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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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USB port blew -- why?
One of the ports of my NEC-based USB 2.0 card quit working because the
National Semiconductor LM3526 power controller chip failed. I'm pretty sure that I didn't zap it with static (I always touch the outher metal shell to the computer case before plugging it in) or try to plug it in backwards. The data sheet for the LM3526 says that it's protected against voltage, current, and even temperature, so what happened? National Semiconductor says that each USB port must have a 120uF or larger tantalum capacitor between +5V and ground for protection against transients that occur during hot-plugging, and NEC's example schematic for their uPD720100A USB 2.0 chip shows the LM3526 using 150uF aluminum in parallel with 0.1uF ceramic. But my USB card has only a 100uF aluminum capacitor and maybe a ceramic capacitor in parallel for this. Could this be why the USB port got zapped? Would it help to solder a tantalum in parallel as well? Will it hurt to add it? |
#2
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"larrymoencurly" wrote in message om... .... | National Semiconductor says that each USB port must have a 120uF or | larger ....................................... But my USB card has | only a 100uF aluminum capacitor and maybe a ceramic capacitor in | parallel for this.... Close enough! N |
#3
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On Mon, 04 Oct 2004 01:50:54 GMT, "NSM" wrote:
"larrymoencurly" wrote in message . com... ... | National Semiconductor says that each USB port must have a 120uF or | larger ....................................... But my USB card has | only a 100uF aluminum capacitor and maybe a ceramic capacitor in | parallel for this.... Close enough! Except the tantalum cap would have much lower esl & esr figures than an aluminum cap, making it more effective. otoh, tantalums can have a brilliant failure mode ;-) |
#4
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"larrymoencurly" wrote in message om... One of the ports of my NEC-based USB 2.0 card quit working because the National Semiconductor LM3526 power controller chip failed. I'm pretty sure that I didn't zap it with static (I always touch the outher metal shell to the computer case before plugging it in) or try to plug it in backwards. The data sheet for the LM3526 says that it's protected against voltage, current, and even temperature, so what happened? Stuff just fails occasionally with no good explaination, could be it was just a defective part that eventually quit. |
#5
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"James Sweet" wrote in message news:lu58d.2427$r3.597@trnddc05... | | "larrymoencurly" wrote in message | om... | One of the ports of my NEC-based USB 2.0 card quit working because the | National Semiconductor LM3526 power controller chip failed. I'm | pretty sure that I didn't zap it with static (I always touch the | outher metal shell to the computer case before plugging it in) or try | to plug it in backwards. The data sheet for the LM3526 says that it's | protected against voltage, current, and even temperature, so what | happened? | | | Stuff just fails occasionally with no good explaination, could be it was | just a defective part that eventually quit. Or as I say, "Everything works until it breaks". Then there are the three brand new tubes I took off the shelf one at a time, each of which was bad. Still can't get over that one. N |
#6
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NSM wrote:
"James Sweet" wrote in message news:lu58d.2427$r3.597@trnddc05... | | "larrymoencurly" wrote in message | om... | One of the ports of my NEC-based USB 2.0 card quit working because the | National Semiconductor LM3526 power controller chip failed. I'm | pretty sure that I didn't zap it with static (I always touch the | outher metal shell to the computer case before plugging it in) or try | to plug it in backwards. The data sheet for the LM3526 says that it's | protected against voltage, current, and even temperature, so what | happened? | | | Stuff just fails occasionally with no good explaination, could be it was | just a defective part that eventually quit. Or as I say, "Everything works until it breaks". HEY!! That's MY line. Then there are the three brand new tubes I took off the shelf one at a time, each of which was bad. Still can't get over that one. Find the guy who put the defective ones back on the shelf g. N |
#7
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"James Sweet" wrote in message news:lu58d.2427$r3.597@trnddc05...
