the old trouble shooting tricks still work!

[KL7OF]

I was talking to Roy KA7NGT the other nite on 160 and he was telling me how he found some wiring problems in his wife's car by opening the hood and looking at the running engine AFTER DARK.... The leaks are obvious in the dark... My Dad used this trick on the farm equipment when I was a kid..I was working on an EICO 460 scope today and I could see some instability and arcing action on the picture tube but I couldn't find any problems by troubleshooting via the resistance and voltage charts..when I thought about Dad ....I turned out the lights and the problem became evident instantly....A carbon track had developed across the face of the voltage regulator tube socket and had a great little light show going...in the dark....Thanks Dad ..

[W2JBL]

   at my job i deal with the latest high tech DSP/software driven two way radio stuff on the planet, yet i still find more problems with a magnifier and my eyes than any other method. look! it's broken! of course beyond the obvious it just goes in the dumpster and gets replaced. back to the old ways though, last summer myself and Joe N2YR were up at my Adirondack outpost with a broken RME-45. no audio output.
lacking a 'scope i used my old Western Electric buttset coupled through a .01 cap for audio, or 1N34 for RF/IF to trace the problem. when we got done i noticed the old Eico 'scope on the desk next to the station and wondered why i forgot to use it for the job... beer must have clouded my judgement but it sure was fun doing it bare bones!

[W1RKW]

Over the years of troubleshooting I came to the realization that physical inspection (eyes, ears, nose, touch, haven't tried taste yet) will yield a problem more often than using test instruments.

I had a similar problem with my truck. I couldn't figure it out though I had a feeling it was an ignition problem. The truck every once in a while would stumble for no reason at all especially under hard acceleration then it would go away about as fast as it appeared.  Got a hunch one day and figured I'd pop the hood and look at the wires in the dark while the engine was running.  Sure enough found one plug wire with a very slight arc to a valve cover.  Replaced the wires and it ran perfectly from that point on. 

Something recently, at work we had a switching power supply crap out on a simulator.  The guy in charge of the simulator wanted to replace the supply. The caveat was it would take about a month to get a replacement.  I wanted to repair it which would take a couple of days but the guy in charge didn't want to be bothered and would rather spend $600.00 of taxpayers money.  Over the holiday shutdown I said screw this and took the supply home and repaired it for $9.00.  Turned out a be a poorly heatsinked MOSFET that self destructed.  Found this because it wasn't clamped down properly. Simple visual inspection revealed the problem

[Steve - WB3HUZ]

Reminds me a of a story told by an ex Airforce tech who used to work for me. He was in charge of the maintenance of a 10 kW HF transmitter. The TX kept shutting off (protection circuitry doing its thing) and no one could figure out the problem. This guy made a large plexiglass shield, opened the back of the TX and placed the shield between himself and the TX. Then he directed others to turn out the lights and fire up the TX. He was able to observe the source of the problem close up - some HV arcing that would immediately shut down the TX. He had it fixed within five minutes.

[WA1GFZ]

Don't spread this kind of stuff around too  much. Us wizards could be replaced with teams of bean counters.