The new line of Canon printer's now has a chip on the cartridge. By turning off the ink monitor, they can be refilled.
Canon does show in their operation manual how to turn of the ink monitor. Canon's new smart led lamp flashes when ink is running low, and flashes even faster when near empty. When you install a new ink tank, the smart led system will glow to let you know that the cartridge is installed correctly. I feel that they use this smart led to stop people from refilling their cartridges or a lease make it harder.
I did some testing on Canon's new ip 4200 printer, this model has the lock out chip on the cartridges.( I call it a lock out chip). I loaded the printer with some plain paper and I printed an 8 x 10 square of solid yellow. After about 90 or so sheets the printer showed a low out of ink warning. I kept printing, and after another 40 or more pages the printer stop printing. The out of ink symbol came on and I could not print any more. Cartridge page yields are based on a 5 % original.
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I followed the procedure in the operation manual on how to turn off the ink monitor. So far, I have refilled the same cartridge four times and have had no problem