Hi,
Tried a stable bench supply in place of the lith bat, got absolutely bugger all from it, wouldn't turn on, didn't do it's Xmas lights display, nowt
left it for a few hours ![Bullshit Detector :bullshit:](https://www.eevblog.com/forum/Smileys/default/BullshitDetector.gif)
Thought I’d buggered it completely.
So i put it all together and it was still as dead as a dodo.
Through curiosity, i connected 5v to the power socket and it came back to life ![WTF? :wtf:](https://www.eevblog.com/forum/Smileys/default/wtf2.gif)
Well, I just forcibly shut down my unit by ripping off the metal cap of an old spring-loaded 4mm plug at work (SKS Hirschmann BUELA - Bueller, Bueller?), which shorted out something. No visible damage, no magic smoke, but wouldn't turn back on. After some investigation I of course ended up here, looking for some schematics around the soft-power-on circuit, but simply connecting it to 5V did the trick. Apparently the unit cannot do a black start with the built-in lithium cell, but instead relies on some aux power to get its control circuit up, and then stays on permanently with extremely low power consumption. Well, it's working just fine again - 2.5V rail for example is 2.4988
8V on calibrated 6½ digit Keysight gear now (not warmed up for three moons!) and was marked as 2.4988
7V at least 10, maybe 15 years ago when I bought it. The badly scratched AD584LH has an 9118 date code...