Hi Harvey,
I think you (and Dave before) forget here that the supplies are protected by foldback current limiting. In case of a nearly dead short the current will be much smaller than in normal circumstances, and I guess that also the power dissipation in the series pass transistor will be smaller (the reduced current "wins" from the increased Vce so to speak). The bulk cap voltage will be higher than normal.
Albert
toggle quoted message
Show quoted text
On Sun, Jun 24, 2018 at 08:11 am, Harvey White wrote:
So, look for the bulk voltage, you'll find it to be a bit low. Now
look at the voltage drop on the pass transistor (that's the variable
resistor function). If there's a short on the output (I'd suspect
one), then the transistor drops the whole bulk supply voltage and
should be rather warm. There's a current sense resistor in there, say
0.1 to 2 ohms or so, generally with a transistor base/emitter junction
across it. Look for .5 to .7 volts across this resistor. If so, then
the supply is trying to current limit to protect itself.
