11/45 - unjustified progress

Well, I dug in to the prints for the RL02 and wrote up notes for myself on all the signals feeding the fault lamp and exactly what pins of what chips they were on (E1 and E2 of the drive logic board). Went downstairs and pushed the BA11-K back into the rack (I had it out to check the ACLO & DCLO signals). I pulled out the RL02 and lifted the logic board and got my notes ready. Instead of a logic probe I decided to use a logic clip. Easier & quicker in this case because I knew just what pins to look at on which chips, and all the signals of interest were on two adjacent chips. I powered up everything including the RX02. When I hit load, the drive spun up and came ready. No fault at all. The RL02 and RX02 both boot & work fine. I've never been quite so disappointed that a system worked, because I know I did nothing to fix it. I tried to recreate the problem all afternoon - with the machine cold, or with it running the instruction set excerciser for hours, no hiccups. The odd part is, the "RL02 faulting upon spinup IFF the RX02 is powered on" WAS completely reproducable, and it never once failed to fail. It failed absolutely 100% of the time for the past few weeks. Not only if it was on when the RL02 spinup was attempted, but if the RX02 was off and the RL02 spun up successfully - the moment you would apply power to the RX02 the RL02 would immediately fault. Now I can't get it to fail, and all I did between times was extend the BA11-K, hook up a probe and look at a few test points, then put it back. Perhaps it is cables. I'll be trying again tomorrow to reproduce the problem and hope it reoccurs :\ Jay