MakerGear Forum

I'm hoping someone can give me some clues for figuring out what has happened. I will be submitting a support request, but thought I'd try here too.

I have a pre-assembled 12V/19V M2 from June of 2013. It has be working great ever since I got it and has been incredibly reliable.

Suddenly upon startup, the two 40mm fans (extruder and electronics case) no longer fire up. I can't get the 50mm bed fan to respond to M108 S255 and nothing happens with M106 S255 for the 40mm fans. The jog commands and bed heater work properly, but the extruder heater does not.

Here's what I've done to isolate the problem so far:

• Confirmed that each fan works when connected to an external 12V source
  Checked all the wiring connectors for tightness and/or damage
  Verified that the Dell brick 12V power supply is putting out 12V
  Tested continuity from RAMBo connections up to the top to check for broken wires. Also wiggled wires to test for intermittent issues.
  Checked the 15A automotive fuse
  Re-uploaded the firmware

I am getting 12V into the electronics case, but at the fan terminals in the case, there is no voltage, and none at the fan end of things either.

The only thing that has changed recently is that I had a second 40mm 12v fan connected in parallel to the extruder fan for about a week. Could this have caused an issue and fried my RAMBo? I know adding it in series would alter voltage, but thought parallel was harmless.

Any ideas are appreciated.

the first thing that pops into my head to check would be the nano fuses. there are 2 i believe on the rambo bard. they are little white rectangle fuses that sit in a holder. im not sure what they are protecting, the mosfets i believe but im just guessing. make sure those are ok.

Dammit Jim - it's dead! (I have been waiting a long time to use that reference!)

I had no idea those nano fuses were there. Sure enough, one had infinite resistance, and when I swapped the two, the fans fired right up! I didn't test the other functionality for fear of blowing something else up, but that appears to be the source of the problem. Now I just need to find where to get a replacement, hopefully locally so I can get back up and running ASAP.

Do you think the extra fan wired in parallel caused the issue or did I maybe just short it out somehow while I was messing with the wiring? "Dammit Jim, I'm a doctor, not an electrical engineer!" (Not really but I wanted to use that reference too)

Thanks for the insight!
Steve

I can pretty much guarantee you wont find those fuses locally. You have to get them from newark or makergear. Something probably happened when you were messing with wiring.

jimc wrote:I can pretty much guarantee you wont find those fuses locally. You have to get them from newark or makergear. Something probably happened when you were messing with wiring.

That would be my guess as well. Usually best to power down and leave down for a few seconds for capacitors to discharge before dinking with wiring with conductive tools. Lucky for you the fuse did its job quickly and efficiently. In my experience, usually the expensive, hard-to-unsolder semiconductors blow and protect the <$1 replaceable fuse.

And, I believe the correct quote is (approximately): "Dammit, Jim, I'm a surgeon, not a bricklayer!" (while standing over the injured mother Horta, a silicon-based life form). (Note that they used the correct "silicon", for the element, rather than "silicone", for the polymer, in the script. Good research. Most folks get it wrong.)

IIRC, Kirk replies: "You're a healer. There's your patient." Or something resembling that. I usually like to follow that with a mash quote, pulling in Kip Adotta's "Wet Dream" and add: "Fix the damn thing and leave my private life out of it, okay pal?" If you're old enough to get THAT reference, your M2 was a mid-life crisis buy or a retirement gift, right?

Speaking of old, Dale did you stroke out halfway through your answer and go on some unrelated rambling diatribe?

Lmao!!!'

Dale Reed wrote:
And, I believe the correct quote is (approximately): "Dammit, Jim, I'm a surgeon, not a bricklayer!" (while standing over the injured mother Horta, a silicon-based life form). (Note that they used the correct "silicon", for the element, rather than "silicone", for the polymer, in the script. Good research. Most folks get it wrong.)

IIRC, Kirk replies: "You're a healer. There's your patient." Or something resembling that. I usually like to follow that with a mash quote, pulling in Kip Adotta's "Wet Dream" and add: "Fix the damn thing and leave my private life out of it, okay pal?" If you're old enough to get THAT reference, your M2 was a mid-life crisis buy or a retirement gift, right?

Not only understood every reference - thoroughly enjoyed them! (And the McGuyver way that Bones dove right into the repair with cement - classic!) Still can't beat the Tribbles though - "Would somebody please shut that door?" - definitely the best of the best. (Do have to admit that I caught those in re-runs though. Not quite retirement age yet.)

But ignoring tribbles and Klingons and silicon-based life forms for the moment, back to the original question. . .

Did you overload the power supply by hooking a 12V fan in parallel with the extruder and electronics fans? No, probably not. In fact, it's a safer bet than messing with the two fans in series in the 24V power supply setup, which is an iffy case at best, relying on both fans to have the same resistance and be under the same load, which is almost certainly not the case at startup. 12V fans in parallel on a 12V power supply is pretty straightforward. The blown fuse was probably due to an accidental short, as you suggested.

insta wrote:Speaking of old, Dale did you stroke out halfway through your answer and go on some unrelated rambling diatribe?

Yeah, my apologies. Just picky about sci-fi movie quotes, I guess. Thanks to TBBT, I've been letting my inner Sheldon loose, and I keep forgetting when to turn it off. My bad. (And, yes, I watched Star Trek when it originally aired, and reruns ever since. I'm THAT old.)

Returning your thread to its original (blown nano-fuse) topic in 5 --- 4 --- 3 --- 2 --- 1 ---GO:

Turn off your M2 before aiming tools at it! I have a bunch of partially-bladed 40mm and 50mm fans to remind me...