by Sigmoid » 2014-Dec-Sun-13-Dec
Lol this is so bad! The Rev G board should feature a polyfuse on the fan wire. :/
edit: lol I found out that there IS a fuse, haha. Though apparently the MOSFET blows faster than the fuse. At least the board didn't burn. I wonder if the circuit could be easily improved to soak the excess current while the polyswitch blows, protecting the FET.
Anyway, one more FET blown. I'm browsing Mouser for a better specced alternative.
I managed to kill mine by trying the measure the voltage with a multimeter, and accidentally shorting it out. The reason for trying to measure the voltage was that after connecting a larger fan, I noticed that when the heated bed is turned on, the fan rpm drops... Now that obviously means something is underspecced for either the bed, or the fan.
When voltage starts sagging, I always start being afraid whether something on the board has found a new purpose in life as a space heater. So I wanted to compare the voltage curve on the fan pins, and on the ATX supply itself - if it's the ATX that sags, I think I can live with it, those are robust as hell.
BTW, those with shipping issues, stop trying to source the FET from the US. Find a local, Australian dealer, and get it from there. I was under the impression Digikey has a local facility in Australia, but if it doesn't, there should be some alternative. You can print out the datasheet of the FET, and take it to a brick and mortar electronics shop in your town, and ask them to give you an alternative with the same form factor and similar specs.
Last edited by
Sigmoid on 2014-Dec-Sun-15-Dec, edited 5 times in total.