The flatbed scanner module of this Canon Pixma MX340 multi-function inkjet turned out to be mostly empty space, which should hopefully ease a more detailed investigation later. Removing the scanner also unblocked the fasteners I saw earlier, allowing me to finally disassemble the base of this machine for a look inside.

I opened the base enclosure starting from its front right corner, where I found a very sturdily installed USB port. I remember this machine had the ability to scan straight to a PDF on a USB flash drive in this port, which was quite the lifesaver in the few times I needed that capability and needed it now. Behind the USB port is a thin sheet of clear plastic attached with double-sided adhesive. It looks like a shield... but against what?

I could see the USB port and shield is in front of where the print head carriage assembly is parked when it is not printing. I guess this shield is protecting the USB port from any errant ink drops that may spray from behind. I can see how we wouldn't want ink to drip out of the USB port onto our flash drives, but I didn't even know splashing ink was a risk.

Then I took a closer look at the print head parking area and saw ink-stained components underneath it. Oh yeah, I now see there's plenty of ink splash risk.

I pushed the print head carriage out of the way for a closer look at what lies beneath. There's a lot of ink stain from years of service. It's pretty clear the black cartridge lives on the right and the color cartridge on the left. For the color cartridge, it looks like the blue ink comes out of the left side and the yellow ink comes out the right. Curiously, I don't see much in the way of red ink (or more likely magenta) even though I would have thought red would leave the brightest stains.

The front-most white gear, heavily stained blue, is attached to one of two paper feed roller shafts. I can see it meshes with gears further back, but I couldn't see exactly what's going on down there without further disassembly. The most intriguing feature that caught my attention are what looks like tubes. What flows through those tubes, where do they come from, and where do they go?

In the foreground of this picture, we see an assembly that sits below the print head when it is parked. The assembly can move at least vertically, possibly horizontally as well. The topmost features are two rubber squeegees, one heavily stained blue and another stained black but not as heavily. Next to those squeegees are what I assume to be ink absorbent pads. All appear to be useful tools to maintain, clean, and unclog ink nozzles.

For comparison, here's a picture I took of the counterpart in a brand new Canon Pixma MG3620 before printing anything. I see many similar looking components, with the obvious difference of being factory fresh with clear squeegees and unstained white plastic.

Back to the MX340, I examined the print head carriage data cable and found it's actually three flex cables stacked together. I had thought such stacking invited electrical interference between cables, but apparently not a problem here.

Tracing the cable back towards the main control board, there seems to be a pit stop at a small circuit board.

It turns out to be only a mechanical clip to keep the cable in place, there is no electrical connection to the little circuit board. The little circuit board has its own four conductor cable, visibly gray in this picture. The board houses another photo interrupter sensor for something in the gear box beneath it. I can't see the rest of the gearbox, though, without further disassembly that carries a risk of breaking something. Since I want to poke around the printer in a still-working state, I am going to postpone gearbox investigation until later. I have enough other interesting things to look at.

This teardown ran far longer than I originally thought it would. Click here for the starting point.