On Sun, Jun 1, 2014 at 9:30 AM, Galen Seitz <[email protected]> wrote: > On 06/01/14 08:07, Denis Heidtmann wrote: > ... >> My focus now is on the intrusion detection system. The pins are >> jumpered and always have been. Suppose the jumper contacts are noisy >> or the circuit that is designed to detect and record an intrusion is >> faulty. I do not know how the system is designed to react to an >> intrusion event. My only observation is that occasionally (sometimes >> every few days, other times it will go a month or more between events) >> I get a message at boot and a halt. It always is corrected by a >> shutdown and power up sequence. (I do not understand how this behavior >> would protect anybody who wants to implement the feature.) So I >> wonder if when the machine refused to start the intrusion system was >> involved in some way. Ideas? (I still want to replace the battery, >> but am a little gun-shy.) > > If you haven't already, I would replace the jumper with a different one. > I doubt it will help, but it's easy to try. (BTW, long ago I spent a > couple of hours one day at Tek chasing an odd problem. I had a board > plugged into a backplane, and it wasn't getting the interrupts from > another board. The backplane had jumpers to pass along the interrupt > signals for slots which were not occupied. After much head scratching, > I discovered that one of the jumpers was missing the metal contact inside.) > > If you really want to debug this, I'd put an ammeter across the two > intrusion pins and note the current. I'm just guessing regarding the > circuit, but I'd expect to see at least 70 uA (3.3V / 47K). You could > leave it connected for a while and see how the current changes, > particularly with temperature. Again a guess, but I suspect you have a > marginal solder joint that might improve with increased temperature. > > galen > -- > Galen Seitz > [email protected]
Interesting ideas. I have not noticed a correlation between the intrusion incidents and the temperature, but if I can manage to get my ammeter connected I will try it. I wish I could find out how the intrusion detection scheme is supposed to behave. If a ram thief wanted to be undetected and the behavior I see was what was intended a simple power button press erases the intrusion message. Dumb. -Denis _______________________________________________ PLUG mailing list [email protected] http://lists.pdxlinux.org/mailman/listinfo/plug
