Hi, When I watched Birt's excellent video about the Tech Bulletin 100:01 that fixes RS232 voltage levels: https://www.youtube.com/watch?v=KPFnwv_nDD8 ... I finally knew why my RS232 was unreliable and how to fix it.
In my schematic transcript of the M100 I aim to add additional information for anyone working on that machine, so there are a few more annotations explaining things of what to look out for. I've now also updated the transcript to point to that bulletin in the RS232 corner of the schematic, so that anyone who comes across it can quickly see that there is a bulletin and verify with their machine. PDF: https://github.com/hzeller/trs80-100-schematic/raw/main/trs80-100.pdf github: https://github.com/hzeller/trs80-100-schematic If there are any other things that you'd like me to add in annotations that you came across in your repairs, let me know. Cheers, ' Henner.
