First a bit of an introduction: I'm a mechanical engineering student in my final semester, with some hobby-level background in electronics. I've found myself an internship of sorts, but I have found myself repairing electronic components, mainly dealing with servomotors and amplifiers. My first project was an ancient (1988) robotic welding arm which came with no documentation, and was not working. I got it working three times. Shutting down for the night messed up something though, and it wouldn't start up again the next day without some fiddling. It finally stopped working once, and the next time it came back online, one of the servos overdrove itself at high speed, rammed into the end of its range, and seems to have damaged the amplifier. That project is on hold.
Second project: A back gauge (made in 1976) for a large press brake (from 1928). The amp was fairly simplistic, and I had a schematic this time. I was able to repair it.
Third project: Another back gauge, slightly newer - 1984. This amp got fried good. The optocoupler appears to have caught fire, and the connector feeding power to the motor got hot enough to melt the solder on the backside.
So, that's the backstory.
Now the reason I'm here: I need a starting point on how to go about repairing servo amps. The real kicker is that I can't always find schematics.
The latest one that has the roasted optocoupler, the components on it could be easily replaced. The problem I see is the testpoints and the trimpots. There are around 15 test points, and 4 trimpots. I assume that I'd need some documentation to know how to adjust those trimpots, and so that I'd know what outputs to look at on those testpoints, much less what piece of equipment to use - a multimeter? An oscilloscope? Is that thinking accurate?
This particular servo amp is on its way to another state for an evaluation, but I'd much rather repair it myself, as 1) It would likely save the company money, 2) I'd like to learn how to repair servo amps myself, and 3) The company's owner is quite keen on me learning something from these projects I am given.
Besides, being a mechanical engineer with a fair amount of electronics experience would probably help with job prospects.
