RT2250 Shuts down on its own after a few minutes of regular operation.

I have the same problem and it seems like it is going into thermal shutdown as ICs 104 and 106 are overheating which are fed from C138. All input source voltages seem to be correct and I do not get any voltage fluctuation from any input on the following regulator ICs. IC 106 3.3 VDC regulator is giving me 3.3VDC as a Output Source voltage and IC 104 5VDC regulator is giving me 5.0 VDC. IC102 15VDC regulator is giving 15VDC output and IC103 -15VDC regulator is constantly dropping voltage from the time of "Power On" until shutdown which takes about 5-7 minutes. I get right around -11VDC when shutdown occurs. ICs 102 and 103 are not overheating which leads me to believe that the IC 103 -15VDC regulator is faulty and putting a load on the other regulators which are trying to compensate for the voltage drop. I plan to replace the regulator with an NTE 969 replacement.