Playing around with the print head maintenance mechanism on my old retired Canon Pixma MX340 multi-function inkjet, I got some ink on my fingers. I see this as a preview of what I expect upon further disassembly, and decided to procrastinate that dirty job. Instead, I turned my attention to a less messy part of the mechanism: the print carriage bracket for holding the two color ink cartridges.

It started out simple and straightforward: there were two small Philips-head screws in the bottom corners of the carriage. Remove them, and the outer mounting rail comes off easily. And since it could no longer hold ink cartridges or their integrated print heads, this is the moment when my MX340 stopped being a printer and became just an assembly of interesting mechanisms.

Once that rail was removed, the two spring-loaded lids followed.

These lids turned out to be more complex than I had expected. I knew there was a flexture mechanism in front to latch a cartridge in place, and I expected one spring because the lid pops up when unlatched.

There were actually three springs. The strongest one pushes a piece of white plastic that, when closed, pushes the ink cartridge to keep it in place. I thought that was a generic enough action that a common part could be used across both lids, but they each had their own uniquely shaped part for the job and I couldn't figure out why that was necessary. The third spring and smallest spring puts a tiny bit of tension on a small fragile (I broke it) black part whose purpose was not obvious to me. My best guess is it helps maintain proper spacing between the cartridge and its corresponding electrical contacts.

I had hoped removing rail and lids would have uncovered additional fasteners for further disassembly, but no luck. I've got a flat wall of ink cartridge electrical contacts and not much else. I had hoped to disassemble this carriage far enough to gain access to the linear encoder sensor, but no luck.

Looking around the side, I saw signs of additional fasteners, but they're facing the opposite direction. I think I have to disassemble the print cartridge linear rail assembly, possibly removing the linear encoder strip and drive belt, before I could remove the carriage and access these fasteners. I will have to revisit this later and, in the hopes of preserving the "probe it while it is running" option for later, I'll remove the whole horizontal actuator assembly as one intact unit.

This teardown ran far longer than I originally thought it would. Click here to rewind back to where this adventure started.