I did the same thing but started with a plc 5 and borrowed the software. I play with electronics because i find it interesting. Repairing boards use to be a lot easier as each chip had a job so you could simply follow the lines and test the components. Now they use a programmable chip its not impossible to trouble shoot but probably not worth the effort.I built a PLC trainer at home, I used a refurb Micrologix 1200 off ebay with an analog card and RsLogix500 starter edition ($149). After 6 months on the road and lugging that thing from hotel to hotel I finally got to where I am comfortable writing small programs. Nothing extravagant. Small presses and forging hammers so far. I guess instead of mastering one thing I am more of a jack of all trades. Hence why I am wanting to dive into electronics. Plus the more I learn about one thing the more I learn how it integrates into everything Ive learned up to that point. I would love to go back to school to formally learn how to program but with two kids my time to them is more valuable.
On some of the older machines we figured out what the control boards did and have backward engineered it so the plc can take over (most were simple timer boards with basic inputs and outputs and the effort was worth it as the parts are nearly impossible to buy)
If you look at the boards that have been repaired you will generally spot where the repairs have been made. you may find that there is a known problem.