SKR-2
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bigtreetech
Conceptional design bug
About me, a buddy gave me a CTC 13A (Ender 3 clone) for free. That's how I got to the 3D print stuff and I'm an absolute beginner but I know a bit about electronic circuits.
I bought the board on Ebay, because I wanted a 3D board with more flash than my Anet 3D board has and a 32bit µC. Just started reading about the board, when I won the auction.
I read about blown stepper drivers. Read, it should be solved with REV B. I didn't understand the fix, they just replaced Q1 with another MOSFET.
Then I stumbled over this https://github.com/bigtreetech/SKR-2/issues/63#issuecomment-933762958. fitch22 explains the problem very well.
Reading more issues here, I read about some strange HW behaviour in connection with stepper drivers. I'm pretty sure it's this design bug, error, or whatever you may call it in connection with DISABLE_DRIVER_SAFE_POWER_PROTECT. But even without using DISABLE_DRIVER_SAFE_POWER_PROTECT, what will happen if this pin toggles a little bit (whatever the reason)?
I recommend to every owner of a SKR 2 to remove Q1 and connect drain and source pins!
I just connected the pins with a chunk of solder.
You may also watch this https://youtu.be/OH-h1Xz2V8g
https://www.reddit.com/r/BIGTREETECH/comments/s3c2q6/comment/hsrv9r8/?utm_source=share&utm_medium=web2x&context=3
@berkin88 DISABLE_DRIVER_SAFE_POWER_PROTECT kullandınız mı?
yes i did but it didn't work it still burns
yes i did but it didn't work it still burns
Of course it will fry. Did you understand the explanation from fitch22 https://github.com/bigtreetech/SKR-2/issues/63#issuecomment-933762958 electrically for the problem? Don't use "DISABLE_DRIVER_SAFE_POWER_PROTECT"! To be safe, connect "MGND" and "PGND"!
I'm curious if this is what killed my SKR2 board. When I first installed my board it worked okay and I was able to move some steppers, but the next time I restarted I got All High then after another restart All Low. Then the board died altogether. I found the 3.3v regulator died. I bypassed it with another regulator which quickly got hot along with the STM32. I bought a replacement board and all new drivers but I don't want to have a repeat failure.
I don't want to have a repeat failure.
"Then I stumbled over this https://github.com/bigtreetech/SKR-2/issues/63#issuecomment-933762958. fitch22 explains the problem very well."
Do you have "deep" electrical knowledge or is there a needing to explain the problem in a more easier way?
No, fitch22's explanation was good. I installed a jumper on my replacement board and so far it's been working okay. I asked on Discord if when we compile firmware for the SKR 2 board we should get a warning regardless of whether it is a rev a or b board. I haven't gotten a response yet but I think it would be prudent to do so. It would have saved my first board and drivers if I had seen that during compilation.
Discord
I don't know what you mean by "Discord".
I installed a jumper on my replacement board
Where?
get a warning regardless of whether it is a rev a or b board
Doesn't matter. It is a "Conceptional design bug".
Discord
I don't know what you mean by "Discord".
I'm on the Marlin firmware Discord server where devs can talk without necessarily doing so directly on GitHub.
I installed a jumper on my replacement board
Where?
From the board power supply negative to the ground pins on the CLS headers (pin3 on each one). The video I watched said to jump at least two which is what I did. That ties MGND to PGND.
get a warning regardless of whether it is a rev a or b board
Doesn't matter. It is a "Conceptional design bug".
Agreed, but for users that just got that board and do not know anything about it, it'd be good to get a heads up. I never knew there was an inherent design flaw until I had already trashed a board. I didn't shop for my board. Biqu sent it to me directly to replace a ver 1.4 board that had died.
I'm on the Marlin firmware Discord server where devs can talk without necessarily doing so directly on GitHub.
Thanks, I didn't know that.
From the board power supply negative to the ground pins on the CLS headers (pin3 on each one). The video I watched said to jump at least two which is what I did. That ties MGND to PGND.
Did you do that before you powered up for the first time with all the drivers and other stuff connected?
From the board power supply negative to the ground pins on the CLS headers (pin3 on each one). The video I watched said to jump at least two which is what I did. That ties MGND to PGND.
Did you do that before you powered up for the first time with all the drivers and other stuff connected?
Yep. I got it all wired up with the jumper in place prior to flashing the firmware and running it for the first time.