A coworker threw a 9V battery in the trash in his van once and the contacts shorted and started a fire. He wraps them in tape now (and that's why I do too now, always)
I once bought a Harbor Freight (parodied as Hazard Fraught -- google it) 12 volt drill for twenty bucks.
Its major flaw other than just general quality was that when you removed the battery, the battery contacts were exposed. One time when I took off from a client, I smelled something and saw smoke in my rear-view. Smoke inside the van. I pulled over and found a steel tool had come in contact with both battery terminals. The battery was almost too hot to touch. It wouldn't fit any more. But hey, I still had the second battery. (And I learned to put my tools away a little better.)
Months later, I went to a ranch in northern Arizona, flying into Phoenix and driving from there, to do some work. I took my tools, including that drill, in a suitcase. With the battery attached. No problem.
But when I arrived back in LA, the suitcase was not in baggage claim. They couldn't find it. I went to the office and they said if they found it they'd bring it to my home. Ok.
Four hours later a courier shows up with the suitcase. Cool. The drill was in it along with the other tools. And HOLY CRAP!
Some bright-ass TSA agent in Phoenix had checked the drill by removing the battery and did not put it back together. He'd handled some of the tools, too, and left them. Loose. In the suitcase. Near the battery. The battery with the exposed terminals.
The entire plane was lucky to have made it to LA.
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
I've been using the Ideal VDV for years and I'm quite happy with it for general toning and mapping of cables that are dissconected at both ends.
I also have a Fluke IntellaTone Pro that I use for LIVE network mapping! [Link: amazon.com]
It paid for itself in time savings the first time I used it in a commercial setting where the server room was in the basement and I was working on the 10th floor!
Every day is a good day.......some are just better than others!
Proud to say that my property is protected by a high speed wireless device!
I got my coworker's wand today so I could take it apart and attempt to figure out what went wrong with it, why it caught fire. It looks to me like the capacitor immediately in line after the power supply burned up. It's not even there anymore. Of course it could have come off and fallen somewhere after failing, but maybe it just melted? I don't know, I'm not an electrical engineer of any sort. The wires from the battery connector, I can see that traces in the circuit board go straight to that capacitor. It's a...well, I think, at least...a multi-layer ceramic capacitor. At first I was thinking that maybe it had an in and out side like an electrolytic capacitor and that the "out" side had failed, causing too much power buildup and heat that caused it to catch fire. I did a little research and found that this type of capacitor can develop cracks and short itself out after too many power cycles. There appears to be no damage in line after that capacitor. It doesn't look like there was initially a short in the positive and negative wires coming from the 9V battery, so I think the reason that the picture I have of it with the connector (where you plug the battery in, sorry if my terminology isn't great) smoking was caused, ultimately, by a problem with that capacitor. If there is anyone here with this kind of circuitry knowledge I'd love to hear what you think.
If you guys watch AVE (highly recommend if you don’t) on YouTube you will understand why something like this caught fire. You will also learn through many of his tear downs why you buy once cry once. The chineseum components in a lot of today’s tools and gadgets are downright scary.
Yo man thanks for sharing, I've watched some videos and plan on watching a lot more. That's good info. I'm always appreciative when people provide valuable sources for advice, demonstration, and education.
It’s possible that the unit will still work without that capacitor.
Here is one failure mode of batteries: As batteries age their internal impedance rises. You can think of this as a theoretical ideal battery that will maintain its voltage, regardless of current draw, with a series resistor between this ideal battery and the external terminals. As the battery ages, the value of this resistor increases and there is a higher and higher voltage drop across this resistor. Eventually, this internal impedance is so high that the battery is useless.
The capacitor that you describe is often added to store some energy and help maintain voltage for the following circuit. This is helpful if there are short demand peaks by the circuit that cannot be supported directly by the battery. Energy stored in the capacitor will support the peak demand and the capacitor will recharge after a while.
Without the capacitor it is possible that the unit will operate with a fresh battery, but may become flaky after the battery ages slightly.
If this is an electrolytic capacitor, I’ve seen them “blow up” with a flash and some smoke, leaving only two stubs of wire on the circuit board. However, if one looks around, one can usually find the hollow aluminum shell. It’s possible that the markings on this shell are still intact, and you’ll be able to buy a replacement. Be sure to get the polarity correct when you install the new capacitor, or you’ll have another “event” in a little while.
If there is anyone here with this kind of circuitry knowledge I'd love to hear what you think.
I didn't go back and read the whole thread, so this might be a repeat. What brand and model? As a bonus, do you have a URL for a schematic?
I've never heard of this kind of failure with a ceramic capacitor. That, of course, proves nothing. (This subject reminds me of a cartoon from the 60s where a guy is asking for a ceramic capacitator and a selenimum rectalfire.)
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
On February 8, 2019 at 14:55, Ernie Gilman said...
And we all should absorb the lesson that the little CR2032 stores A LOT of power. We're used to thinking of it as a low current device because it's used that way for its long life.
Put a couple of those in your pocket among the quarters and dimes!
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
There is no clear origin to this phrase. In the 1700's, it was just used as "burning your pocket," but by the 1800's it had become "burning a hole in your pocket." The implication is that the coins are so hot that you jerk them out of your pocket and throw them away.
This tower of intellectual accuracy continues with
How did money originate? Answer Ug gave his friend Org a pretty rock in exchange for a bite of Org's apple. Org later exchanged the rock for a bite of Iggy's rabbit. The following day, Iggy's wife found the rock and used it to buy a purse. Iggy would spend the rest of his days making sure the purse has new pretty rocks in
and soon asks us, giving a punch line to this whole subject,
Where did money originated from?
I swear that's a copy and paste.
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
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