I'd pose the question "what is really triping the crowbar?" If this is
a repeated problem, perhaps the OVP circuit is getting some RF or a ground
loop from the AC green wire which is causing the rather disasterious
action of tripping the SCR crowbar. My Astron sometimes trips when there
is a thunderstorm and I don't get all the antennas pulled in time.
I doubt the SCR would withstand the energy stored in the filter cap
without some sort of current limiting. Moving the SCR probably save the
pass transistors, but the transistors are cheaper than the diode.
While I've not worked on many of these supplies, I'd guess they are a
bit "wimpy" in every way. Probably needs one more transistor (4 rather
than 3 in parallel) and a more elaborate overcurrent protection circuit.
The Astron OVP trips, the supply gets hot as heck, but when you cycle the
power, all is well.
Ralph Matheny
K8RYU
207 Gibbons Place
Marietta Ohio 45750
"Professionals built the Titanic, amateurs built the Ark"
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