If you are a person of a certain year and have drawn any technical drawings, you are likely to use some kind of R0 ring, whether pencil or pen. Well, r0tring is not just a writing tool. They also made an electronic scriber, a small plotter that can write ISO text on technical drawings according to typed input. It’s a huge time-saving to do it unarmed or template each letter. The cs-50 is designed to save the R0 circle brush at the top of the line, which is the most expensive part of this repair, except for the time spent on sniffing problems.
[atkelar] likes to open things and visually check them before power on. We think this is a good practice, even if suspense will kill you. But in fact, [ATRA] did more than that. He first replaced a coin battery that may have been in the late 1980s, although it was located north of 3V. Then he replaced all the electrolytic caps and a tantalum, cleaned the rubber dome keyboard parts with a cheap electric toothbrush (another good idea), completely disassembled the X-Y mechanism, cleaned and re oiled it.
Then comes the critical moment. Enter the work and display it on the screen, but the stepper does not move. The waveform of the motor looks good, but it seems that the overvoltage is about 3 V. Although [atkelar] could not find the manual on the Internet, he did find a blog post about the machine, which confirmed that the 15 V voltage on the stepper motor was correct.
Facts have proved that this is a basic problem. The sheath of the power cable plays the role of public grounding, so pressing it on the base plate of the removed shell can make the stepper motor work. But after a while, they gave up. [atkelar] cleaned the terminal, but nothing changed – the stepper will work for a period of time and then stop.
We thought it would be a failure this week, but [ATRA] checked more motor pins and found that one of the driver chips was dead. Fortunately, he found a substitute that worked like a new one. Check out the full recovery video after the break to find our favorite parts. At that time [atkelar] built the wall with polyimide tape and filled the cavity with cyanoacrylate glue and baking soda to mold a new screw boss end.
Want to do more repairs? You certainly won’t make mistakes in [dregor’s] works.