We heard a pop and saw smoke, so we removed the back and fan, and we found a cooked chip. Does anybody know what this chip above C28 and U6 does, and what we need to do about it? See attachment. Thank you!
Michael
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That is a DRV8876PWPR motor driver chip which drives the motor on the bottom right arm. You can swap it out for a new one, but it’s probably easier to replace the controller board.
What was happening when it popped? They’re pretty durable chips (but not invincible)
Did it have a heat sink on it?
Not very much was happening. It didn’t look like what I would expect to blow a chip. One of my students lifted the power cable to the router (the router was not plugged in) to pull it out of the way of the other cables, and that’s when the pop happened.
If that were enough to cause a pop, then there must be some other problem, because I don’t think any kind of plywood cuts could be made without similar jostlings.
We didn’t alter the controller board in any way. We didn’t add or remove any heat sinks. Is there an easy way for me to recognize, from the photo, if it has a heat sink on it?
MRay wrote:
We didn’t alter the controller board in any way. We didn’t add or remove any
heat sinks. Is there an easy way for me to recognize, from the photo, if it
has a heat sink on it?
chunk of aluminum with fins on it stuck on top of the chips.
David Lang
Oh, well then no. If you look at the photo, you can just see the bubbled, burned black surface there. Should I apply heat sinks to the remaining chips?
Maybe I should add that this is in the Carpentry lab, and it could be a dusty environment. Is that a potential issue?
All the driver chips should have had heatsinks. On the earlier versions they were supplied as part of the kit but you had to stick them on. On later versions they should have been on when you received the board. If you have been running without, I suggest replacing the board as the other chips would have been stressed as well, rather than replacing the chip. Removing and replacing chips is not for the inexperienced.
Can you supply a photo of the whole board?
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Yes, I will get a picture of it this morning or afternoon, if I can, and post that here. Thank you for your input.
see this thread on heatsinks
Definitely no heatsinks mounted on these chips. They are important to carry heat away from the chip and dissipate heat to the air.
OK, thank y’all. Can I order another board on the Maslow site?
Ah this is a 4.0 board. We made quite a bit of improvements since then and we only have the 4.1 boards on our site now, but I can find a 4.0 board to send to you if you don’t want to deal with doing the whole upgrade.
DM me your address and I’ll get a new one in the mail tomorrow.
Thank you, Bar. I DMed you.
One other consideration. The Carpentry teacher who is collaborating on this project with my class (and who knows more about electronics than I do) said that he didn’t think that overheating was the problem with the chip that fried. The machine was not under load at the time. We were just plugging it in for the first time. And there was a jostling of power cables (not violent; just a slight movement; a student lifted the unplugged power cable to the router, that, itself, lifted one of the position motor cables, thereby taking weight off of it) that resulted in an audible pop and immediate smoke. Does this seem more like an electrical short than an overheating situation?
I recall having to move the heat sinks over from my 4.0 board to the 4.1 during the upgrade (which also had no heat sinks on the motor drivers). Either way, the Maslow has been able to operate in temps over 95 using my outdoor setup. It is a covered area, not in direct central Texas sun.
yes, and not just a matter of the motor being shorted, but of some other wouce
of power contacting a motor pin
a note on the 4.0 boards, the ethernet cables as sensor cables turned out to be
a bad idea. dust gets in them and vibration makes them lose contact. liberal
application of hot glue to make sure that the cables stay in place and no
sawdust gets in to the connectors is a really good idea. There is also a bug
with the sensors where a pin is not grounded and with just the wrong static
buildup, the sensor can start up reading backwards. A touch of solder as per
this image to ground a pin can solve this
David Lang
Thank you, @dlang! Would the hot glue and soldering techniques be obviated by upgrading to the 4.1 arrangement? I would like to upgrade to the 4.1 system.