TI-58 fault - repairable?

[Jeff_Birt]

I cannot find any information about the 'power supply module'. That flat round component looks to be a transformer which causes me to believe this power supply module is a small DC-DC convertor. The transformer getting warm is a sign it is trying to supply more current than it should, likely due to a bad component on the PPCB (a bad IC or perhaps shorted tantalum cap).

There is a note in the service manual that the charger should NOT be plugged in without battery pack present. On many old machines this will cause damage as the battery pack helps regulate the charger voltage. That may have been what has happened in this case.