Why Schottky? I have absolutely no clue. Clearly its wrong.1) why did you use a Schottky diode for this? It has terrible leakage current. A standard rectifier should be used, just like the data sheet shows.
2) Without knowing the full details of the internal circuit of the LM317 it’s hard to say, but my guess is that when you pull ADJ low, the output cap discharges through the diode into your transistor. The block diagram shows a current source in that path, but who knows what that really is?
3) I’m not convinced that pulling ADJ to ground is a good thing, with or without a diode.
Any clues like Q3 E-C short, B-E or B-C short ? Or opens ?
Regards, Dana.
The original ckt ( post #1 ) appears to be wrong - you need a lot more Cin on the LM317 - they show a tendency to fail if the input has lots of ripple.
The Lm317 needs at least 2v5 of headroom - so for 29.5 Vout you need at least 32V in ...
FvM has also pointed out a failure mode that results from not reading the data sheet.
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