This mainboard cover was designed in preparation for K8400 upgrade with silent drivers TMC2100. These drivers require good ventilation, that's why 80mm fan was placed inside the cover and is directly facing the mainboard. The cover can also be used with original VM8400DB drivers with DRV8825 chip as shown on attached images.
I used Evercool 80mm x 15mm DC 12V Ball Bearing Brushless, Low Noise Fan EC8015M12CA. You can replace it with any other 12V DC 80mm fan, but make sure its height does not exceed 15mm. This fan replaces the bottom fan that connects to FAN2 connector of the mainboard. The air should flow towards the mainboard.
The cover contains 5 separate printed parts and 2 metal mesh inserts. I cut out mesh from office set similar to one shown on the last image, but any 1mm thick metal mesh can be used.
Assembly
- Disconnect printer from AC power (unplug the power cord).
- Make sure 80mm fan has correct connector type.
- Attach the fan to the top thing with four M5 x 12mm screws. Having fan guard is optional, but highly recommended.
- Optionally install toggle switch into the hole in long_side2. It should connect to programming pins of the mainboard (JPROG). You will use it when flashing the firmware.
- With eight M3 x 6mm screws attach short sides to the long sides. Slide in mesh inserts before tightening the screws. Mesh insert dimensions are 86mm x 32mm x 1mm.
- Mount the mainboard and 4 sides of the cover to the bottom panel of the printer. Use four M3 x 16mm screws. The screw should go through the bottom panel, then spacer, then mainboard and end in the long_side hole. When mounting the mainboard make sure its power wires stay outside the cover.
- Plug in toggle switch connector to the mainboard (JPROG).
- Check all wire looms; make sure excess wires are outside the cover and not blocking airflow through meshes.
- Plug in 80mm fan connector to the mainboard (FAN2) and attach the top with six M3 x 8mm screws.
I am not using reset button that came with K8400 because the printer has another one doing exactly the same. It is located above SD card slot.
As you can see from the images I relocated the power supply (as part of another upgrade), but the cover should fit just fine when the power supply is at its original position.
Bo_Ris
