I have acquired a very nice XC-540MT that had a possible surge.
Here is what the previous owner has described to me:
"How the problem started:
I was doing a general cleaning.
When I was removing a strap on magenta print head a surge occurred and a spark happened at the strap end in my hand.
The machine printed for a few days though each time the magenta/cyan began to wane in printing color. From there it continued to the black and yellow print heads.
I went through all the check lists, and in my opinion, it would either be the servo board or the mother board. believe mother board was replaced same time as servo in the past."
Can anyone give me some guidance on how to test the motherboard and servo board.
I have a working XC-540 Right next to the XC-540MT so I can swap parts to determine the problem parts. BUT I want to be sure I can do this in a way that won't damage the good boards.
I have a good deal of experience with soldering and have some Fluke meters. I just need to know where to start.
Ok here is an UPDATE!
The XC-540MT has a blown Transistor on the Head board (TR12). I metered all of them to find the faulty one (I did this by checking for a short across any two legs of each transistor)
I replaced the shorted Transistor but I am still getting a very high impedance reading on the new Transistor legs (I tested the new transistor before powering up), this reading is different than every other transistor in the same row as well as every other row (they all have similar readings to each other).
I found a post stating that the capacitors in the same circuit tend to fail at the same time. But I am unsure if I need to replace the small smd ceramic caps on the front and back or the electrolytic cap on the top of the board (or all). I have schematics if it will help anyone make a determination.
Any and all help is greatly appreciate!