The new parts arrived to repair the Topward TPS-4000 power supply I had diagnosed in a previous post.

The Motorola MJ2955 was replaced with a MOSPEC branded part as originals are in short supply and popular with audio amplifier enthusiasts.

The 2SA1015GR was replaced with a BC557C as I have many of these.

Being the inquisitive type, I decided to cut open the old power transistor to see what was inside.

Using a digital microscope I managed to capture significant damage on the silicon.

Completed power supply.