Stuff just fails occasionally with no good explaination, could be it was just a defective part that eventually quit. I am eternally grateful for your answer, which not only completely solved my problem with the USB port but will also magically turn the rest of my life into bliss. So please give me your address so that I can send you a $500 check, no, make that a blank check -- your advice was that good. |
#8
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#9
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On Mon, 04 Oct 2004 03:21:58 +0000, daytripper wrote:
On Mon, 04 Oct 2004 01:50:54 GMT, "NSM" wrote: "larrymoencurly" wrote in message .com... ... | National Semiconductor says that each USB port must have a 120uF or | larger ....................................... But my USB card has | only a 100uF aluminum capacitor and maybe a ceramic capacitor in | parallel for this.... Close enough! Except the tantalum cap would have much lower esl & esr figures than an aluminum cap, making it more effective. otoh, tantalums can have a brilliant failure mode ;-) So do engineers when they're bringing up a system where all of the tantallums were inserted backwards. You want to see fireworks! (well,it was 25 years ago - I've mostly recovered and the tinninus isn't so bad. twitch) -- Keith |
#10
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keith wrote:
On Mon, 04 Oct 2004 03:21:58 +0000, daytripper wrote: On Mon, 04 Oct 2004 01:50:54 GMT, "NSM" wrote: "larrymoencurly" wrote in message e.com... ... | National Semiconductor says that each USB port must have a 120uF or | larger ....................................... But my USB card has | only a 100uF aluminum capacitor and maybe a ceramic capacitor in | parallel for this.... Close enough! Except the tantalum cap would have much lower esl & esr figures than an aluminum cap, making it more effective. otoh, tantalums can have a brilliant failure mode ;-) So do engineers when they're bringing up a system where all of the tantallums were inserted backwards. You want to see fireworks! (well,it was 25 years ago - I've mostly recovered and the tinninus isn't so bad. twitch) LOL. Yeah, I'll bet. You get a similar result plugging non keyed circuit boards into a vertical card rack 180 degrees reversed. |
#11
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"keith" wrote in message news | So do engineers when they're bringing up a system where all | of the tantallums were inserted backwards. You want to see fireworks! | (well,it was 25 years ago - I've mostly recovered and the tinninus | isn't so bad. twitch) I recall being told of a large TTL circuit board which was powered up with reverse polarity. This was noticed due to the considerable amount of heat being given off. Everyone was mystified when the correctly rewired board worked OK. I guess TTL is a little more tolerant than is generally believed. N |
#12
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forgive me for not immediately recommending you open the controller chip and
place it under your scanning electron microscope to search for signs of electromigration... "larrymoencurly" wrote in message om... "James Sweet" wrote in message news:lu58d.2427$r3.597@trnddc05... Stuff just fails occasionally with no good explaination, could be it was just a defective part that eventually quit. I am eternally grateful for your answer, which not only completely solved my problem with the USB port but will also magically turn the rest of my life into bliss. So please give me your address so that I can send you a $500 check, no, make that a blank check -- your advice was that good. |
#13
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"larrymoencurly" wrote in message om... "James Sweet" wrote in message news:lu58d.2427$r3.597@trnddc05... Stuff just fails occasionally with no good explaination, could be it was just a defective part that eventually quit. I am eternally grateful for your answer, which not only completely solved my problem with the USB port but will also magically turn the rest of my life into bliss. So please give me your address so that I can send you a $500 check, no, make that a blank check -- your advice was that good. Just what sort of answer did you expect? I seem to have misplaced my crystal ball and I can't find my spell book either. How is anyone supposed to tell you why a chip failed? It just happens. |
#14
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"larrymoencurly" wrote in message om... | "James Sweet" wrote in message news:lu58d.2427$r3.597@trnddc05... | | Stuff just fails occasionally with no good explaination, could be | it was just a defective part that eventually quit. | | I am eternally grateful for your answer, which not only completely | solved my problem with the USB port but will also magically turn the | rest of my life into bliss. So please give me your address so that I | can send you a $500 check, no, make that a blank check -- your advice | was that good. Assuming you are being sarcastic (it's not clear), I refer to this as a CatRan question, i.e., "I was typing away on my computer and I was holding the keyboard above my head and I was watching the screen through my toes when all of a sudden the cat ran over my stomach and I noticed the screen blinked twice. What causes that"? N |
