I posted some additional information about my problem as Replies to my original question. I just conclude that was likely the wrong process so I am repeating those posts as a Related Question. Let me know if I am correct or not. Sorry.
The voltage on the FB pin is about 1.8mV with the low mV output voltage with the 50 ohm load connected. It is 0.77V with no load. Don't know if the low FB voltage is a cause or a result of the problem, but everything I know says it is a result as the FB voltage derives directly from the OUT voltage through the resistor divider network. So, this might not be helpful information but though I'd pass it on for completeness. Would the over-voltage lock out or the over current oscillator frequency adjustment, both effected by the FB pin voltage, have anything to do with this?
Another thing: The output voltage sometimes, at least, varies with a steady decrease. When first powered on this morning I got about 3V from the 15V switch setting. About 15 seconds later it had dropped to about 1V. Another 15-30 seconds to about 400mV. Within a minute or two down to a steady 45mV. However I don't notice this every time -- maybe it is there but I simply don't see it, or maybe it is not always there. ?????
The drop on the output voltage is load dependent. With any load greater than 250 ohms to 500 ohms (I can't pinpoint it exactly) the voltage stays precisely on spec. With lesser loads the voltage drops off I suspect linearly -- at around 100 or so ohms the 12v selected output puts out about a steady 4 volts. This means that voltage drop begins at a load current of about 48mA or more [12/250). It doesn't seem that Over Voltage Protection, current limit or short protection current restriction operate in a manner that would cause my problem, but I do not know that for certain. Thoughts?
