You've probably had this happen. Rehearsal and run through went smoothly, all systems appear to be go. Then, just before the service starts, something appears wonky. You see signal present LEDs lighting up on channels that shouldn't be. There isn't signal where the should be. The presentation computer doesn't seem to be acting right. The lights don't respond. What's happening? Sometimes, it's just equipment failure. In that case, you can troubleshoot as quickly as you can, fix it or switch to plan B. Other times, it's a symptom of "What's this button do?" syndrome. Let me explain.
We techies tend to be a naturally curious lot. That's what makes us good at what we do. On the other hand, sometimes that curiosity gets us in trouble. Remember Curious George? We can be like that. I was thinking of this a few weeks ago. We started producing our videos with dialog on one channel and music and effects (M/E) on the other. Simple enough. That way we can better control the mix in the sanctuary, where it can be hard to hear dialog.
Normally, we run our video's audio feed into a stereo input on the M7. This works fine until you want to adjust the relative balance between the two input channels. There's no way to do it. So, we patched it up to channels 40 & 41. No problem. Works great. Then between run through and doors open, our engineer decided it would be more convenient (and less of a reach) to patch it down to 38 & 39. Makes sense, we're not using those for anything, and they're a little closer to where he stands. The problem was gain. Those channels had been used for mics previously, so the gain was turned way up. When we routed a +4 line level signal into them, we had huge amounts of noise. Fortunately, he noticed it, and called me on the com before we ran any video.
Doors hadn't opened yet, so we did some quick troubleshooting. I checked the audio interface, it was good. I checked the switcher, all clear. I re-booted the computer (you never know...). No change. Finally, I looked at Studio Manager running on my laptop in the tech booth. I saw the gain knob set to 3 O'Clock. "Well there's your problem," I said. He dialed the gain back, everything was fine.
Thankfully, he caught it and we were able to fix it before the opening video ran. If we hadn't, we may have had speaker components leaving their home and coming to rest in someone's lap.
I've been guilty of things like this in the past, too. During the sermon, I occasionally get bored and start thinking, "Hmm, how would it work if we did..." That can be dangerous. On more than on occasion, I've had to say to the entire congregation, "That was me..." It can happen with the presentation computer, the light board, sound, whatever. If it has knobs and switches, it's easy to fiddle. And when we fiddle, bad things can happen. That is, unless we follow The Rule.
Don't change things once rehearsal/run-through is over. Unless you know exactly what you are doing, and exactly what the outcome will be, without question, leave it alone. And even then, you're taking a risk.You can try it between services if you have time to test, but in general, once doors open, we're done. That means no re-patching, no clicking on new icons in ProPresenter (those things just seem to show up every time there's an update!), no checking to see what this button does on the light board.
Once you know everything is working, leave it alone! I say this to my team, and I say this to myself. There are so many things that can go wrong when you start changing things, it's just not worth it. What I try to do now is write down the experiments I want to try and play with it during the week. I've been using a program called Evernote for that purpose. I run it on my iPod Touch, my MacBook Pro and my Mac Pro. It keeps my notes in sync, so I can always remember what I was thinking of doing on Sunday.
You can also try a few things during rehearsal; just be aware that if you mess something up, you could be wasting a lot of people's time while you recover. So use that freedom judiciously. Follow The Rule and you'll look smarter and more capable to the people around you. Experiment during the week and bring your learnings out on the weekend, and you'll look smarter still!