Your exploding components reminded me of an issue we had with our first surface mount lab. In the Summer we suddenly had a soldering problem in the lab and it turned out that moisture inside the circuit boards was rapidly boiling out of the boards during soldering and blowing the little surface mount parts right off the boards. It looked like someone was blowing compressed air across the boards.
No, I'm sure that removing the outer jacket is the only way to replace the bulb. Besides being a retired electrical engineer, I repaired TVs and later, VCRs for most of my adult life, in addition to my day job, until they got too cheap to repair. I know what I'm talking about.
Here's another moisture/carbon comp story. Back in the mid '70s, I worked for the "batwing" company in South Florida. I was designing what became the first low-cost "consumer" UHF paging receiver; minimizing power consumption was absolutely critical as all we had room for were a pair of N cells. Thus, the logic (custom IC) was implemented in low-voltage CMOS (a new proprietary technology at the time). To keep power consumption down, we used a watch crystal for the clock, with an internal oscillator circuit. I used a 10 megohm carbon comp for the bias resistor across the crystal. Everything worked quite well, and went into production in very high volumes. After the first few runs, we began to have a significant drop in first-pass EOL test yield. After a lot of head-scratching, we found that the oscillator circuit sometimes wouldn't start. The root cause: unfortunately, the factory floor and the stockroom were not climate-controlled, and in South Florida, that meant the humidity was really high most of the time. It turned out that the carbon comps (especially the high-resistance ones) were absorbing moisture, and the "megohm-plus" ones were becoming either "kilohm-plus" (which just increased the current drain) or were exploding when that moisture was turned into steam duing the wave-soldering process! The ultimate fix was requiring all carbon comps to be stored in a climate-controlled area until they would be pulled for immediate insertion and soldering into the PCBs.
Larry M: What I related is a policy that was in place from the 1960s through when I left the company in the latter 1970s. So, while the case you made MAY be technically & scientifically correct, it didn't affect our products which were in widespread use from the North Pole atmosphere to the super-saturated S. American rain forests to the deserts of Africa. The product line consisted of mobile & stationary radio communications equipment, and was found wherever one went, from the NY Harbor to the shores of Tripoli to oil rigs in the North Atlantic to wherever humans inhabited the earth and wanted to communicate with each other. And, since many of these products were the assembly of vacuum tubes AND solid state devices, the heat dissipated by the tubes I'm sure served a very valuable secondary purpose....... demoisturizing the chassis.
The chief engineer was directly responsible for many circuit patents that either he and/or the company held, so I'm sure that IF moisture entrapment was a problem, he would have been very concerned with addressing the issue.
Is it possible that the author has overlooked another way to access the lamp? Perhaps the cover snaps off from inside the oven, but takes more force than he has applied?
We had another Made For Monkeys article about two years ago where that author complained about how difficult it was to clean the filter in his washing machine and boasted about how he had cut a hole in the side of the cover to facilitate its reinstallation.
Another posted pointed out that had he removed the access panel plainly visible at the base of the front panel he would have had easy access to the filter.
Actually, MIL-HDBK-217 (versions B through the current one) point out that using oversized carbon comp resistors degrades reliability. Carbon comp resistors need to run warm to cook off absorbed moisture. If they are oversized their resistance gradually drops as water is absorbed into the carbon, lowering resistance. Bad move on the chief engineer's part.
"There existed a requirement stating that before an individual could move into a new position, he or she had to serve in the current position for at least 18 months. This may sound like a long time but in the design world, you are still considered a "new-be" after 5 years. "
Bobengr, you are right. Every day new technologies and design methodologies are developing, so one should have to be updated it frequently. That's the one reason an engineer seems to be "new be" throughout his career.
Truchard will be presented the award at the 2014 Golden Mousetrap Awards ceremony during the co-located events Pacific Design & Manufacturing, MD&M West, WestPack, PLASTEC West, Electronics West, ATX West, and AeroCon.
In a bid to boost the viability of lithium-based electric car batteries, a team at Lawrence Berkeley National Laboratory has developed a chemistry that could possibly double an EV’s driving range while cutting its battery cost in half.
For industrial control applications, or even a simple assembly line, that machine can go almost 24/7 without a break. But what happens when the task is a little more complex? That’s where the “smart” machine would come in. The smart machine is one that has some simple (or complex in some cases) processing capability to be able to adapt to changing conditions. Such machines are suited for a host of applications, including automotive, aerospace, defense, medical, computers and electronics, telecommunications, consumer goods, and so on. This discussion will examine what’s possible with smart machines, and what tradeoffs need to be made to implement such a solution.