Why do you suspect that there is damage that needs to be tested for?If you had a robot that stopped functioning, and diagnostics and troubleshooting led you to replace the servo amp, after which it worked, and you want to verify that the servo amp really was the problem, the easiest way is to swap it out in a currently working robot. This is a little risky, as you are plugging a suspected faulty electrical component into a known functional electrical system, and it could cause damage besides itself.
If you have two setting on a tool box, one good and one bad, and need to figure out which is which, the same deal still applies.
If you want to find out exactly WHAT is wrong inside of a known bad servo amp, that is way more complicated, and probably better to ask Fanuc if they would be willing to do diagnostics on it. In general, if you want to do more than test I/O resistance in a complex integrated circuit, you need a lot of specialized equipment and full detailed schematic of the board.
It hasn't been replaced, the robots first axis won't move, tries to but can't. After a lot of diagnoses everything seems to be functioning correctly, after talking with fanuc they suggested the servo amp however there are no alarm codes popping up related to the amp nor are there any alarm leds lighting up on the servo amp so I would like to be positive that's what it is before we purchase a new one. we've checked everything else it could be and we know it's all good. i was simply hoping there might be a way to check it easily without pulling it. I know it was a stretch but i thought asking would be worth a shot.