We recently acquired an HP Officejet 7310 with an apparently common fault. The cartridge carrier has some unusual metal springs in it, which are pushed back and alongside the ink cartridge as you insert it, obviously helping to secure it in one way. These springs appear to be held in via small plastic tabs which can break very easily. This allows the spring to come loose and is then pushed back into the fine copper traces on the flexible PCB at the back of the cartridge carrier, ripping through them and causing an error message along the lines of “check right cartridge” (or left, depending on circumstances).
Our customer needed a replacement right away so the only viable option was to replace it with a new unit. This left us with the broken Officejet. It seemed a shame to throw away this otherwise fully working unit, and not being a fan of arguing with foreign tech-support on the phone for hours on end in order to extract a replacement from someone, I decided to try to resolve the problem myself.
In order to access the cartridge carrier, the machine has to be dismantled pretty much entirely. This is not a difficult process but can be quite tricky, as some screws are hard to access with a normal screwdriver. In some cases I used a socket wrench with a torx bit.
Once you’ve got to the cartridges, you then need to devise some way to restore the connections to the broken tracks. I first looked at bridging the tear, but once I saw how small the tracks were, the idea went out the window. The following is what I decided upon:
In order to find wire thin enough, I split a small piece of stranded cable from an old PSU, and used one strand to reconnect each of the disconnected pads back to the PCB itself. The plastic was scraped from the back of the pad and then the wire carefully soldered in to place. The other end was soldered directly to the appropriate pad on the green PCB, traced back from the tear. Each of the wires was then secured with a small piece of electrical tape, to prevent shorts and movement which might break the joint.
It works! It turned out that the 3 or 4 hours it took to do this wasn’t a complete waste of time – the machine now runs again, but for how long?