Instructions for Refilling HP 2000/2500/CAD Printers

Please note: This is not an HP approved procedure. Do not put anything other than our recommended ink into the cartridges. We will refund what you paid for the refill kit and ink if you are not totally satisfied. This procedure is new and is subject to change without notice. It is intended for use by the printer owner.

C4841A, C4842A, C4843A, C4844A REFILL INSTRUCTIONS

Step One:
Cut the label that holds the End Cap in place, see photo.
Use a razor blade to cut label. Be careful not to go too deep. Go deep enough just to cut label. Cut the label on both sides of the cartridge.

Step Two:
Remove the End Cap, see photo.
Gently pull on the cap and it will separate from the plastic housing.

Step Three:
Make extraction tool, see photo.
A pair of needle nose pliers or flat nosed pliers will do this job nicely. Bend about 3/32 of an inch 90 degrees. If the bent part is too short or too long, it won't work as well.

Step Four:
Remove rubber plug from fill spout, see photo.
Start pin into plug with pin horizontal. As you get the tip started into the plug, straighten the pin so it is vertical. Make sure the tip of the pin is firmly inserted into the plug. Then, gently pull on the pin and the plug will come out. Try not to damage the plug too much, it has to go back in place and still seal.
The hole you are opening by removing this plug is where the ink goes in. Don't do anything with the stack (tube sticking up with a metal cap on it) on the opposite end. This is the printer interface valve. Leave it alone.

Step Five:
Fill the foil bag with ink.
If you have a squeeze bottle of ink, attach the needle cap to the bottle. Make sure the o'ring is installed in the cap. Tighten the cap on the bottle and attach the needle to the cap. If you have a syringe, attach the needle and load 12 cc of ink into the syringe.
Before injecting the ink, make sure the foil bag inside the cartridge is not collapsed. You can blow into it using a large diameter straw or a piece of 3/8" ID tubing. If the bag is collapsed, you won't be able to put the full amount of ink in it.
Slowly inject the ink into the cartridge through the hole opened when the rubber plug was removed in Step Four. Insert the needle just far enough to get the ink in the foil bag. If you go too far with the needle may damage the foil bag. The cartridge, if it was empty, will take one ounce of ink, or about 30 cc total. Don't over fill or it will make a mess. Also, don't shoot the ink in fast, it will make foam. Foam is undesirable.
You do not have to remove the foil bag from the plastic housing to do the filling. But if you do, be sure to put it back in correctly. The stack or printer interface valve goes opposite the arrow on the top of the cartridge.

Step Six:
Clean the rubber plug and install it back into the hole it came out of. It doesn't take a lot of force, so be careful not to push it all the way into the foil bag. It will sort of snap or pop in place. Use a retracted ball point pen or similar device. It has to seal air tight, so make sure it is in place properly.
Note: One of our customers says that he uses the dumb end of a 1/8 drill bit and has installed a screw on drill stop on it so that only 4.5 mm (.177 inches) is used to push the rubber plug back in place.
Next, reattach the End Cap and secure it in place with some scotch tape. Put the tape only where the label was cut in Step One.
Done !! Reinstall the cartridge and run a couple of cleaning cycles.
HP has a lot of technology in this cartridge, including a smart chip that knows it has run out of ink. This smart chip disables the bar charts and level indicating software. It does not prevent the operation of the refilled cartridge. When your refilled cartridge becomes empty again, the printer will recognize it and send you an "out of ink" message. Someday, HP will use their chip to prevent refilling, but they have not done it yet.
It is not illegal or unethical to refill your own cartridges, as long as you own the printer. If you do it commercially for others, you will be on Hp's unfriendly list.

Theory of Operation

Ink from the foil bag (reservoir) passes through the check valve and fills the diaphragm. The plunger and spring keep a constant force on the diaphragm, forcing ink out to the print head. When the diaphragm is depleted of ink, the limit switch is triggered causing the actuator to pull the plunger back away from the diaphragm. The diaphragm regains its original shape and in the process pulls more ink across the check valve, restoring the original condition. The actuator is then activated, applying fluid pressure to the print head.
This system is unique in that it keeps constant ink pressure applied to the print head and it senses when the cartridge is empty. If the diaphragm does not fill with ink, when the plunger returns the limit switch is activated a second time in a short period of time, signaling that the cartridge is empty.

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