Control Board MOSFETs

A project log for Monoprice Select Mini Electro-Mechanical Upgrades

Endeavoring to build upon the existing fanbase work of this $200-ish printer.

Michael O'BrienMichael O'Brien 08/16/2016 at 22:170 Comments

I've had a chance to go over datasheets with Engauge Digitizer for over a dozen MOSFETs. Here is a quick top 5 list of best picks if you wish to switch yours out. Keep in mind, @ 147.5 Hz, switching losses aren't that high so Rds(os) dominates. This means that the stock MOSFETs dissipate ~0.75 W on full duty cycle.

Stock - AOD484

Top Choice - AOD240 (~45 mW dissipation)

2nd Place - IPD031N06L3 (~57 mW dissipation)

3rd Place - AOD510 (~67 mW dissipation)

4th Place - IPD031N03L (~70 mW dissipation)

5th Place - IPD036N04L (~86 mW dissipation)

One of the photos for the project is of the 1N4448TAP diodes I'm using to protect the MOSFETs, stock or otherwise. Here is a capture I forgot I had of the stock 'FETs and the voltage spike that occurs during the operation for both the hoetend and heated bed. As soon as both of these turn on, you will have a spike for both line up with each other from time to time. Even without that, this spike equates to about a 9.7 a draw over a duration of ~180 ns. I bet this is why the stock PSU likes to fail...