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UPDATED: New and improved and addtional configurations
You may need to rotate the model to fit on your bed.
There are multiple models so that you can choose your configuration. The left configuration seems to be the most popular. If you want the MOSFET board on the left, pick the model marked left.
Probably everyone with a Monoprice Maker Select, Wanhao i3, or Cocoon Create who uses the heated bed should consider moving the high current and heat off of the main Melzi board to ensure long life of the main board.
The [Heat Bed Power Module Expansion (MOSFET) board](https://www.amazon.com/gp/product/B01HEQVQAK?tag=russianpaladin-20) achieves that and is easy to install:
There are various sellers of this board, available from multiple sources such as Amazon, eBay, and Ali Express.
Some people are printing standoffs and taping or hot gluing them in. I wanted something a bit easier and more secure. This standoff fits over two of the existing standoffs for the main board, and so it is firmly screwed in place.
**Parts needed (single MOSFET board)**:
- 4 x M3x5mm 0.5mm pitch screws (can use up to 6mm length)
- 4 x nylon washers
- 14awg or 12awg wire
The threads on the standoff are M3 0.5mm, the same as the original standoffs for the main board. Buy 4 M3X5mm (0.5mm pitch) screws and 4 nylon washers. You'll use the 4 screws and washers to mount the expansion board to the standoff.
**Purchase Links**:
[MOSFET board](https://www.amazon.com/gp/product/B01HEQVQAK?tag=russianpaladin-20)
[14awg Wire](https://www.amazon.com/gp/product/B01CMHQ8R2?tag=russianpaladin-20)
[Ring Terminals](https://www.amazon.com/dp/B000BVZBRU?tag=russianpaladin-20)
[Terminal Connectors (preferred)](https://www.amazon.com/gp/product/B07DQKSPWC/&tag=russianpaladin-20)
[Terminal Connectors (pluggable)](https://www.amazon.com/gp/product/B00BHU26AO/&tag=russianpaladin-20)
**Installation Instructions**:
- Remove the SD card from your printer's control box
- Disassemble the control box
- Remove the existing Melzi main board from the control box (keep the screws and washers)
- Screw the MOSFET expansion board to the printed standoff using the 4 new washers and screws
- Place the larger, unthreaded, holes of the printed standoff over the middle two standoffs built into the control box cover for the main board. (Note: You can install the standoff feet up or feet down.)
- Screw the main board back in over top, using the original 4 washers and screws
- Use the wiring diagram for your MOSFET board (provided by the seller) to finish the installation
**Be sure to remove the SD card before you remove the main board to ensure that you don't damage the SD slot when removing the board.**
Read more about the problem here:
[The Melzi Problem, or, Why Did My Wanhao i3 Duplicator Catch on Fire?](https://blog.adafruit.com/2017/03/23/the-melzi-problem-or-why-did-my-wanhao-i3-duplicator-catch-on-fire/)
**Control box disassembly video**:
https://www.youtube.com/watch?v=bXQ1gAid17Y
rawlogic
