SyntaxTerror

Better late than never, I suppose? Sometimes questions begs more questions, and this is one of those times, I'm afraid. It's a straight UM2, not a 2+? Regardless, it would be best if you check which main board version you have. It'll say so in the silk screen on the component side of the PCB. Assuming it's a 2.1.1 and the printer is alive at least (you can make it do things), the hot end fan problem cannot be located on the board, as the 2.1.1 supplies constant +5V directly from the onboard power supply to the fan (except if we're talking copper / connector problems). If the fan isn't running and the problem is on the board, the entire printer would be dead as a hammer. Since you've replaced the hot end fan itself, I'm going to go ahead and assume there's a problem with the fan extender cable in the loom to the head. The model fans, on the other hand, is extremely likely to be board failure. Regardless of board revision, they're PWM controlled. I'll bet you just about anything that T1 is shorted collector-emitter. Thankfully, if you're handy with a soldering iron or know someone who is, you can get spare transistors thrown at you everywhere. It's a BC817. As you can see, they're certainly affordable enough and stock is never a problem. /mike

Ahh you're a star. Thanks so much! Funny how sometimes you just know you read something somewhere, but for the life of you it won't pop up no matter how much you google away. Then of course when you have the answer, the thread can be googled in 5 seconds flat.

Alrighty then, ye firmware geeks, amaze me: Can anyone tell me where the Z-offset between the print cores gets stored in the printer? I'm getting sick of leveling this thing until I'm blue in the face before it gets just right, so I'm looking for a manual edit option somewhere. Cheers 🙂

If it really IS solder, I have to wonder how on earth it got there. It really, really does look like solder that's been heated long enough to burn off all the flux. No matter. If we assume that whatever it is melts in the nozzle... it would be a reasonable assumption that you could get rid of it with some desoldering wick and either a soldering iron or a heat gun.

That's really odd. Looks just like solder.

Oh, this reminds me: Could you also please add the prefix of your power supply? Is it a GS or GST unit?

I think we need to start a data collection regarding power settings. Maybe when we have enough people with working settings, we can figure out something that is shutdown-safe for everyone.

No problem

Wait, what? I didn't get any PM?

Yep, that looks like the correct part. Good luck!

On a side note regarding sourcing of the part (shipping/administration costs and such), it's probably safe to say that due to the Mark 2 project I'm pretty damn well stocked on BC817's. If you want, I can throw a few in a letter and mail them to you.

For most SMD components with pins coming out sideways from the package, I'd always recommend cutting them with a scalpel rather than trying to desolder the entire part. Cut it out, then desoldering the individual pins is easy as can be. And yes, you'd need a relatively fine tipped soldering iron to work on the board, this is true. The switching transistor is designated T1, part number BC817, available here. Component location is:

Wouldn't it be better to just install a new switching transistor on the board? It's a 0.13 euro part and anyone familiar with a soldering iron can replace it in 60 seconds. Just saying.

Since we're talking abrasives I'm just going to throw one thing in there that's highly useful - especially to people not terribly proficient in sanding/polishing. Micro-mesh This is a great product. Small abrasive pads in a variety of grain sizes and you can buy sets that allow for easy sanding through the grits. More importantly, they've got a foam backing which ensures correct pressure by letting the grain sink into the foam in case too much force is applied. No need to wrap it around anything like you might want with sandpaper either, the foam is stiff enough to work on its own. Heh, incidentally they have their own grit scale too Fantastic bit of kit, this - nonstandard grit or not. Ranging from around 30 to < 3 microns - I've buffed out scratched watch lenses with it.

@Labern has a mirrored feeder assembly up on youmagine that works very well here.