Why HP 3500 / HP 4600 could leak and what to do Ink and Toner Refill Help Instructions Forum

InkGuy · Professional Support Joined: 26 Jul 2005 Posts: 129

The leaking thing is very uncommon UNLESS the filling hole is not sealed properly. Make sure you get a tight seal with duct tape. In some cases that you don't have a perfect seal, it is advisable to smoothen the area around the hole with a sharp instrument, like a sharp knife or even sand paper. Please make sure that shavings do not fall into the toner compartment and also working with a sharp instrument could lead to injury if one is not carefull. Other than that I could not see a reason for the cartridge to leak from another area. Also please note that these cartridges can be refilled 1-2 times only as they have a waste compartment that once it gets full needs to be emptied, but that is a specialised practice.

LEAKING CARTRIDGES (LJ4600/LJ3500)

You may get asked why toner leaks from toner cartridges, specifically the LJ4600/4650 and LJ3500/3700 type printers.

We all know HP designs their cartridges to make one good cycle, the designated yield of the cartridge at 5% approx. page coverage. Equally the components within the cartridges are also only designed to make a limited amount of print images. Unfortunately with the newer designed color cartridges we are finding the re-manufacturer has to deal with a new problem of leaking toner.

Why do they leak? The plain answer is WEAR!

If you look at the Developer roller and doctor blade together, their relationship is paramount to cartridge performance. They live together throughout the entire OEM first cycle, any defect between these two items quickly results in cartridge failure.

To work out why these components wear is not difficult, one of the main factors is the amount of revolutions the Developer roller makes against the doctor blade, when you add this up it becomes apparent the difficulties we face when trying to remanufacture the cartridge, for instance:

To keep this simple, and not exacts, for each print image from an LJ4600 printer the Developer roller turns approx. 7 times across an A4 piece of paper. The expected yield of this cartridge is 8000 pages at 5% coverage, which equates to 56,000 revolutions of the developer roller against doctor blade. Of course each time you turn the printer on, and every time the printer automatically calibrates, again the Developer roller revolves against the Doctor Blade, I do not know the amount of times it does this, but at a guess I would say a minimum of 5000 revolutions throughout the life of the cartridge, so we can say our virgin OEM cartridge ready to be remanufactured has already made 60,000 revolutions between the Developer roller and doctor blade! If the cartridge achieves a life cycle at 5%. Clearly, we can understand why leaking becomes an issue.

Why do some cartridges leak and others do not?

Not every cartridge achieves its full life cycle at 5% coverage. Whilst we are told that if we used our color printers to print letters, with a color logo at the top and bottom, our cartridges should last the designated yield stated by the OEM, invariably when we get a color printer, we start using the colors for printing pictures, and colorful spreadsheets etc. thus using much more than a 5% coverage. Many of the newer color laser printers are aimed directly at the home user β€“ LJ2600 for instance, where 5% coverage means very little and will probably never be achieved. So many of the cartridges have never made a full cycle at 5% coverage. These obviously are much better for remanufacturing. Other factors also come into the equation such as Chip management, paper media type etc. but keeping it simple.

Why do the Yellow or Black cartridges always leak first?

For the Black, of course we still print with more black toner, than any other toner in the set because it's always going to be the standard, in many cases the black cartridges in color laser printers have larger fill sizes to accommodate the extra workload required from them. So it should be no surprise to find that the Black cartridges receive greater wear rate and why we expect them to suffer from leaking issues.

The Yellow cartridges can have leaking issues because, out of all the colors it is used the most, you can find yellow toner mixed in with many colors, it's seen in reds, greens, shades of Cyan, Magenta and Blacks. So when you look at a print image and think the black looks bold and dark, look again and you will see yellow toner (others toners can be used also) contained within the black.

Also, and unknown to most people is Yellow toner gets used by the printer, for calibration and page marking. For instance if we print a completely clear blank page in the LaserJet 3500, with the naked eye we see a blank page, but if we use a 40x microscope we can see Yellow toner markings all across the page (pic1)

These Yellow toners particles are specifically put there by the printer, and itβ€™s on every page ever printed by the printer.

So, this is why the Yellow cartridges leak β€“ because although itβ€™s using less toner than the Black cartridge itβ€™s actually doing a lot more work in the printer.

Cartridge leaking can be stopped by replacing components; of course finding reliable cartridge components is not easy. From my experience I believe that these cartridges and toner performance can be achieved through good remanufacturing procedures

Also toner charge plays a role in reducing or stopping leaking, not covered in this email.

Hopefully this helps with why these newer HP cartridges are prone to leaking when being remanufactured.