We would have started at the DAC after we had checked the power supply rails...
The T503 IN- looks pretty poor anyhow - when compared to T503 IN+ so I would still look at why. There may still be a power supply fault lurking.
This is the problem with jumping to swapping components. You have not followed a logical diagnostic process to arrive at that conclusion - so do not learn how to find faults. You just learn to ask others and swap parts.
When your skills improve, then you will learn which components fail more often for yourself, and then you can take short cuts.
I have another problem, if i insert the diagnostic cart and i turn on the console, i see the first screen but after some seconds, the screen came black...if i run the console with integrated minestorm, i have not problem..