[cctalk] Re: Another 780 backplane story

While not on a 780 back plane, about 50 years ago, I was basically in charge of some 26 PDP16M computers. Periodically, one of the chips would be found with the top blown off. At some point, I pulled the computer and examined the backplane filled with wirewrap wires. The solution turned out to be fairly simple... a -15V bus was about .001" near one of the wirewrap posts. A slight moving of that bus away from the wirewrap post solved that problem. I have to assume it was a temperature related problem since increasing that spacing solved the problem. Unrelated to the computer problem, another source of angst was intermittently one of those computers would crash. That one took probably a year to find... one of the interface M series pullup cards had a pulldown card installed in its place. I should mention all the above took place on a newly install system. Marvin