If the Pass transistors are getting hot, I would suggest you check across
the positive and negative output leads with the supply unplugged. If you
see Zero Ohms or a Short then it is probably the Crowbar SCR Shorted or
something in that area. Check the voltage going into the control element of
the Crowbar SCR. You could try removing the positive voltage lead from the
Crowbar SCR and firing the supply up for a second to see if the 13.8 volts
is there. It sounds as if you are on the right track. The Pass Transistors
are not getting Hot without reason.
Wade/KJ4WS
On Mon, Feb 4, 2013 at 10:21 PM, Randy Fulco <rfulco@bellsouth.net> wrote:
> The full wave bridge from the transformer is labelled VARO207T. Does
> anyone know what that would sub to? Yes, know many might work, but anyone
> had experience here? The output is shorted, upon turn on- the lamp flashes,
> goes to overload, meter show it drawing 5A, and pass transistors start
> heating up and they would self destruct if left on. Suspect the crow bar
> zener bad, 1N966. Pass transistor both ohm out ok, and both heat up the
> same. Any thoughts?
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