Ender 3 Dimmer Switch Mod

thingiverse

LCD covers are cool, but they're not light-tight. Instead, modify the PCB to take full control of the backlight! This mod works in full daylight just as well as in total darkness, and requires no mounting hardware. Tested on Ender 3 Pro. ### You will need: * 1x potentiometer with switch. I used and recommend the [P170SP1-FC15AR10K](https://www.digikey.com/en/products/detail/tt-electronics-bi/P170SP1-FC15AR10K/5957483) - You can use a potentiometer without a built-in switch, but you won't be able to turn the backlight fully off if you do. It will just get very dim. If the potentiometer is a lower resistance value (e.g. 1k instead of 10k), the backlight won't get as dim before it turns off, but it will still dim somewhat. * 1x 100+ Ω resistor - The resistor determines the max brightness—more resistance -> dimmer max brightness level. So, feel free to use a higher-value resistor if you want to tone down the screen permanently, but be careful using anything less, since you could burn out the backlight with too much current. I think the stock resistor is slightly less than 100 Ω, but I can't remember exactly (I didn't have an exact match in my electronics closet, so bumped it up to 100). * Knob (to fit your chosen potentiometer, I recommend [this thing](https://www.thingiverse.com/thing:54024)) * Wire * Tape * Basic soldering ability ### Instructions 1. Turn off and unplug your printer. 2. Print the trimpot holder model and snap it into place. 3. Take off the LCD panel assembly. Remove the 2x M5 screws in the front, then carefully turn the sheet-metal part over and unplug the ribbon cable from the EXP3 port. 4. Use a soldering iron to remove R14. - Make sure your PCB has the same layout as mine! I don't think this board has any big revisions, but make sure, just in case. If yours is different, you'll have to hunt down the backlight resistor yourself. - Heat up one joint and use tweezers to slightly lift at that end, then switch to the other side and repeat. Go back and forth until it's free; don't pry too hard or you'll tear the traces off the PCB. - Or use an SMD rework station (hot air gun) if you have one. 5. Assemble the trimpot. Insert it into the printed holder, and fix it with the nut. I would hold off on the knob until the end. 6. Solder the potentiometer. You want the switch, the resistor, and half of the potentiometer (end to wiper, i.e. rheostat) all in series from one wire to the other. Then solder the wires to the spot where R14 used to be. - It doesn't matter which wire goes to which pad on the PCB. It also doesn't matter what order you put the series components in. - It **does** matter which side of the potentiometer you use—one side will put max brightness on the left (where it clicks off), and using the other side will put max brightness on the right. This is a matter of taste, but I put bright on the right, so that you can turn it off without a bright flash. - You'll have one unused pin. I folded mine in to keep it out of the way. - See the photos for how I wired mine. 7. Tape down the wires so they don't catch on anything. Also leave some slack so you can remove the trimpot holder without pulling the wires off. 8. Reattach the LCD assembly to the printer. You're done!