#15
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On Mon, 04 Oct 2004 22:33:31 -0500, David Maynard wrote:
keith wrote: On Mon, 04 Oct 2004 03:21:58 +0000, daytripper wrote: On Mon, 04 Oct 2004 01:50:54 GMT, "NSM" wrote: "larrymoencurly" wrote in message le.com... ... | National Semiconductor says that each USB port must have a 120uF or | larger ....................................... But my USB card has | only a 100uF aluminum capacitor and maybe a ceramic capacitor in | parallel for this.... Close enough! Except the tantalum cap would have much lower esl & esr figures than an aluminum cap, making it more effective. otoh, tantalums can have a brilliant failure mode ;-) So do engineers when they're bringing up a system where all of the tantallums were inserted backwards. You want to see fireworks! (well,it was 25 years ago - I've mostly recovered and the tinninus isn't so bad. twitch) LOL. Yeah, I'll bet. You get a similar result plugging non keyed circuit boards into a vertical card rack 180 degrees reversed. A good reason to hang the mechanical designers by the short things. One *should* have to go to great lengths to pluch dangerous things in backwards. In this case they did just that. ...and even complained about how hard it was! -- Keith |
#16
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On Tue, 05 Oct 2004 03:47:13 +0000, NSM wrote:
"keith" wrote in message news | So do engineers when they're bringing up a system where all | of the tantallums were inserted backwards. You want to see fireworks! | (well,it was 25 years ago - I've mostly recovered and the tinninus | isn't so bad. twitch) I recall being told of a large TTL circuit board which was powered up with reverse polarity. This was noticed due to the considerable amount of heat being given off. Everyone was mystified when the correctly rewired board worked OK. I guess TTL is a little more tolerant than is generally believed. TTL protection diodes are as strong as moose! Unless the chips got hot enough to let the magic smoke out, they'll likely survive, though perhaps somewhat injured. -- Keith |
#17
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keith wrote:
On Mon, 04 Oct 2004 22:33:31 -0500, David Maynard wrote: keith wrote: On Mon, 04 Oct 2004 03:21:58 +0000, daytripper wrote: On Mon, 04 Oct 2004 01:50:54 GMT, "NSM" wrote: "larrymoencurly" wrote in message gle.com... ... | National Semiconductor says that each USB port must have a 120uF or | larger ....................................... But my USB card has | only a 100uF aluminum capacitor and maybe a ceramic capacitor in | parallel for this.... Close enough! Except the tantalum cap would have much lower esl & esr figures than an aluminum cap, making it more effective. otoh, tantalums can have a brilliant failure mode ;-) So do engineers when they're bringing up a system where all of the tantallums were inserted backwards. You want to see fireworks! (well,it was 25 years ago - I've mostly recovered and the tinninus isn't so bad. twitch) LOL. Yeah, I'll bet. You get a similar result plugging non keyed circuit boards into a vertical card rack 180 degrees reversed. A good reason to hang the mechanical designers by the short things. One *should* have to go to great lengths to pluch dangerous things in backwards. In this case they did just that. ...and even complained about how hard it was! Hehe. Well, with the one I mentioned it was an experimental prototype built by the design engineer. |
#18
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"NSM" wrote in news:sgI8d.14605$MV5.538@clgrps13:
"larrymoencurly" wrote in message om... | "James Sweet" wrote in message news:lu58d.2427$r3.597@trnddc05... | | Stuff just fails occasionally with no good explaination, could be | it was just a defective part that eventually quit. | | I am eternally grateful for your answer, which not only completely | solved my problem with the USB port but will also magically turn the | rest of my life into bliss. So please give me your address so that I | can send you a $500 check, no, make that a blank check -- your advice | was that good. Assuming you are being sarcastic (it's not clear), I refer to this as a CatRan question, i.e., "I was typing away on my computer and I was holding the keyboard above my head and I was watching the screen through my toes when all of a sudden the cat ran over my stomach and I noticed the screen blinked twice. What causes that"? N Reminds me of the time an aquaintance went to lunch with me and a few of the other engineers. He was in a rather "know it all" mood. I started plying him with questions about how water softeners work, what causes gravity, etc. He was doing good until I asked him, "Ever wake up on a wednesday and think it was tuesday all day and then wake up the next day and everything is ok again? What is that called?" He shut up after that. r -- Nothing beats the bandwidth of a station wagon filled with DLT tapes. |
