Repairing and Modifying a Sharp CE-140P Printer/Plotter and EA-600 Ink Cartridge

Sharp CE-140P dot matrix printer and attached PC-1470U

A recent request for assistance from an online friend searching for help in getting his Sharp CE-140P printer running, prompted me to take a closer look at a project I've been ignoring for too long. 

The Sharp CE-140P inside its case

A view of the unit itself...

and from directly above...

To allow for adjusting the contrast when the unit is docked in the printer, the Sharp engineers had a brilliantly simple solution: A rubber wheel is pressed against the contrast adjustment wheel of the Pocket Computer. Also shown, the 15 pin connector.

The Sharp CE-140P is a strange one. While technically a color dot-matrix printer, it also combines the X-Y capabilities of a plotter, albeit with the most cryptic printing language I've seen. 

Yeah, that's the syntax I'd expect to draw a triangle

On a related note, all the English language versions of the operating manual you can find online are missing page 38 & 39.

The CE-140P is designed for the double height Pocket Computers with a 15 pin SIO connector such as the PC-1350 or PC-1475. As with most of Sharp's Pocket Computer printers, it includes a rechargeable battery pack. As per usual, they were leaking on my unit, so I removed them, cleaned the leakage, and stored the unit.

That was two years ago. Recently, that previously mentioned friend reached out for assistance in getting his CE-140P running, and that's when I took mine out of storage and got around to fixing it.

First on the agenda was deciding on whether to put in a new battery pack. 

In the past, this was always the first step, but I realized that I'm not actually using any of my units away from mains, and most of the time, the packs are flat when I want to use them.

A chap on Twitter had converted his CE-140P to a battery-less unit, and I decided I wanted to go that route as well. Internally, I desoldered the contacts from the DC jack. I soldered 150mm leads with a JST 2mm PH 2-pin connector to the DC jack and plugged that connector to the battery input on the printer board.

These 2 Pin JST PH 2mm connectors fit the battery connector on the board after shaving off the nubs on the side. These were a bit too short for my needs. I used 150mm lead length.

Above is a short video of me testing if the unit would work with 6V going from the DC jack directly to the battery input. 

While I was at it, I switched the polarity to center positive on the jack. I added a p-touch sticker to the case to remind me of that fact. I plugged in a universal adapter set to 6 V, and everything jumped to life once I switched the printer on. If I want, I can always make a battery pack that plugs into the DC-jack.

Now there was the problem of ink. The CE-140P uses EA-600 printer cartridges. These have four tiny chambers filled with ink.

The EA-600 printer cartridge. Probably been dry for the past 30 years.

My unit only had the single one installed, and NOS is rare as hens teeth. Since there is a dearth of pictures of the actual printer cartridge and print head on the Web, I've uploaded a few glamour shots below.

EA-600 cartridge in situ

Close-up of the print head

Print head and cartridge in normal operating position.

Twitter once again came to the rescue. A friend there had refilled his cartridges with cheap third party ink from a canon inkjet refill set. I ordered this set off Amazon: https://www.amazon.de/dp/B00821JB68 and a small hand drill with some micro bits: https://www.amazon.de/dp/B088PKZZ58 . I have insulin syringes I got cheap off eBay for some other project, so when everything arrived, I went about drilling a very tiny hole in each of the cartridge chambers and then filling each one with ~0.15 ml of ink and 0.30 ml for the black ink. After filling, I sealed each hole with kapton tape.

Time to get drilling

The first test print showed that black was apparently clogged, so I carefully(!) took the print head out of the unit and let it soak in a tray of IPA for a bit (Pic 16-17). The print head is permanently attached to a ribbon cable so take extreme care not to break or tear it! Make sure to remove the ink cartridge from the head before soaking in IPA.

After soaking, I dried the printer head off, reinserted it in the printer, popped in the ink cartridge and success! Everything works perfectly. 

Incidentally, the same place that offers those extremely expensive EA-850 plotter pens, also offers compatible 114 mm paper rolls for the CE-140P, though you'll need to do a bit of unrolling first as they're probably too thick to fit in the paper tray. ( https://www.evident-shop.de/.../papierrolle-114-mm-breit... )