Quoted from Pafasa:
I see your point. The built in diagnostics are a great help. Something that EM machines don't have. For me though, understanding board level circuitry and troubleshooting is the bigger challenge. I can "see" the entire "circuit board" inside and out with an EM. Things are hidden inside chips on modern machines. This is why EM is easier for me. I work better with the mechanical than the electronic.
The pinball master hits the nail on the head. You have to learn what to look for and can almost see the problem in your head. Once you understand the logic almost anything is fixable and usually for a fairly cheap price.
SS points you in the right direction, but you can't truly fix it yourself unless you call swapping out boards and opto devices fixing. And EM is an incrediblty complex computer without the chips.
The guys that designed them were an amazing group.
Now is spotting the problem alway easy. No!! Sometimes it will keep me up at night thinking about the issue, but as long as you can follow the path (or paths) you can usually find the issue. And you have to remember that the problem is often not where you are looking, but at some small little thing that may feed the place where you think the prolem is.
I love working on them and wouldn't have it any other way.
Once you go EM you'll never go back