Introduction: Samsung CLP-365w Laser Printer DIY Imaging Drum Unit Reset
This article describes how to get your Samsung printer working again without shelling out a fortune for a new Imaging unit. If you just want to know how to do do it, skip to the next step, the rest of this step is just an explanation of how I figured this out! Note that this worked for my CLP-365w printer but it may work for other similar Samsung models too. It will certainly work for any printer that uses the CLT-R406 imaging unit but I suspect they all use a similar technique to reset the page count.
The story:
Samsung produce a very nice range of domestic laser printers for the home, they're quite cheap too. However, they have engineered in some cunning ways to make money. All of the consumables for these printers (toners and the image drum) need to be replaced when the unit tells you, otherwise the printer will not print. So even if you manually fill up the toner cartridge, the printer still "thinks" it is empty and will refuse to print. I am not going to cover manual toner refilling here but there are plenty of guides around.
The other "consumable" on these printers is the so called "Imaging unit". It's a drum which is an essential component in any laser printer and it is used to transfer ink to the page in the printing process. To be fair, this component is a consumable, it will wear out eventually causing blurry or streaky pages etc. These Samsung printers have a kind of printing "odometer" that records how many pages have been printed using the current imaging unit. They also have a built in hard coded lifespan of about 5000 pages (i think...). So once we hit this page count, the red light of death illuminates on your printer and we get a lovely message saying "Warning, prepare new imaging unit". At first I thought, "ahhh its ok, it's just a warning, I'll carry on printing until it really needs replacing" - wrong. The printer literally won't print anything until you replace the imaging unit. So, I look online - wow £75! What a rip off! The ink cartridges for these things cost a bomb (so far I have just paid up but I will probably start refilling soon) but this is beginning to take the p*ss I thought!
I decided to take the Imaging unit out and examine it - surprise surprise, it looked perfect, not a single blemish or mark, hardly any dirt (not sure what a knackered one looks like to be fair, but this looked brand new to me). Also, the pages printed prior to this were perfect as well, there as never any sign of degradation.
A quick google search reveals many places offering to sell you a "reset chip" for around £15 with instructions, it's like magic, you just unfold it, plug it onto the imaging unit, close the lid and taadaa! The printer "thinks" you've bought a shiney new imaging unit an happily prints away.
I was about to punch in my card number and be done with it but then I watched the instruction video and took a closer look, I could see that this "reset chip" was really just a 30p resistor stuck to a piece of plastic. Cunningly, all of the photo's and videos of these chips seem to show it covered in a black lacquer so you can't see the coloured ribbons on them. Of course they've covered this up, they wouldn't want their little secret getting out! Well sorry guys, I know your game! These people are almost as bad as Samsung, packaging a 30p resistor up and selling it for £15!
After a bit of research, I discover how these things work. The imaging unit has a small removable plastic housing with 2 resistors in, one 200k ohm, and one much weaker 56ohm fusible type resister, in parallel. When it first powers up, the printer detects a low resistance. The printer passes a current though the drum unit and the small "fuse" resistor blows. From now on, when the printer powers on, it only detects the 200k resister so it knows this is not a new drum so the printer counts all the printed pages from now on. 2 years down the line, we hit the magic number and the printer stops working because it "thinks" the drum is now useless. So you go out and buy a new drum, it has the same 2 resistors inside, only the smaller one is not blown. You plug it in, the printer sees a low resistance again, it knows there is a new drum, so it resets the page count and then blows the new fuse and the cycle repeats. Now, if instead of buying a new drum unit we just replace the fuse, we can "trick" the printer into thinking we have a new drum unit. Simple. This is exactly what the £15 kits are doing, they are simply a new 56ohm fused resistor which you stick across the terminals.
Step 1: Crack Open the Front of Your Printer!
Open up your printer and locate the imaging unit. On my printer, it was at the bottom, below all of the toner cartridges.
Notice on the front of the Imaging unit a small black plastic housing with 2 copper terminals on it. It looks removable, and indeed it is!
Step 2: Remove the Imaging Unit Fuse Housing
Once you have located the fuse housing, pry it out.
I used a small flat headed screw driver. Careful not to break anything now.
Step 3: Examine the Fuse Housing
Take a look inside the fuse housing. It will either have one or two resistor components.
Older articles and guides show it having two, but mine only had one. I guess it doesn't need a fuse when it is first manufactured because the page count is already 0. At some point Samsung stopped factory fitting the second resistor.
Either way, it will definitely have a 200k Ohm resistor and optionally a blown fusible 56 ohm resistor. If you wish, you can remove the blown fuse resistor (if you can identify it). It doesn't matter if you leave it in place though.
Step 4: Find a Replacement 56 Ohm Resistor
Source a replacement 56 ohm resistor. I sourced a standard resistor rather than a fusible type. (This way I can reuse it many times to reset the page count.)
You should be able to get the resistor from an RS or Maplin (Radio Shack in the US maybe?) for about 30 pence or you could order one online. Heck you could probably salvage one from a broken electrical device - in fact some have reported this DIY fix working with 47ohm resistors - so if you do try to salvage one, it might just be that you need a very weak resistor, not specifically a 56 ohm.
Step 5: Piggy Back the 56ohm Resistor Onto the 200k Ohm Resistor
We need to get that new resistor in there with the 200k ohm briefly and power the printer on. I suppose you could solder it in permanently, this will basically reset the page count every time the printer turns on. But this is designed to be a fusible resistor that blows, so I don't know if there is any concerns about this component overheating if you do that. In my case, I just rammed it in the housing roughly and twisted the component legs around the existing one to form a connection. In the picture, the blue resistor is the 56 ohm one.
Now plug the fuse housing back in and power on the printer. Taadaa! It takes a while but it will reset and the red light will go out. Congratulations, you just bought new Imaging unit for 30 pence.
If this didn't work for you then try the following:
- Double check that your new resistor is making proper contact with the existing one
- Make sure the component legs aren't doubling back and making a short circuit.
- Make sure the resistor is the correct value. If you have a different model Samsung printer you could try different resistors. I don't think you can do much damage here, you're simply adding small amounts of extra resistance.
I then powered the printer off and removed my 56 ohm resister just in case there are any issues with leaving it in. I'll keep that bad boy, i'll probably need it again in 2 years ;)
Note that your imaging unit will genuinely need replacing one day (supposedly). But if like me your unit is still functional, then go ahead and apply this little trick.
