Kirk Wallace wrote: > I killed a VAX by spilling coffee in a power strip. Then later, killed > it again, by trying to move a running terminal with my "clever" custom > power cable, which connected the "immortal power" L1 and L2. > Fortunately, the VAX rebooted both times, but the status changes were > recorded on the continuous paper printout. > I had a cobbled-together MicroVAX-II built into a huge old IBM 3rd party memory cabinet. I put this together in 1986, and used it until 2007, although there was only one application left on it. That read environmental sensors scattered around, logged the readings and put some on several LCD displays around the house. Anyway, about 1988, maybe, I was sitting in my old house eating breakfast one morning when there was this loud "snap snap POhhp" from the computer room. I went in and the smell of burning electronics was quite strong. The VAX was rebooting. I had adapted the voltage display panel in that box that monitored voltages and would shut the system down if any supply failed or the temperature sensors detected overheating or fan failure. +5V was normal, but +12 V showed 22.5 V. I thought about it for a half second, but noticed the disk drive sounded "funny" and hit the power off. Well, the power supply I had used had a bunch of extra voltages on it, and I removed some parts from those circuits, not realizing I had defeated the overvoltage crowbar circuit. A transistor failed in the supply, and it went open-loop.
Anyway, the disk drive failed a week later, and I had to replace it. All of 40 MB! The serial ports on the CPU board were popped, but I was able to replace those chips. I went through a number of upgrades on that system, from serial terminal MicroVAX to monochrome Vaxstation to color graphics. Jon ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
