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Broken PWM on Ultiboard v2

Posted: December 16th, 2017, 7:54 pm
by nicoco007
I've been working with a few Ultimaker 2+ printers lately and I just noticed that it is impossible to change the brightness of the LEDs and/or control the side cooling fans on some of them. I know that on one of the printers the LEDs were shorted before this issue appeared, and on another one the fans were shorted, so I'm guessing something on the board was fried. This was confirmed when I swapped the broken board for one from a working machine, and both the fans and the LEDs worked.

I did a bit of research, and it looks like it is most likely the PWM circuit's transistor that was fried on these boards. According to this document (page 8, bottom left corner), those are BC817 transistors. However, I have looked at them on the boards in question and they don't seem to be damaged in any way.

Would it make sense to replace these transistors, or is this issue caused by something else altogether? We'd rather not spend hundreds of dollars on new boards if it's just a tiny part of the board that is broken.

Re: Broken PWM on Ultiboard v2

Posted: December 17th, 2017, 9:08 am
by Neotko
I broke my bc817 8 times, first time I did pay a professional to change the transistor. But the sexond to 8th time I did it learning how to solder stuff and with kapton tape, air desolder and patience.

https://ultimaker.com/en/community/1721 ... not-solved

Re: Broken PWM on Ultiboard v2

Posted: December 17th, 2017, 4:23 pm
by nicoco007
I took a look at that thread and attempted swapping one of the broken transistors with one from a board I knew was good, and it worked! Thanks!

I decided to buy a bunch of them off DigiKey; hopefully they'll work. I'll post an update once I receive them.

Re: Broken PWM on Ultiboard v2

Posted: December 18th, 2017, 3:13 am
by jonnybischof
Yup, those transistors have 0 chance of surviving a short circuit :)
Fine example of "maker electronics".

Re: Broken PWM on Ultiboard v2

Posted: December 21st, 2017, 7:03 pm
by nicoco007
jonnybischof wrote: December 18th, 2017, 3:13 am Yup, those transistors have 0 chance of surviving a short circuit :)
Fine example of "maker electronics".
Yep. Just replaced all of them and they work. It's a bit annoying that this happens considering the fans are one of the easiest things to short circuit...

Anyway, for anyone living in Canada or the US, I can confirm that these transistors from DigiKey work perfectly.

Thanks for your help guys!