Bill,
The Invertek unit that has failed, has a multi pin power module for the output devices. The remainder of the circuitry is fairly straight forward, there’s a TNY device for the power supply, numerous 8 pin ‘op amp ‘ looking devices and an ARM processor….Repairing is not for the faint hearted, there’s a main board with 2 more boards slotted into it…these need removing to better access….
With the lack of a circuit diag. Repair is hopeless….hence the new purchase..