#19
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Kibo informs me that keith stated that:
On Tue, 05 Oct 2004 03:47:13 +0000, NSM wrote: "keith" wrote in message news | So do engineers when they're bringing up a system where all | of the tantallums were inserted backwards. You want to see fireworks! | (well,it was 25 years ago - I've mostly recovered and the tinninus | isn't so bad. twitch) grin They don't smell too good either. I recall being told of a large TTL circuit board which was powered up with reverse polarity. This was noticed due to the considerable amount of heat being given off. Everyone was mystified when the correctly rewired board worked OK. I guess TTL is a little more tolerant than is generally believed. TTL protection diodes are as strong as moose! Well, the individual diodes aren't all that strong, but there's one on every single I/O pin on every chip, so on a big PCB, the load will be spread over a *lot* of diodes. Unless the chips got hot enough to let the magic smoke out, they'll likely survive, though perhaps somewhat injured. Yup. The best I've personally seen was the time I accidentally plugged a 2716 EPROM backwards into a programmer. It lit up like a xmas tree through the UV window, but worked fine when I turned it around the right way. -- W . | ,. w , "Some people are alive only because \|/ \|/ it is illegal to kill them." Perna condita delenda est ---^----^--------------------------------------------------------------- |
#20
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Rich.Andrews wrote:
Reminds me of the time an aquaintance went to lunch with me and a few of the other engineers. He was in a rather "know it all" mood. I started plying him with questions about how water softeners work, what causes gravity, etc. He was doing good until I asked him, "Ever wake up on a wednesday and think it was tuesday all day and then wake up the next day and everything is ok again? What is that called?" He shut up after that. Groundhog day? |
#21
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"Rich.Andrews" wrote in message .1...
Assuming you are being sarcastic (it's not clear), The "" always means non-hostile sarcasm. I refer to this as a CatRan question, i.e., "I was typing away on my computer and I was holding the keyboard above my head and I was watching the screen through my toes when all of a sudden the cat ran over my stomach and I noticed the screen blinked twice. What causes that"? I think that it's more like, why did the waterproof flashlight suddenly stop working when it started to rain? |
#22
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On Tue, 05 Oct 2004 23:09:32 -0500, David Maynard wrote:
keith wrote: On Mon, 04 Oct 2004 22:33:31 -0500, David Maynard wrote: keith wrote: On Mon, 04 Oct 2004 03:21:58 +0000, daytripper wrote: On Mon, 04 Oct 2004 01:50:54 GMT, "NSM" wrote: "larrymoencurly" wrote in message ogle.com... ... | National Semiconductor says that each USB port must have a 120uF or | larger ....................................... But my USB card has | only a 100uF aluminum capacitor and maybe a ceramic capacitor in | parallel for this.... Close enough! Except the tantalum cap would have much lower esl & esr figures than an aluminum cap, making it more effective. otoh, tantalums can have a brilliant failure mode ;-) So do engineers when they're bringing up a system where all of the tantallums were inserted backwards. You want to see fireworks! (well,it was 25 years ago - I've mostly recovered and the tinninus isn't so bad. twitch) LOL. Yeah, I'll bet. You get a similar result plugging non keyed circuit boards into a vertical card rack 180 degrees reversed. A good reason to hang the mechanical designers by the short things. One *should* have to go to great lengths to pluch dangerous things in backwards. In this case they did just that. ...and even complained about how hard it was! Hehe. Well, with the one I mentioned it was an experimental prototype built by the design engineer. ....even this design engineer knows how to key a connector. ;-) -- Keith |
#23
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On Wed, 06 Oct 2004 15:56:56 +1000, Lionel wrote:
Kibo informs me that keith stated that: On Tue, 05 Oct 2004 03:47:13 +0000, NSM wrote: "keith" wrote in message news | So do engineers when they're bringing up a system where all | of the tantallums were inserted backwards. You want to see fireworks! | (well,it was 25 years ago - I've mostly recovered and the tinninus | isn't so bad. twitch) grin They don't smell too good either. Hot electricity never smells good. ...ever notice that? ;-) I recall being told of a large TTL circuit board which was powered up with reverse polarity. This was noticed due to the considerable amount of heat being given off. Everyone was mystified when the correctly rewired board worked OK. I guess TTL is a little more tolerant than is generally believed. TTL protection diodes are as strong as moose! Well, the