But you would probably loose the 5th unused driver since they started to remove that driver chip.

Buying from China is cheap(er) and you could be lucky and get a board that lasts for could also get a bad board. They are not known for excellent quality control. There is also a v2.1.5 board that the Chinese sells now where the drivers are in sockets so that you could replace them...even with TMC' make the printer quieter...and get rid of the zebra's.

Or you dive deep into the "modern" world like @Neotko (and soon me) and switch to a Duet3D ;)