My Smoothieboard has been a rock star since day one. I think we are on day 365+. Until last week I’ve been using a standard computer fan for PLA cooling controlled by the mosfet at pin 2.6. This has worked without issue. However, the performance of those types of fans are not very good so I decided to switch to a ducted fan. This was working great until yesterday. The fan will not turn off. I have tried re-setting the board and it just will not turn off. The LED for that pin is on and the fan is powered up. I have tried M107 and M106 S0 to no avail.
When a mosfet fails, does it fail in a closed state? Will it damage the board if I leave this as is and just switch the fan to a different pin?
Imported from wikidot
Mosfets die either in a closed or an open state. Most frequent is closed I believe.
Did you install a diode on your mosfet ?
No, I did not. And I only recently discovered that as a recommendation. Is this something that will be automatically included in future boards? Seems like it should be.
It will be included in the v2 and v2-pro boards, but not the v2-mini.
It’s kept out as a cost saving measure mostly, so the boards can be competitively priced ( it’s the same for other components like the Vreg, and it used to be like that for the Ethernet connector ).
So I’m in the same boat… Well sort of I have 2.6 and 2.4 stuck on. Same as above been rocking for almost a year now without an issue. 2.4 was digital for hotend fan and 2.6 PWM for bed fan. Couple months ago 2.6 stuck on. Bummer but had a open mosfet so I just moved to the working one. Today I have just installed a L cheapo 3.5w laser and using 2.4 set to PWM to control it. All was going going good till 2.4 stuck and engraved a nice line across my cell phone case. So now with two mosfets down it’s time to figure out whats up. Powered down and tested across S-D at each mosfet and shorted with less than 1 ohm.
Is ZXMN4A06GTA the correct number for some new ones?
Also is there something with my setup that could be causing this? 2.6 was dual 12v .08 amp fan in parallel and 2.4 was one 12v .08 amp fan then the laser. The laser only seems to pull about 2 amps. Should I have been running a diode?
Yes, for fans and for any kind of inductive load ( don’t know enough about your laser driver to know if it could have kickback too ), you need a diode, or your mosfets will keep dying.
I just found that info in the guide. I skipped over it the first time around because I was only using one little fan originally. After upgrading the two in parallel would be pulling a bit much and I’m gonna guess the laser has some amount of feed back. It’s pulling around 2 amps so I could see how it took the mosfet out in only a couple hours.