Canon print heads - troubleshooting tips
Helpful hints with regard to Canon print heads:
Canon print heads use a heat process to eject ink from the print head. Imagine a line of very small tubes filled with ink and little heaters near the tip of each tube. When the tiny heater momentarily heats up, a small air bubble forms in the tube. This, in turn, forces (displaces) a small drop of ink out of the tip. This is where the term “bubble jet” originates.
Legitimate print head failures are often really heater failures. Much like the filament in a light bulb, they simply burn out. Since this is part of a circuit that can be tested, most printers will then flash lights or display an error on your computer related to the print head. Sometimes the error may be a bit misleading; such a referring to head temperature, an incorrectly installed cartridge, a “wrong cartridge”, or missing cartridge. If the error is pointing even vaguely to the print head, that’s the best place to start looking for a solution assuming you’re not simply out of ink or using questionable ink cartridges.
Sometimes a print head error can be intermittent. You may turn on the printer and get an error one day then find it prints fine the next day. Going back to the light bulb analogy, testing print head circuits differ slightly from what you might expect. It’s not quite as simple as turning on or not turning on because the test is actually measuring resistance through the heater elements. More specifically, the test is looking for the resistance to fall within a certain range. Since resistance changes with temperature, you might have a print head that narrowly passes the test one day then falls out of range and fails at another time. Bottom line: If the heater is burned out it will certainly fail. If it’s still functional but marginal, the test results may vary.
Naturally most print quality shortcomings are related to the print head. Many, however, are not entirely the fault of the print head. At Compass Micro we often refer to third party ink as “bad cholesterol” for printers. If you use cheaper inks for an extended period, the nozzles in the head will begin to clog or build up residue that deflects the spray. Both issues result in “banding”. Banding generally shows up as faint lines through the image; either blank lines or discolored lines. As residue continues to build up an entire color may drop out causing discoloration of the entire image. This may be due to clogging nozzles but it may also indicate that the pump charged with cleaning the print head is clogged and no longer doing its job.
When you have a print quality issue the first step in troubleshooting the issue is to do what’s called a “nozzle check” test. In the Windows/PC world you can do this by clicking on Start, then Control Panel, then Printers. This should bring up a window that shows the printers installed on your computer. Right click on the name of the printer in question then select Properties. This opens the printer driver – the software that was installed from the CD that came with the printer. The nozzle check test should be under a tab named something like “maintenance” or “utility”. The nozzle check test prints a sample of each ink color in a grid or block pattern. Problems with print quality are usually obvious on the nozzle check sample.
If you’ve been using third party ink and a color has gone missing, try a new Canon brand ink cartridge before spending money on a print head. After installing the new cartridge, run a cleaning cycle and reprint the nozzle check pattern. Sometimes the color will come back with a fresh cartridge. If not, you’ll want the new ink for a new print head anyway. (We suggest putting new Canon brand ink in a new head rather than starting with cartridges that may be suspect.)
If you print a nozzle check pattern and ink is missing in a very regular pattern such as half a block is missing or every other column in a grid is missing you may be in a bad situation. Missing part of a color in a very regular pattern indicates that a portion of the head has electronically failed. Or that part of the signal to fire nozzles is not reaching the head. Unfortunately, there’s no way to be certain what exactly has failed in this situation. When we come across an issue like this we start looking for signs that something has shorted out. Remove the head and look for any obvious blemishes (or ink) where the electric contacts on the head match up to the contacts in the carriage unit. Inspect the cables as well. We sometimes find ink has found its way to where the flat ribbon cable plugs into the carriage unit and damaged the connections. Since ink is conductive this often means something has shorted out within the print head, main board, or both.
At this point, replacing a print head is risky. We find it sometimes fixes the problem but just as often points to a problem elsewhere. If the latter is true, you’ve likely written off the print head that was just installed.