The power supply uses dual outputs which are basically the same except for some connections to do specific things like auto parallel or stacking outputs.
The outputs are fully floating and can be stacked up or down. They can also be paralleled because of the auto parallel circuitry.
The unregulated supplies put out about 18V DC on each side. The voltage regulator is done by the 2N5885/2N6124 current drivers controlled by the voltage error amp That amp uses a 2.49V LM336 voltage reference. The VADJ pots allow you to adjust the voltage from zero to 16V. LM358 op amps are used throughout so no negative supply is needed (saves space it's a small chassis it had to fit into).
The voltage amp runs the PS in constant voltage mode unless or until the load current is high enough to reach the value set to the current error amplifier, which also uses a 2.49V reference and pot adjustment to set the current from zero to about 2.7A. Note the current error amp has top priority, because it can take the drive from the output of the voltage error amp. Thus, it forces the voltage down if the current reaches the set value.
The design incorporates thermal shutdown with a transistor glued to the heatsink between the power transistors. U2B shuts the power supply down if the temp gets too high by programming both sides to zero output current. The B side is run through an opto isolator to allow the outputs to be stacked.
The auto parallel mode is used by strapping both negative output terminals together first, then adjusting the B side voltage and current pots to maximum. The A side current is used to provide the reference voltage to the B side current error amp, so it tracks the A side (current shares). By adjusting the B side I ADJ pot, you can have the B side current track the A side in any ratio up to 100% of A side.
There are "CUR LIMIT LED" indicators which show when the current error amplifier has taken control, meaning the PS is in constant current mode. If these are not lit, it is in constant voltage (CV) mode.
There is also an LED to show when auto parallel is engaged.
The total design can be simplified by eliminating auto parallel and thermal shutdown. Any good 2.5V reference can be used such as LM385 or similar.