This power on failure issue ended up being a minor repair but it forced me digging into the power supply & voltage safety circuits so I thought to include some of the info I learned while troubleshooting as part 2 and then I will soon make a part 3 about exploring the operations and unique features.

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TIMESTAMPS

1:30 -Power on issue and review of voltage protection circuits

8:35 -Supply voltages after the rectifier

10:00 -Short circuit detected while testing the power transistors

12:00 -Unplugged A2 ribbon cable removed short but power on failed with strange voltages

12:55 -Found tantalum capacitor shorting -15v on main board (cut one end)

13:50 -Found another tantalum capacitor also shorting -15v on Generator board

15:00 -Successful power on with only front panel display board

16:30 -How the voltage regulators track each other and 5v Buck Converter review

19:31 -Current Foldback safety feature in case of short circuit

22:30 -Successful power on with all boards connected (missing 2 filter caps)

23:56 -Compared minor ripples found on -15v to +15v and no real issues

26:20 -Output looks good