On Tuesday, January 17, 2012 10:34:41 PM Ed Nisley did opine: > On Tue, 2012-01-17 at 20:30 -0500, gene heskett wrote: > > If I fix the library, > > will that fix the schematic when it is next loaded? > > Nope, the schematic holds copies of all the components, so that you > can't inadvertently wreck all your circuits with a single library > change. > > You must delete all instances of the old part from the schematic, > refresh the library to get the new part, and then re-place all of them. > > It's a pain, but it does make a certain kind of sense. Yes, I have to agree.
> > those manuals were in my mailbox this evening. > > Excellent! Now, keep telling the occasional war story... Alright, how about this one? Nearly 20 years ago, the transmitter took to throwing some black streaks in the picture, quite intermittently at first but gradually, over a period of 6 months or so it got to the "we can't ignore it any longer" stage. My operators had identified a spot on the front of the driver cubicle where they could occasionally whack with a foot or so of 2x4 & get it to stop, for a little while. I took stuff apart, one stage and one night at a time looking for bad solder joints, re-soldered anything that even remotely looked guilty without bothering it a bit. I finally did a no-no and removed a back window in the cubicle door, waited for it to get started, and took an electric fence fiberglass rod and started poking at anything I could touch from the windows access angle. The driver cabinets 3rd of 4 stages was a pair of 4-1000's running push- pull, driven by an 829-B also working push-pull that for bandwidth purposes has a swamping resistor network to load the circuit slightly, connected from one 4-1000's grid #1 to the other tubes grid, and all hidden in plain sight in a perforated box on the side of the cavity which seemed to be the most sensitive place to prod. Checking the parts lists I saw they were fairly fancy 20 and 50 watt carbon film resistors, painted on ceramic tubes about 1/2 and 5/8" in diameter. And hell to get to, lots of other power and rf plumbing in the way. 829-B's being about a 15 to 20 watt output tube, it had taken a few of them used up and 40 years to damaged those resistors. Finally getting the cover clear, I found them mounted in big fuse clips, so I pried them out & put one in each pocket & headed for the bench where I had some higher powered test gear. Even after all those years, the values were still visible and in fact neither one of them ever looked like they had been hot. Grabbing an ohmmeter I checked from the lead sleeve to lead sleeve used as an end ferrule to a thin ring of gold plate that ran from under the sleeve to under the coating, which looked like bare, baked in place carbon, but which was apparently an insulation coating. One of them was within 10% of the painted on value but the other measured anything from 2 or 3 hundred percent higher all the way to open.. Bingo. We had one of those old electric eye bridge indicating capacitor checkers, so I hooked its 0-600 volt leakage test probes up and the eye went nuts at 20 volts. I turned off the lights and when my eyes became dark adjusted, I could see a faint arcing leaking thru the coating about 1/8" under that coating from the gold plated end band. I came home to get one of my dremels with a couple of those grey rubber abrasive wheels and spent about 4 hours polishing that coating away all the way around that end of the resistor until I had continuity from the far end ferrule to the carbon film all the way around. Then I painted about 3 layers of nickle print on that area to reconnect the ferrule to the carbon film under the coating & let it dry for a while. Then the resistance was within 10% of what was painted on it, so I carefully reinstalled it and got it on the air about 9 AM, loooong night. I put the window back in the next Friday night, my normal night to kick its tires. Why didn't I just order new copies of one or both? Real simple, the machinery that made those resistors at IRC was thrown in a ditch in FL in about 1970, a good many years before I called to check. So they were rather effectively made out of our favorite material, pure unobtainium. You do what you have to do when its your responsibility to do so. Any other Chief Engineer on this side of the planet would have told the owner the only cure was a new, $150k transmitter. But I fix things. It was still working ALMOST normally when we turned it off for the last time June 30, 2008. The reason I say almost was that the last batch of 4 new 4-1000's tubes I had bought, came from an air force base in germany that had declared them surplus in 1996, new ones had been discontinued by Eimac 10+ years before that. AFAIK, those were the last 4 NOS tubes on the planet. So I put in some powerstats so I could turn the heaters down about 20% when they were fresh & made those last 4 tubes last 14 years. Normal life was about 6 months. Now you know why I occasionally make the remark that guys like me are a dying breed, because the new ones 2-3 generations after me have no clue about this stuff, it is just useless trivia to them. By the same reasoning, they probably can deal with today's stuff better than I, witness my startup pains with eagle. All in all though, I think I've had a mostly good ride. And with everyone's help on this list, my so called Golden Years (yeah, right) have been a blast, thanks to all who have been tempted to bitch slap the old man but haven't. I appreciate it, a lot. I assume that when the mailing list address changes, we'll have a few hours warning? FWIW, I too have tangled with EMC's legal dept, pushing 40 years ago, but they have been around a lot longer than our emc has been, so it was a matter of time I guess. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> With a rubber duck, one's never alone. -- "The Hitchhiker's Guide to the Galaxy" ------------------------------------------------------------------------------ Keep Your Developer Skills Current with LearnDevNow! 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