The Topward TPS-4000 is a linear bench power supply with two independent adjustable outputs and a third fixed 5V output. It is this 5V output that has failed.

Original schematic (incorrect)

The original schematic seems to be missing the pass transistor and has the other transistors connected in an odd manner which suggested something might not be right.

Reverse engineered schematic (correct)

The transformer/bridge rectifier/filter capacitors have omitted for clarity.

LTspice Simulation

Q2, BD912, would have originally been a 2SA699 transistor.

Failed components – Motorola MJ2955 pass transistor and 2SA1015 sense transistor.

The MJ2955 has a short circuit between the collector & emitter and the 2SA1015 has some odd junction behavior when tested under forward & reverse bias.

I’m waiting for a replacement MJ2955 and the 2SA1015 will be replaced with whatever jellybean transistor I have at hand.