individual diodes aren't all that strong, but there's one on every single I/O pin on every chip, so on a big PCB, the load will be spread over a *lot* of diodes. I've pumped several amps though individual ones, but you're right with thousands in parallel it's tough to smoke 'em. It *can* be done, but... Unless the chips got hot enough to let the magic smoke out, they'll likely survive, though perhaps somewhat injured. Yup. The best I've personally seen was the time I accidentally plugged a 2716 EPROM backwards into a programmer. It lit up like a xmas tree through the UV window, but worked fine when I turned it around the right way. Oh, my! I've never done that. However... One time back in the '60s (when I was a mere lad playing with electronics) a friend and I were talking about these new-fangled LED thingys. He said they were no big deal and had them for some time. He then took a small-signal glass-encapsulated diode from his pile-o-parts, bent the leads about 3/4" apart and grabbed it with long-nosed pliers. He then shoved it into the mains outlet and sure enough it lit up, and quite brightly too! He did make some comment about his reliability problems, or some such. I just about PMP. ;-) -- Keith |
#24
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keith wrote:
On Tue, 05 Oct 2004 23:09:32 -0500, David Maynard wrote: keith wrote: On Mon, 04 Oct 2004 22:33:31 -0500, David Maynard wrote: keith wrote: On Mon, 04 Oct 2004 03:21:58 +0000, daytripper wrote: On Mon, 04 Oct 2004 01:50:54 GMT, "NSM" wrote: "larrymoencurly" wrote in message oogle.com... ... | National Semiconductor says that each USB port must have a 120uF or | larger ....................................... But my USB card has | only a 100uF aluminum capacitor and maybe a ceramic capacitor in | parallel for this.... Close enough! Except the tantalum cap would have much lower esl & esr figures than an aluminum cap, making it more effective. otoh, tantalums can have a brilliant failure mode ;-) So do engineers when they're bringing up a system where all of the tantallums were inserted backwards. You want to see fireworks! (well,it was 25 years ago - I've mostly recovered and the tinninus isn't so bad. twitch) LOL. Yeah, I'll bet. You get a similar result plugging non keyed circuit boards into a vertical card rack 180 degrees reversed. A good reason to hang the mechanical designers by the short things. One *should* have to go to great lengths to pluch dangerous things in backwards. In this case they did just that. ...and even complained about how hard it was! Hehe. Well, with the one I mentioned it was an experimental prototype built by the design engineer. ...even this design engineer knows how to key a connector. ;-) Hehe. I bet that one does too... NOW |
#25
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keith wrote:
On Wed, 06 Oct 2004 15:56:56 +1000, Lionel wrote: Kibo informs me that keith stated that: On Tue, 05 Oct 2004 03:47:13 +0000, NSM wrote: "keith" wrote in message news | So do engineers when they're bringing up a system where all | of the tantallums were inserted backwards. You want to see fireworks! | (well,it was 25 years ago - I've mostly recovered and the tinninus | isn't so bad. twitch) grin They don't smell too good either. Hot electricity never smells good. ...ever notice that? ;-) I recall being told of a large TTL circuit board which was powered up with reverse polarity. This was noticed due to the considerable amount of heat being given off. Everyone was mystified when the correctly rewired board worked OK. I guess TTL is a little more tolerant than is generally believed. TTL protection diodes are as strong as moose! Well, the individual diodes aren't all that strong, but there's one on every single I/O pin on every chip, so on a big PCB, the load will be spread over a *lot* of diodes. I've pumped several amps though individual ones, but you're right with thousands in parallel it's tough to smoke 'em. It *can* be done, but... Unless the chips got hot enough to let the magic smoke out, they'll likely survive, though perhaps somewhat injured. Yup. The best I've personally seen was the time I accidentally plugged a 2716 EPROM backwards into a programmer. It lit up like a xmas tree through the UV window, but worked fine when I turned it around the right way. Oh, my! I've never done that. However... One time back in the '60s (when I was a mere lad playing with electronics) a friend and I were talking about these new-fangled LED thingys. He said they were no big deal and had them for some time. He then took a small-signal glass-encapsulated diode from his pile-o-parts, bent the leads about 3/4" apart and grabbed it with long-nosed pliers. He then shoved it into the mains outlet and sure enough it lit up, and quite brightly too! He did make some comment about his reliability problems, or some such. I just about PMP. ;-) A bit on the high side with power consumption too, I'll wager. hehe |
#26
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what main board? FIC ECS MSI?...usb blew cause the board blows.
