On Troubleshooting

I think troubleshooting is a distinct skill that is technology independent. For example, Annie just called me in to the living room because the TV was displaying "No Signal", despite the fact that we were successfully watching TV earlier in the day. I don't really know anything about TVs and DVRs and tuners beyond "you plug the cables in where they fit", so I was slightly concerned. However, all my years of troubleshooting software bugs came through. Here was my process:

1. Sanity check: make sure all cables are plugged into the right ports and the TV is set to the right setting. Still not working.
2. Sanity check: turn off and on DVR and TV. Still not working.
3. Move HDMI cable from port 1 to port 2 on TV, then port 3. Still not working.
4. Get new HDMI cable from basement and test DVR and TV. Still not working.
5. Test laptop HDMI into ports 1, 2, and 3 on TV. Laptop output to TV not working. 
6. Unplug power from TV, wait 10 seconds, plug back in. Eureka! It's working!

The trick is to continually isolate a single factor and remove that factor from consideration. If I had not tried the laptop, I doubt I ever would have figured out the problem. But I needed to test with an input other than the DVR to isolate the DVR and TV from each other to determine which was the problem. I'm just glad I was able to fix the TV so easily.