I reported earlier that my desktop fails to bring up the standby 5V supply after all power being off for a while, i.e., no AC to the box. I have various data points on this: AC off overnight, AC off for 1.5Hr, AC off for a few minutes. The corresponding times for the standby 5V to come up were 10 minutes, 5 minutes, <1-2 seconds. (These times are not very consistent.)
The symptoms during a failure are the voltage rises to 4.12V, then drops quickly to about 1.72V, then drops more slowly (~2V/sec) to about 880 mV, whereupon this repeats with a rep rate of about 580 msec. Upon recovery it rises quickly to 5V and stays there. The main question has been what hardware is likely the cause. This happens with ALL things disconnected from the MB except the memory, the processor, and the processor fan. It was suggested that I replace the PS with a bench supply to the standby 5V and measure the current. When I did this I raised the standby voltage gradually so as to avoid frying something, since I do not know whether the PS or the MB is responsible for the limiting exhibited by the voltage cycling. The symptoms did not repeat with the external supply. V/I pairs were 2.86/88, 3.13/130, 4/223, 5/225 (volts/mA). This is after 15 hours of no AC. The PS has a standby 5V rating of 2.5A. After this last bench supply test, the PS was reconnected and AC applied (still nothing connected to the MB). It took 15 minutes for the pulsing standby voltage to end. My conclusion from this is that the PS is the culprit. Certainly this is what I want to blame rather than the MB. Any suggestions/comments? -Denis _______________________________________________ PLUG mailing list PLUG@lists.pdxlinux.org http://lists.pdxlinux.org/mailman/listinfo/plug
