conny_g

And both transistors failed the transistor test in above linked post. Both had 0 Ohms Collector-Emitter. Did the repair, now curious if it's going to work. Not really a "beautiful" repair, but technically ok. :-)

I'd say that T1 has a hole :-)

So the front panel display/ wheel are unused after the mod? Do you need a different display then or just none?

I have already changed the Atmega16u2 on another board and the buck converter on this one. I think they are harder to change, so the bc817 should be easy. The black/blue box is a relay, afair it’s connected to the emergency switches that are shorted/jumpered/unused in the UM2. Good point actually that they are for 10A, hope they have a bit of tolerance as with my 360W power converter I need 15A ....

@neotko just ist watched your video on cabling the Duet3D board in the UM2. What firmware are you using? Marlin ported or another one? You then use the Duet display with, not the UM2 built in anymore? Cura works with it? What do you have to configure? As my UM2 board on my 2nd printer is broken (see other post) I am thinking about how large the Duet3D mod is in comparison to repairing the UM2 board... ;-)

Researching about it I find that @neotko killed these transistors a few times, so it seems to me they are in fact a weak point of the board. Thinking about what might have happened. The power adapter - the chinese one with 360W, not the original - might have significant output capacitance, maybe it even causes a voltage surge when plugging it in. So possibly it sent that surge across the board on the 24V „rail“, that would hit all components exposed and surely these BC817 and the step down. Then there is this damaged LED on the stripe, it could be dead due to that as well. Or the LED dying actually killed the transistor? But that would not explain why the step-down died. Wondering if that chinese power converter will kill my board more often. But on the other hand I am using the same model on my other printer for 1 year without issues... Anyway, some more fun to be had with dissassembling the printer and repairing the board another time the next days. Would just ignore the light for a while, but the model fan missing is fatal. Had a really bad print due to that today. That triggers the repair.

Hi, recently I plugged the power adapter into the board with the on/off switch at „on“. Heard some sizzling noise, then got some burnt smell, afterwards the printer was dead aside of some glowingof the LEDs. The step down converter on the board was burnt (had a hole in its case), part „U6“ not far from the Atmega16u2 that does the USB communication. It‘s a Allegro A4403 step-down converter, creates the 5V for the board from 24V. After replacing it the board generally works, but two issues are left: the LEDs are dim, only one segment is bright with one dead led. the model fan does not work. Both are PWM controlled outputs with a transistor, see linked thread where a similar thing happened. Not entirely sure if the LED output is damaged or if that dead LED causes the problem. Now my question: these outputs burning out, is this a common thing to happen? Anyone experienced this, too? I am looking for the reason why this happened. cheers, Conny

Yes, create a second profile with a standard UM2. Then you also get the complete build space. Don’t forget to remove the 2nd head in this mode. There’s a magnetic hanger STL for this. I have two printers running with this one: https://de.aliexpress.com/item/Top-Qualit-t-24-V-15A-3D-Prnter-Ultimaker2-Netzteil-F-r-Ultimaker-2-UM2-Erweiterte/32832288123.html?spm=a2g0s.9042311.0.0.ZrP37J 360W, all heaters running on full power, no issues with power anymore. Even exchanged the hotend heaters for 50W ones, they heat up lightning fast now. Don‘t know. But also have no need. After two years that’s routine and only need to do it every few months.

Ah, UMO, ok. I think I didn’t realize that late in the night that this was about UMO....

Working with UM2 for 2 years, haven’t ever noticed that menu time-out at all.

The UM2 heater is 25W, the UM2+ is 35W, so it takes some 50% longer to heat up. Here in the printer definition: https://github.com/foehnsturm/Mark2/blob/master/cura-resources/definitions/Mark2_for_Ultimaker2.def.json In „machine-start-code“ you could add a head temperature command at the beginning to preheat E2. https://fablabdigiscope.wordpress.com/list-of-raw-g-code-commands-for-ultimakers/ Use M104 and M109.

The key is: there is no "normal dual extruder" of the UM2. UM2 never supported dual extrusion, that's why the community projects as Mark2 and the watercooled thing (and others) have taken care of it. Haven't tried it or followed it more closely on the results in the community. But my guts tell me it work's as well and works fine, but for me the effort of the water cooling is more than it needs, I wouldn't want to deal with water cooling. But the overall effort is probably not too much worse in comparison. So try whatever you like better.

Identical settings, offset different. So it's pretty random. This drives me crazy. Any ideas what I could do or where to search for the cause?

Zoom photos of both sides, showing the X-direction effect. In the first marked where it begins and where it ends. The prime tower is positioned (direction-wise) as it was during the print. Interesting in this print that only part of the print is affected.

Interesting. This time it's coming and going across the print. The only thing I changed was the X/Y extruder offsets, I tuned the calibration by Y 0.1 and X 0.05. I'll reprint this with same settings and same g-code now to see if it mechanical or 100% repeated and thus software. Next time I will tune the offsets by 0.05 different, maybe on just one axis. I have the feeling that this 0.05mm rounding issue is not gone, maybe it's more complex than just setting an offset of multiples of 0.05.

