APC SUA1500 Ups problem.
This ups was in the junk pile for a high pitch squeal whenever the unit was plugged in. Found a apparent short at one of the caps near the micro-controller. After de-solder of the suspect cap, the short appeared in the pc board where the component was removed. Traced this back to the micro-controller. After removing the micro-controller the short was gone. The micro-controller is a P87C51FB-4A. I was able to read the program code off the damaged micro-controller and burn it to a new P87C51FB-4A. Installed the new micro-controller and re-soldered the cap. Unit now restored to full working order.
This ups was in the junk pile for a high pitch squeal whenever the unit was plugged in. Found a apparent short at one of the caps near the micro-controller. After de-solder of the suspect cap, the short appeared in the pc board where the component was removed. Traced this back to the micro-controller. After removing the micro-controller the short was gone. The micro-controller is a P87C51FB-4A. I was able to read the program code off the damaged micro-controller and burn it to a new P87C51FB-4A. Installed the new micro-controller and re-soldered the cap. Unit now restored to full working order.

Comment