Wanted to follow up, since I hate it when people pop onto a forum, post for help, go back and forth for a day or two, then disappear.
First off, I learned a very... no, I already knew better, I had reinforced for me a very important lesson about about unplugging or plugging things in which carry voltage, when the power to the machine is on*. I work on tube amps a lot. I know better. Almost always, I get hurried or cocky or both, and make a mistake. Sometimes, there isn't any consequence except a momentary scare, and sometimes a shock to remind me. Other times, like this one, there are consequences. Potentially very bad ones.
Second, Steve Sadler is. The. Man. There may be nobody on the planet who knows as much about MCI machines as Steve does. And he is very, very patient. In a half hour Skype session, he was able to walk me through several troubleshooting steps, which ultimately resulted in finding, and fixing, for the cost of a 3A fuse (and Steve's time, which was totally worth it), the problem that had:
- made all of my VU meter lights inoperative,
- as well as all of the input lights on the meter, bridge,
- the record ready LEDs on my Autolocator III stop lighting, and,
- as it turned out, the VU meters weren't even registering signal in input mode.**
I also, in the course of that 30 minutes, learned a f7ck of a lot about how these machines work, what the power supplies and connectors are supposed to be doing, and a lot about my specific machine. If you are, like me, a DIY wannabe tech, the proverbial "knows enough to get myself into trouble, but not out" guy, working on a machine which is way beyond your depth, someone like Steve is a god-send. I can not recommend his service enough. If you're lucky enough to be such a skilled guy yourself, or have one locally upon whom you can call - on a Sunday, no less, consider yourself blessed. If the above is not true, someone like Steve is indispensable.
So, what turned out to be the problem? Steve led me through a series of steps, in a very specific order, then had me slide out the channel 1-8 drawer, and measure the fuses at the bottom, both of which are 3A fuses intended to supply 24VDC each. One of them was blown. (By the way, never discount something stupid and simple like a bad alligator clip lead screwing you up. Suspect every piece of gear if something doesn't make sense). By the way, I had previously "checked" that fuse by seeing if there was continuity across it. There was. What there wasn't, was 24V at both ends like there was supposed to be.
So, I'm back to where I was before I started swapping lamps out live. And I will never, ever do that again.
*Unless someone like Steve tells you to do it. And make sure you listen and understand instructions before you act. One of the first things Steve asked me to do was to unplug the Tuchel connectors from the meter bridge. With the power on. At other points, like when he had me pull the three connectors from the top of the power supply, and when I plugged them back in, he had me power the machine off.
**I had missed this detail until I was in the process of getting things ready to talk to Steve today. The meters showed when something was playing back, and they registered incoming and outgoing signal when recording, but not when the machine was sitting idle in Input mode.
After getting that all working again, I very carefully put back every cover I had removed, rolled the machine very gingerly back into place, and backed away, slowly.
BTW, on a personal note, speaking to Steve reminded me a lot of my grandfather, who taught me how to do a lot of things when I was kid. Very patient, and very literal. He had, at various points in his career, trained machinists and technicians at John Deere in the 50's and 60's, and pilots during WWII. He understood the value of teaching a man to fish, rather than catching them for him, but some days, it's okay to clue them in on what the fish are biting on that day. And he was very much of the philosophy of letting people learn from mistakes, as long as they didn't get themselves or someone else killed. One of his favorite tricks, when training anyone, was to give them a set of instructions, and tell them to read the entire thing, beginning to end, before starting. I'm sure most of you know where this is going. When a student would come to him, stuck on a problem, and say they had followed the directions and still screwed up, his first question was whether they had actually read _all of the instructions first_. Invariably, the last instruction would be something along the lines of, "Do not perform step 6."