A while back I picked up an ETC M631 Arbitrary Waveform Generator for $5 at a hamfest. The seller knew it worked, but had not used...
While waiting for parts to arrive to build a proper optical serial interface, I really wanted to get some screenshots off of my oscilloscope. Knowing that the infrared LED in the interface is directly transmitting the serial signal, I figured I should be able to tap into that driving signal to obtain the serial information.
I have a Fluke ScopeMeter 97 that's come in really handy over the years. Before I got it, it was a sales rep's demo unit, so it was used pretty hard. The screen backlight is an electroluminescent panel, and their intensity can fall off pretty dramatically over it's life. This particular display is also transflective, which makes it extremely readable under direct sunlight, but means the backlight is essential to using it in indoor lighting. To use it in the past, I'd shine a bright desk light on it, but I've always wished the backlight would just work.
I have a pair of Acer LCD monitors that I have used since 2006. They were super-cheap when I bought them, but have worked well enough over the years. Some time last year, one of the monitors started having dark lines skittering through the image the entire time it was on. Knowing that it was over 6 years old, I figured one of the backlight tubes was dying and I finally decided to take it apart.
My Dad has a Ford F-150 and has had a misfire problem under part-throttle, mid-power acceleration in the past. The first time, he took it to a mechanic who eventually diagnosed it as a coil failure. He had that one replaced (this engine has a coil on each plug) which fixed the problem, then several months later a second one failed. This one set a code and we were able to figure out which one to replace from the misfire code. This week, he has noticed the same problem creeping back up, but a code wasn't set yet. Using my scan tool, I was able to get the status of the misfire monitors and conclusively determine the cylinder with the issue.