The HP 2225 ThinkJet
For some reason, @DosFox decided he didn't want his HP ThinkJet printer and listed it on the hackspace's "hack bay" channel. I'm quite excited about old printers, and this one's so small it wouldn't take up too much space. I failed to resist temptation and ended up with a slightly broken printer. DosFox did warn me that at least one line wasn't printing due to cracked traces on the flex PCB running between the main board and the cartridge holder.
I dismantled the printer and attempted to fix the flex PCB by applying a small amount of solder paste and quickly touching it with the iron. This worked for one line, but not another, and I ended up melting through the flex PCB trying to repair it. Searching around the web, I was quite surprised to find that no one had designed a replacement. Or at least, if they had, they'd not posted the gerbers anywhere.
So, I'm here to fix that. You can find the KiCAD source, gerbers, order information and manual steps, in my git repository.
https://git.aaronsplace.co.uk/cgit/HP-2225-Flex-PCB.git/about/?h=main
The flex PCB works perfectly and it's now printing very reliably. I've also been trying to print graphics. Sadly there doesn't seem to be PCL (Level 1) support in CUPS. I suppose this isn't too surprising given ThinkJet was probably one of the only printers to use it. Despite this, I was able to knock up a little bit of Python to print small images. I'm not able to print images larger than 96 pixels wide (yet).
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<2026-05-25 Mon 22:16> I thought I'd post an update since I was able to get full width / page images printing. The previously mentioned width restriction of 96 pixels was due to issues with flow control. While I had enabled XON/XOFF "software" flow control, it didn't seem to be doing anything. I'm not sure if this is because software flow control is actually handled by the driver / device, or if I am supposed to handle it myself. Well, that's what I did. I just keep an eye out for XON and XOFF characters. Prints great now. I also bought some new cartridges for it, but I'd like to try refilling one at some point.
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Comments and feedback are welcome by email (aaron@nospam-aaronsplace.co.uk).