"larrymoencurly" wrote in message om... One of the ports of my NEC-based USB 2.0 card quit working because the National Semiconductor LM3526 power controller chip failed. I'm pretty sure that I didn't zap it with static (I always touch the outher metal shell to the computer case before plugging it in) or try to plug it in backwards. The data sheet for the LM3526 says that it's protected against voltage, current, and even temperature, so what happened? National Semiconductor says that each USB port must have a 120uF or larger tantalum capacitor between +5V and ground for protection against transients that occur during hot-plugging, and NEC's example schematic for their uPD720100A USB 2.0 chip shows the LM3526 using 150uF aluminum in parallel with 0.1uF ceramic. But my USB card has only a 100uF aluminum capacitor and maybe a ceramic capacitor in parallel for this. Could this be why the USB port got zapped? Would it help to solder a tantalum in parallel as well? Will it hurt to add it? |
#27
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"JAD" wrote in message ...
"larrymoencurly" wrote in message om... One of the ports of my NEC-based USB 2.0 card quit working because the National Semiconductor LM3526 power controller chip failed. I'm pretty sure that I didn't zap it with static or try to plug it in backwards. The data sheet for the LM3526 says that it's protected against voltage, current, and even temperature, so what happened? National Semiconductor says that each USB port must have a 120uF or larger tantalum capacitor between +5V and ground for protection against transients that occur during hot-plugging, and NEC's example schematic for their uPD720100A USB 2.0 chip shows the LM3526 using 150uF aluminum in parallel with 0.1uF ceramic. But my USB card has only a 100uF aluminum capacitor and maybe a ceramic capacitor in parallel for this. Could this be why the USB port got zapped? Would it help to solder a tantalum in parallel as well? Will it hurt? what main board? FIC ECS MSI?...usb blew cause the board blows. My main boards are cheap, FIC and ECS, so any built-in USB for them uses an SiS or VIA chip. My NEC USB is a PCI card. But why couldn't any built-in USB blow out because of something off the main board? I had a built-in RS-232 serial port blow because someone tried to hot plug a parallel printer port (vaporized a couple of tiny capacitors used by the RS-232-TTL converter chip), no other damage. |
#28
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In comp.sys.ibm.pc.hardware.chips keith wrote:
glass-encapsulated diode from his pile-o-parts, bent the leads about 3/4" apart and grabbed it with long-nosed pliers. He then shoved it into the mains outlet and sure enough it lit up, and quite brightly too! He did make some comment about his reliability problems, or some such. I just about PMP. ;-) Well, OK. But now traffic engineers are installing LED traffic light replacement bulbs specifically _for_ reliability? Daisy chain a dozen or so LEDs all facing one way, and plug it in. Face another set the other way. Parallel as many as you need for brightness. Nicely vibration resistant. -- Robert |
#29
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"JAD" top posted:
reliability and power consumption,,,,,,,,,,,,,,,, speaking of street lights I was reading yesterday that a number a US cities are being investigated about their manipulation of the traffic signals to burn more gas, thus creating revenue for the city, (gas city level taxes) Right. And OJ isn't guilty. |
#30
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huh?
