Introduction: How to Fix Common Issues on Samsung CLX-3186 Series Laser Printer

Hello everyone, after a very very very long hiatus I'm finally back. This time with a proper Instructable!

I hope this can help you keep your printer running for a long time and reduce the e-waste problem.

This instruction will teach you how to fix these issues:

  • Yellow lines on top of print when printing color
  • Unfused toner at places
  • Printer pulling multiple pages or getting jammed
  • Toner nag message ("REPLACE TONER" message)

I'll add more pictures when I replace the fuser unit.


  • PH0 screwdriver
  • Jeweler's flathead screwdriver
  • Flathead screwdriver
  • A dark, dry place to keep the toners and other sensitive parts in
  • Cup or other containers to keep the screws in
  • Gloves
  • Air duster
  • Access to window or air purifier
  • Dust mask
  • Small plastic bag

Step 1: Open the RIGHT Side of the Printer

It is highly recommended to remove the waste toner cartridge (and empty/cap it), all toner cartridges, and the imaging drum and store them safely away from any abrasive materials or light (especially pets and kids) before doing this. Especially avoid sunlight as the imaging drum (the green cylinder) is VERY sensitive to sunlight and can get damaged by light.

First, start by unplugging the printer from the power and removing the single screw from the back of the printer, where the cables go. If you don't unplug the printer and you touch the power supply inside, you might receive a fatal electric shock. I recommend putting the printer on its side on a firm, steady surface.

Open both back paper jam door and front toner door.

Then, using a flathead screwdriver, release two clips from the bottom right side of the printer. There are two circular holes near the paper tray.

The left side contains a high-voltage power supply and should not be opened in this case. It goes up to 1000V. You don't want to touch that.

After you released the bottom clips, go around the side panel, and release each clip. It should not take much force, and you are supposed to pull on the thick plastic piece that goes next to the paper tray (not the outermost panel, this will break it)

Like you take the front panel of a computer case, give it a firm pull around the panel and it should release. Refer to the image for the sequence of operations.

Step 2: Unscrew the Main Logic Board

Now you'll see the mainboard. The connectors are all different, but you might want to take pictures of the board before you proceed further so you have something to refer to if you are confused.

Mark the connectors with colorful permanent markers so you can see exactly where everything goes.

When you're ready, carefully unplug each and every connector. Do not release the wires from the cable organizing clips since there are many connectors that can get very overwhelming to deal with.

Few connectors, especially the longer ones, may need a jeweler's screwdriver to release the clip.

Unscrew the 4 screws marked in the picture. Keep the screws in a safe place.

Note that the wireless version of the printer has two more connectors near the bottom right corner and one of them must be connected to the ground. There is a loop icon on the board itself where it goes, so keep that in mind.

Step 3: Remove the Main Gear

Near the top of the brown board, there is a plastic piece with one screw that covers front door switch. Unscrew it and set it aside.

Undo the seven screws marked in red and pull the main gear assembly out by pulling it towards you and wiggling a bit. You may want to check if you did unplug the motor wire before doing so because if that breaks, you'll have a bad time.

If your only problem is the printer pulling multiple pages, unscrew a single screw near the yellow cylindrical component near the bottom right corner and wiggle it out.

Remove the rubber pads on the metal pieces and replace them with a new EVA or rubber pad with 1mm (top metal piece) and 2mm (coil side) thickness. You can get them as "anti-skid pads" or "noise prevention pads" in the home improvement stores. Cut it into shape and stick it where the previous one was.

Wiggle it back into place, making sure not to pinch the thick wires, and tighten the screw.

You're done but test the printer first before putting it all back together.

Step 4: Cleaning the Solenoid (Yellow Line Problem)

Flip the main gear assembly. You'll see two cylindrical objects near the top and near the middle. Those are the solenoids, and if you have this problem of yellow line appearing, the rubber pads might be too degraded. The machine can function without those, so the easiest way to fix it is to simply remove the rubber pads.

Push down on the top metal plate (which moves) and if you hear a delayed click after you let go of it, the rubber pad is bad.

Grab a flathead jeweler's screwdriver and carefully insert it between the top metal plate. Scrape off all the remaining rubber pad. For the top solenoid, undo the screw, and remove the solenoid. Then do the same.

After you got rid of all the sticky residue and the top plate springs back into place after you press and release it without any delay, you're done. Re-attach and reassemble the solenoid to the main gear assembly.

Before proceeding further, dust the printer thoroughly with an air duster, especially the black film inside the unit and around where the gears sit.

And whatever you do, DO NOT TOUCH THAT FILM.

Step 5: Reassemble the Printer

Wiggle the main gear assembly back into place, making sure there are no cables that are pinched.

Look inside the printer and you will see various gears poking out of the hole on the right side of the toner storage area. If it's not, the assembly is not put in correctly.

If it's at an angle, it's not in all the way. Wiggle it more until it fits. When it does fit in, the screw holes will match up with no gap between the pillar and the screw hole.

Screw the main gear assembly back into place. To make sure you don't make a new thread, turn the screw counterclockwise until you feel a click, then turn it. There should be only a weak resistance. If not, back out and try again.

Reattach the cables to the mainboard by plugging them in. Thankfully, most plugs on the board only go into one spot, so it should be easy.

Screw the board back into place, making sure to not forget the grounding wire for the wireless models.

Click the side panel into place.

Step 6: Disabling the Toner Sensor

Warning: Running the printer in this state will void your warranty if it hasn't already expired. This disables toner CRUM detection (which is what the printer uses to tell whether or not the toner is full). If your printer already has a new toner, do not try this modification, although it is reversible if done my way.

Undo the 4 screws on the toner door. Push the spring-loaded holding peg thing away and lift the cover.

Undo the clips and screws on the circuit board. If the connector comes off, re-plug it.

A bunch of metal pegs will fall onto the circuit board. If not, push it from the cover.

Put them in a small plastic bag and stash it inside the empty space behind the cover. You will need those when you undo the modification.

Reassemble the front door and close the door. If the nag message goes away and the supply status printout reports 100% of toner remaining with the supplier code of INI, you're done.

If not, you can purchase third-party toner chips you can put on top of the stock toner chips to make it work again. Make sure you undo the modification first (the peg goes into the hole and the spring faces the circuit board) and turn the printer off before you put the "new" cartridge in.

Step 7: Blotchy or Unfused Spots on Document

This means the fuser roller is bad. Sometimes a piece of roller comes off alongside the finished document!

I was unable to determine how to get it out, but you'll need to take the top off (scanner, top cover), undo 4 screws inside the back paper door, unplug two cables marked inside the printer and remove it by lifting it upwards.

And that's it! Hope this helps, and see you next time!