Good to know there is others that have this issue! Currently trying to print the identical object with identical settings to see if the effect is identical. If it is one could see that as a hint that it's more a software issue than a mechanical issue. For mechanical I wouldn't know why it should be identical if the effect occurs due to some "random" event during the print.

Redid the extruder offset calibration and that was at max 0.05-0.1mm off, but probably just the remainder of the original calibration. So that seems rather unchanged.

Hi all, I keep having some offset between the two heads, see photo. Somewhere mid print the prime tower looks more white front and left than before. Which means silver moved more to the back. White is extruder 1, silver is extruder 2 (the docked one). I always had that and decided to redo the head and docking to make sure it's not that. Now that I have reprinted and remounted the new head with much care that the magnets sit perfect I still have that offset issue. Before I had it from the bottom (though calibration was ok every time), now it's starting halfway through the print. As the head / docking is now perfect it's not inaccuracy of the head, must be something else like step losses or something. To summarize the facts: measuring the prime tower lower half, higher half: it's 14.8mm in Y direction and 14.85 in X direction in the lower half. It's configured to be 15mm. In the upper half - after the offset occurs it's 15.2mm in Y direction and 15.1 in X direction. So the delta in size is 0.4mm in Y and 0.3mm in X. Difficult to measure, might have an error of some 0.1mm. The delta in size is the the changed offset of the heads it starts somewhere mid print. I can't think of any trigger in the STL model, I think it's random. What could be the reason? Theory: The docking process requires too much force and causes a step loss. Thoughts: A step loss would change the head position overall, it would not change the offset between the extruders. So it would cause a layer shift once and then E1 and E2 would stay in sync. Seems unlikely. Theory: There was this rounding issue in head offsets. Could special coordinates for the origin or the target before/after the docking process cause the rounding issue and result in an offset? Thoughts: Then the offset should change over time, it should sometimes appear, sometimes not. Or it should happen more often than just once. Seems unlikely. Theory: The Mark 2 tweak script, could that cause a change of extruder offset? Thoughts: it only removes moves, it does not change any ccordinates. Seems unlikely. Now I am out of ideas. One thing I could check is the coordinates in the g-code for the prime tower. If they are the same through alle layers, it's hardware or printer calculation. If it's visible in the g-code, it's something else. I wouldn't know a reason why the g-code would change. Checked it. Coordinates of the prime tower are the same across the file.

@foehnsturm, while reprinting and remounting my head for the gap issue (coupling is redone now, head is next) I discovered a possible weak-point of the coupling, depending on the resulting hole size of the coupling. If the screw is not a perfectly tight fit in the hole (tight fit: you need to screw the screw down, you can't push it down to the alu part) then the coupling can move by up to 0.25mm (whatever the inaccuracy of the hole might be) at the bottom very easily. On the top it less of an issue as the thumb screws press the coupling to the head there, it can't move there. I fixed it by applying two layers of 5x5mm duct tape to the coupler, above the hole, see red marking in the picture. That covers the 0.2-something mm of distance, now the screw sits tight in the hole. Possible fixes in the design: 1) duct tape 2) a small screw in the coupler from the front that presses against the head to avoid the movement. 3) some spring-like extension of the coupler 4) a notch of e.g. 0.3mm that needs to be filed down until carefully until the screw goes through tightly 5) a notch in the screw hole that the screw can easily handle that makes sure the hole is tighened down. Or an oval hole with one side tight, but low force to get the screw in. I think the notch in the screw hole or the oval hole could be the easiest if they survive multiple unmounts/remounts.

I have changed my coupler and since then it's better, but still the Green-Tec has a slight tendency to underextrusion. I need to increase the flow slightly to 105% to get nice results.

Try: http://3dsolex.com/author/cbbeckgmail-com/ (email encoded in that url... ;-) ) Carl is the owner of 3D Solex. It's a small company, even to info@ would likely be ok to reach Carl.

Try a factory reset of the printer. Somewhere in the menu.

You could also use a prime tower instead of the ooze shield. I prefer that. Alternatively you optimize the tool change retract settings to perfection, I think @foehnsturm is a master in that. :-)

@foehnsturm I think this might be interesting to include in the BOM of the Mark 2 upgrade: I am about to upgrade a former UM2 as well and it is possible to reuse the old head for Mark 2, so you need to buy only 1 upgrade kit for a UM2, not 2.

I had the same question to answer and I am reusing the UM2 head for my 2nd printer (that was formerly a UM2 as well). The old head and cable tree do work for the Mark 2 upgrade. The fans, connectors, elements are identical. The head parts are identical. The heater of UM2 is weaker (UM2 25W, UM2+ 35W), but it does work as well. There is one detail of the old head, there is a spring fixing the PTFE coupler, that should be changed into the aluminium ring. You can buy that as a spare part, I did that. And you should use a Olsson block instead of the old nozzle setup.