Resurrecting an inkjet printer, and dissecting a deceased cartridge

I purchased my Epson Artisan 730 color inkjet all-in-one (printer, copier, and scanner):

in September 2012, coincident with a move to Colorado (my even older Artisan 800 is still in occasional use by my wife). Speaking of “occasional use”, I’ve also used mine only sporadically, given that the monochrome outputs of the Brother laser multifunction printers in both of our offices work fine for most purposes and are significantly less expensive to operate on a per-page basis. Truth be told, mine probably still had its original ink cartridges installed when I recently tried to use it to print out a “batteries inside” notice, which needed to be bright red in color, to be taped to the outside of a package I was preparing to ship. And unsurprisingly, therefore, the result wasn’t as desired; the printer spat out a completely blank sheet of paper.

The inkjet cartridges, it turns out, were dried up inside (and/or empty; the software driver’s built-in diagnostics routine can’t differentiate between the two possible states). But when I replaced the cartridges with fresh ones:

the printer still spat out blank sheets of paper. That’s because, I eventually realized, the flexible multi-tube-harness that transports the ink from the cartridges to the print heads was also clogged by desiccated ink remnants (full disclosure: the following photo was snapped after the completion of the procedure described in the next couple of paragraphs):

Replacement harnesses weren’t available, my research indicated, and it also suggested that attempts to disassemble the printer were highly likely to lead to its demise. Determined to do everything possible to prevent this otherwise perfectly good device from ending up at the landfill, I kept plugging away with Google searches and eventually came across this video:

I went with this cleaning solution, and it took several fluid applications, each time followed by a few hours’ wait and then head clean and nozzle check operation attempts, but the Artisan 730 is thankfully back in business. I was left with the aforementioned “dead” inkjet cartridges:

which piqued my curiosity; how did they work, actually? And how did Epson and its competitors, such as long-disdained HP, both determine a particular cartridge’s remaining-ink level and attempt to prevent printer owners from using less expensive third-party alternatives? I decided to take one apart, randomly grabbing the light magenta one as my chosen victim:

Conceptually, here’s a how-it-works video I found that Wired Magazine did about a decade ago:

It’s not directly relevant here because, as I earlier noted, the print heads aren’t built into the cartridges; instead, they’re on the other end of the now-unclogged flexible tubing. But I still found the video interesting. And here’s a how-they-work (both in an absolute sense and vs thermal alternatives) Epson tech brief that I came across, which may also be of interest to you.

Also, in the earlier rubber-banded-stack photos, you might have noticed that the black ink cartridge has a “98” moniker while the others are “99”. Epson sells two versions of each cartridge color variant; “98s” have higher ink capacity than the less expensive “99” ones. A typical six-color bundle sold at retail combines a high-capacity black “98” (since monochrome printing is more common than full color, per my earlier mentioned Brother laser case study example) with standard capacity “99” variants of the others (more expensive all-“98” bundles are also available, obviously, as my earlier photos of the replacement cartridges indicate).

With that background info out of the way, let’s dive in. The cartridge enclosure construction is pretty beefy, understandably so due to the obvious desire to prevent leaks, and is further bolstered by a nearly impenetrable (for reasons that will soon be visibly obvious) sticker on one side:

That said, the seam around the install-orientation hole, whose purpose will be obvious once you see what the bay looks like absent cartridges (note the mounting pins toward the bottom):

and is on the opposite end from the same-side ink nozzle, looks promising:

And we’re inside. Behind that tough black plastic cover is, I suspect, the ink reservoir:

But for now, this electrical engineer’s top priority is checking out that multi-contact mini-PCB:

This side we’ve already seen in its installed state:

but the underside is now first-time exposed to view, too:

I’m guessing that under that opaque epoxy blob is the authentication chip (more likely, die). But if you look closely at the earlier mini-PCB-less shot, you’ll note that there’s still more “guts” to go below. Let’s get the broader plastic end assembly off next:

Whatever this is, I assume it modulates (and measures?) the amount of ink in the “tank” and flowing through the nozzle. Specific ideas, readers? A piezo something-or-other, mebbe?

And here are some views of what’s driving it (along with the earlier-seen mini-PCB, of course):

With no further meaningful progress seemingly possible here, I returned my disassembly attention to the sticker side, aided by a box cutter and focusing on the circular-pattern section you might have noticed in previous photos:

Hmmm. It appears that I’ve found the “port” used to fill the cartridge with ink on the assembly line. And it also appears that the cartridge still has at least some viable ink inside:

The light magenta dribble eventually petered out:

And after tediously piece-by-piece ripping off the recalcitrant black plastic sheet you saw earlier covering the other side, here’s what I found inside:

The ink-input port is the circular section in the upper left. Why there are so many chambers inside… Read Original