@Harvey
Left the lab for the day, but I did check the voltage drop across that resistor R624 0.33ohm. I can't recall what it was off the top of my head, but I'll let you know tomorrow. I thoroughly tested both power supply circuits on the SG503 and if there is an issue, it must be something loading down the supplies like you suggest.
However, I injected ~5.2V into the unit with an external power supply - it did not fix the display issue. No difference whatsoever. It may be that these are the normal voltages for the unit when it is powered from a TM5000 series mainframe.
I'll be taking another look at it tomorrow! Grateful for any further suggestions as well!
-Frank
-Frank
Frank Mashockie