The lamp in an old spectrophotometer went out. The factory repair guy claimed he would fix it in a snap. How? Mysteries of Science
Transcript
A production lab had many kinds of test gear, mainly analytical equipment used to measure incoming raw materials, product intermediates and funnel production lots. Some of the equipment was new, but others looked as if they belonged in a museum.
An old spectrophotometer used a powerful light from a mercury bulb that emitted ultraviolet light. The machine had a big power supply with a transformer, some vacuum tubes, a fan and assorted components.
Every few months the lamp would go out. But this time no one was able to light it again. A new mercury bulb did not fix the problem. The resident factory repair guy, who had been there so long that he knew where every piece of equipment had come from, claimed that he would fix the problem. He was clear that he wasn't going to check the machine, but that he would fix it.
The next morning the spectrophotometer started right up
What did the old repair man do to the machine to fix the problem?
Here's the rest of the story.
After the lab closely examined the unit they spotted a crack in the power supply circuit board. The repair guy had arranged a bolt and screw so that a twist of the screw applied pressure to the circuit board. This apparently applied enough pressure to reconnect the broken circuit connection.
Over time the copper contact area would oxidize until power no longer flowed. Another turn of the screw would flex the board enough to create a proper electrical connection.
Comments
I greatly enjoy your website and your stories, but there's one comment at the end of the tale about the guy that comes in and repeatedly fixes an old piece of gear, but won't let anyone know how he does it, that deserves some comment.
Ultimately, you end the tale with: "Another turn of the screw would flex the board enough to forced contact and a proper electrical connection."
This kind of fix is obviously a bogus "fix" of course, but I wonder how many people reading it will believe that this is just the way you fix intermittent problems? From our experience, trying to sell testing equipment for this problem, most will believe that this is an industry accepted practice... just get it going again any way you can.
In the avionics repair world, this kind of thinking costs the avionics users literally billions of dollars annually in NFF repairs, and is the number one reason things "wear out".
Be careful of what you say... you never know who might be "listening".