he is guilty (whatever connection there is to that) and so are the cities involved in the lighting scam......\ or are you saying that its impossible? very naive...but it was a side note and not meant for debate. "chrisv" wrote in message ... "JAD" top posted: reliability and power consumption,,,,,,,,,,,,,,,, speaking of street lights I was reading yesterday that a number a US cities are being investigated about their manipulation of the traffic signals to burn more gas, thus creating revenue for the city, (gas city level taxes) Right. And OJ isn't guilty. |
#31
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keith wrote in
news One time back in the '60s (when I was a mere lad playing with electronics) a friend and I were talking about these new-fangled LED thingys. He said they were no big deal and had them for some time. He then took a small-signal glass-encapsulated diode from his pile-o-parts, bent the leads about 3/4" apart and grabbed it with long-nosed pliers. He then shoved it into the mains outlet and sure enough it lit up, and quite brightly too! I once had a bizarre failure of a USR modem immediately after a thunderstorm. You would think it would be a typical frying of the phone circuits etc. When I checked it out, the relay coil was open circuit. This of course is on the control cctry and not the telecom side. I replaced the relay and it worked perfectly. Can only assume it was a coincidence since if it was a voltage surge it should have taken out the semis on the relay drive. |
#32
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Robert Redelmeier wrote:
In comp.sys.ibm.pc.hardware.chips keith wrote: glass-encapsulated diode from his pile-o-parts, bent the leads about 3/4" apart and grabbed it with long-nosed pliers. He then shoved it into the mains outlet and sure enough it lit up, and quite brightly too! He did make some comment about his reliability problems, or some such. I just about PMP. ;-) Well, OK. But now traffic engineers are installing LED traffic light replacement bulbs specifically _for_ reliability? You missed the 'joke'. It wasn't an 'LED', it was a 'diode' raised to catastrophic incandescence from being fried to hell and back. Of course, one *could* call it a 'light emitting diode', for a few milliseconds, but it hardly works on the same principle. Daisy chain a dozen or so LEDs all facing one way, and plug it in. Face another set the other way. Parallel as many as you need for brightness. Nicely vibration resistant. -- Robert |
#33
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On Wed, 06 Oct 2004 23:50:49 -0500, David Maynard wrote:
keith wrote: On Wed, 06 Oct 2004 15:56:56 +1000, Lionel wrote: Kibo informs me that keith stated that: On Tue, 05 Oct 2004 03:47:13 +0000, NSM wrote: "keith" wrote in message news | So do engineers when they're bringing up a system where all | of the tantallums were inserted backwards. You want to see fireworks! | (well,it was 25 years ago - I've mostly recovered and the tinninus | isn't so bad. twitch) grin They don't smell too good either. Hot electricity never smells good. ...ever notice that? ;-) I recall being told of a large TTL circuit board which was powered up with reverse polarity. This was noticed due to the considerable amount of heat being given off. Everyone was mystified when the correctly rewired board worked OK. I guess TTL is a little more tolerant than is generally believed. TTL protection diodes are as strong as moose! Well, the individual diodes aren't all that strong, but there's one on every single I/O pin on every chip, so on a big PCB, the load will be spread over a *lot* of diodes. I've pumped several amps though individual ones, but you're right with thousands in parallel it's tough to smoke 'em. It *can* be done, but... Unless the chips got hot enough to let the magic smoke out, they'll likely survive, though perhaps somewhat injured. Yup. The best I've personally seen was the time I accidentally plugged a 2716 EPROM backwards into a programmer. It lit up like a xmas tree through the UV window, but worked fine when I turned it around the right way. Oh, my! I've never done that. However... One time back in the '60s (when I was a mere lad playing with electronics) a friend and I were talking about these new-fangled LED thingys. He said they were no big deal and had them for some time. He then took a small-signal glass-encapsulated diode from his pile-o-parts, bent the leads about 3/4" apart and grabbed it with long-nosed pliers. He then shoved it into the mains outlet and sure enough it lit up, and quite brightly too! He did make some comment about his reliability problems, or some such. I just about PMP. ;-) A bit on the high side with power consumption too, I'll wager. hehe Given the temperature, it was likely more efficient than the average incandescent bulb. ;-) -- Keith |
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On Thu, 07 Oct 2004 12:27:08 +0000, Robert Redelmeier wrote:
In comp.sys.ibm.pc.hardware.chips keith wrote: glass-encapsulated diode from his pile-o-parts, bent the leads about 3/4" apart and grabbed it with long-nosed pliers. He then shoved it into the mains outlet and sure enough it lit up, and quite brightly too! He did make some comment about his reliability problems, or some such. I just about PMP. ;-) Well, OK. But now traffic engineers are installing LED traffic light replacement bulbs specifically _for_ reliability? They're more efficient too. LEDs are a few times more efficeint and the monochromatic light is particularly suited for traffic lights. OTOH, in the '60s... Also note that some cars are using LEDs for tail lights. Headlights are still a bit of a problem. Daisy chain a dozen or so LEDs all facing one way, and plug it in. Face another set the other way. Parallel as many as you need for brightness. Nicely vibration resistant. Hmm, face another set the other way and you can plug 'em into AC. I thought these things were a tad more specialized than that though. -- Keith |
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On Thu, 07 Oct 2004 08:19:53 -0700, JAD wrote:
reliability and power consumption,,,,,,,,,,,,,,,, speaking of street lights I was reading yesterday that a number a US cities are being investigated about their manipulation of the traffic signals to burn more gas, thus creating revenue for the city, (gas city level taxes) I thought that was all about red-light cameras (a real scam!). -- Keith |
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On Thu, 07 Oct 2004 19:39:18 -0500, David Maynard wrote:
Robert Redelmeier wrote: In comp.sys.ibm.pc.hardware.chips keith wrote: glass-encapsulated diode from his pile-o-parts, bent the leads about 3/4" apart and grabbed it with long-nosed pliers. He then shoved it into the mains outlet and sure enough it lit up, and quite brightly too! He did make some comment about his reliability problems, or some such. I just about PMP. ;-) Well, OK. But now traffic engineers are installing LED traffic light replacement bulbs specifically _for_ reliability? You missed the 'joke'. It wasn't an 'LED', it was a 'diode' raised to catastrophic incandescence from being fried to hell and back. Of course, one *could* call it a 'light emitting diode', for a few milliseconds, but it hardly works on the same principle. I'm quite sure Robert got it. He knows my silliness well (though may not admit it snip -- Keith |
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"Geoff C" wrote in message ... keith wrote in news One time back in the '60s (when I was a mere lad playing with electronics) a friend and I were talking about these new-fangled LED thingys. He said they were no big deal and had them for some time. He then took a small-signal glass-encapsulated diode from his pile-o-parts, bent the leads about 3/4" apart and grabbed it with long-nosed pliers. He then shoved it into the mains outlet and sure enough it lit up, and quite brightly too! I once had a bizarre failure of a USR modem immediately after a thunderstorm. You would think it would be a typical frying of the phone circuits etc. When I checked it out, the relay coil was open circuit. This of course is on the control cctry and not the telecom side. I replaced the relay and it worked perfectly. Can only assume it was a coincidence since if it was a voltage surge it should have taken out the semis on the relay drive. Lightning can cause some very bizarre failures indeed. I had a USR modem years ago that failed after a nearby lightning strike (rare here) and the problem turned out to be a 10 ohm surface mount resistor with a crater in it. Replaced it with a normal resistor and it worked fine until it was retired years later. |
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"James Sweet" wrote in message news:jcp9d.5644$eq1.2343@trnddc08... | Lightning can cause some very bizarre failures indeed. I had a USR modem | years ago that failed after a nearby lightning strike (rare here) and the | problem turned out to be a 10 ohm surface mount resistor with a crater in | it. Replaced it with a normal resistor and it worked fine until it was | retired years later. What most people think is caused by lightning is really caused by induction. A direct lightning strike will turn your computer etc. into a pile of bubbling slag. A strike near the phone line causing induction elsewhere will zap things in very odd ways. N |
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In comp.sys.ibm.pc.hardware.chips keith wrote:
I'm quite sure Robert got it. He knows my silliness well Entirely too well! I'm convinced you were either trying to demonstrate prior art or "obvious to a skilled practioner in the art" to invalidate the LED patent, and show the general silliness of most patents. (though may not admit it Why not play the straight man? -- Robert |
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On Fri, 08 Oct 2004 17:13:19 +0000, Robert Redelmeier wrote:
In comp.sys.ibm.pc.hardware.chips keith wrote: I'm quite sure Robert got it. He knows my silliness well Entirely too well! I'm convinced you were either trying to demonstrate prior art or "obvious to a skilled practioner in the art" to invalidate the LED patent, and show the general silliness of most patents. Naw, just busting chops. I would *never* demonstrate such! I have such "silliness" and a few more in the pipe. It's a profitable endeavor. ;-) (though may not admit it Why not play the straight man? Ok, perhaps I will some day! ;-) -- Keith |
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