oldcomputerexpert
Member
I know Bitsavers.org has part one of the service manual for the 810, but part 2 of the service manual that has the troubleshooting and schematics is missing. There is a complete service manual for an 820, however it's completely different from the 810. I'm restoring my 810 I have had in storage for 40 years. I think it worked back then but now when powering up the head starts to move then shuts down with an error. The power supply voltages look good and the print head moves freely so it's not jamming. The transistors that drive the carriage servo motor look good. I have traced out the motor position encoder feedback to the processor board but have not yet checked for a signal. Hopefully someone has part 2 of the service manual. It will make the repair much easier.