- PC Smoke Chapter 2 - 6 Updates
- Cap testing question - 9 Updates
- Leaving small devices on constantly. - 6 Updates
- Phone listening stops working - 3 Updates
- PC Smoke - 1 Update
| OG <freenews@freenewsspam.net>: May 06 11:02AM -0700 So, after the long discussion on smoke detectors I thought it best to start a new post hole. I opened the case and looked at the board. It is a so called military grade MSI ATX motherboard. I saw no charred anything. But I did see pieces of charred something sitting on the board and looked upwards and discovered a cable hanging loose. Look closely at the end of the cable and saw what was left of a drive power connector. Traced that to the power input to a Hitachi 2T HDD. What that my C: drive (Win 7) ? Yikes! I have four 2T drives in there. Thank goodness I just backed up the C: drive using Macrium Reflect Free to an external USB Drive. Anyway, now I am wondering if the power supply was taken out. It is a 600W CoolerMaster RS-500-PCAR. Do these protect themselves or just melt down with the connector. The cabling is hard ot get to since the PC is packed tight with 4 HHD and two DVDs and a few boards plugged into the motherboard. So maybe the connector contact was not so good and the resistance increased to a point where the connector melted the shorted out? The connector was melted AND also turned to dust. Connector went bad or ? Wonder if the drive is still good. Got to take it out and have a good look. Thoughts (other than smoke detectors). --- news://freenews.netfront.net/ - complaints: news@netfront.net --- |
| Paul <nospam@needed.com>: May 06 03:44PM -0400 OG wrote: > Wonder if the drive is still good. > Got to take it out and have a good look. > Thoughts (other than smoke detectors). I would not trust the connectors now. That means replacing the power supply. If, on the other hand, the connector was a SATA Y-cable or a SATA extension, maybe that was the defective part, and the power supply doesn't have a quality issue. If the power supply connector end burned, you cannot use that drive again. The contacts on the drive end, will be heat-damaged and degraded, and will encourage the connector on a new supply, to fail in exactly the same way. You may be able to connect the drive long enough to clone it, but I would no longer trust it. When the connector is new, the metal is nice and shiny and conductive. After an overheat issue, the metal is oxidized, heat stressed, and has a higher resistance. Replacing both ends of the connector system, is required to return things to mint condition. And that's why you shouldn't use that hard drive again. If you do want to use the hard drive again, you can use an extension cord. When it burns the extension cord, there would be no damage to the new power supply. PSU ----- Molex to SATA ---- ---- - - - Bad drive ^ | +--- Will burn here... So if it were to burn again, just the middle (extension cable) would need to be replaced. It all depends on whether you like the smell of "resistor smoke", as to whether that is a practical alternative (isolates the damage a bit better). The second time it fails, will be for potentially different reasons than the first time, due to the heat damage to the drive end power contacts. You can easily solder a pigtail to the hard drive, to power it in place of the SATA 15 pin. So even if you didn't have backups, you may be able to get the data off it. It would require locating where +5V, +12V, GND, GND are on the controller board, to tap in and connect a Molex pig tail as a replacement. I did that to replace a burned end connector on a video card and it held up fine. ******* One suggestion here is "tin whiskers". A metallurgy problem. You cannot use pure tin on assemblies, because a thin spike of material will "grow" between conductors. The whisker grows between conductors, until it shorts them out. https://community.spiceworks.com/topic/824148-sata-adapter-burnt-and-melted-smell-bad We had some special RAM modules we designed at work. The first ones, were made with gold all over the place. At the time, gold wasn't nearly as expensive as it is now. Anyway, in the spirit of cost-reduction, the next generation (same form factor), they decided it would be fun to make them with tin in place of the gold. And apparently, the person who did that, had never heard of tin whiskers. And pretty well exactly one year to the day, each module would fail, as a whisker would grow across the surface of the substrate. We used to run an Xacto knife between tracks, to cut the whiskers, but they would only grow back again. Making the RAM modules a write-off. The substrate in this case was ceramic, so these were not even remotely close to modern DIMMs or SIMMs in design. A thorough understanding of metallurgy is required for anyone doing this sort of design work (i.e. don't ask me to do it :-) ) Metallurgy affects lots of stuff. When you see electrical contacts on things, they consist of a number of layers of plating. The materials and order of layering is determined by safe metallurgy. So you could use tin, if it was combined with the correct other materials. So someone knows what metal mixture, plate up, or whatever, will stop whiskers. There's no need for whiskers in electronics in 2016. This is "all known stuff". You shouldn't be designing connectors and cables, unless you know this stuff. Paul |
| hrhofmann@att.net: May 06 01:30PM -0700 What Paul says (+1) |
| Paul in Houston TX <Paul@Houston.Texas>: May 06 08:52PM -0500 OG wrote: > Do these protect themselves or just melt down with the connector. > The cabling is hard ot get to since the PC is packed tight with 4 HHD and two DVDs and a > few boards plugged into the motherboard. IMO, 600w and cooling is not nearly enough for what you have that machine doing. This machine has a 750w p/s and sometimes it gets stressed. 2-4 hdds, 1-2 dvds, various cards, etc. cpu fan, hdd fan, 2 bridge fans, ram fan, pwr sup fan, gpu fan, all set to max. Everything overclocked. 24" floor fan on the side of the case. When the current p/s goes bad I'll get a 1 kw p/s. |
| philo <philo@privacy.net>: May 06 09:42PM -0500 On 05/06/2016 08:52 PM, Paul in Houston TX wrote: > to max. > Everything overclocked. 24" floor fan on the side of the case. > When the current p/s goes bad I'll get a 1 kw p/s. The total power of the supply is irrelevant as to the connector that burned. The supply only delivers what is called for. More than likely the connector was not pushed in all the way, when the drive was installed. Otherwise it was loose pins |
| Paul in Houston TX <Paul@Houston.Texas>: May 06 10:48PM -0500 philo wrote: > only delivers what is called for. > More than likely the connector was not pushed in all the way, when the drive was installed. > Otherwise it was loose pins Yea, I agree. Should have made that clear in my post. |
| etpm@whidbey.com: May 06 12:05PM -0700 I have a computer that won't turn on unless it is warm enough. The problem is in the power supply. If I use a blow drier to blow some warm air through the exhaust holes in the power supply for a minute or two the power supply starts working. I was told by someone here or on the basics group that there is probably a bad electrolytic capacitor causing the problem. I also have a CNC machine that has a servo amp that acts the same. The machine must be on for a while and when the cabinet that holds the servo amps gets warm enough inside the amp start working and will work fine as long as the machine is kept powered up. If the machine is turned off for an hour or so and then powered back up the amp still works. But if the machine is off overnight the amp acts the same as above. I replaced the amp so there is no problem running the machine but I would like to repair this amp so I can have a spare on the shelf. Anyway, it has only 3 physically large electrolytic caps. I unsoldered one lead from each cap and measured the capacitance with my Extech multimeter. The two 10 uf caps measured 11. something uf and the 33 uf cap measured 37. something. Could these caps be bad anyway? There are also three blue colored dipped caps that have printed on them: .068K 250. I don't what the dot in the .068K means but I don't think it's a decimal point. Maybe it means lead free. There are also a couple 47 uf wound polymer caps. Could either of these types of caps need to be warm before they work properly? I have no schematic for this amp and have not been able to get one. Furthermore, the company that makes this servo amp has ground the markings off of any device with more than three leads. Thanks, Eric |
| ohger1s@gmail.com: May 06 12:14PM -0700 > the markings off of any device with more than three leads. > Thanks, > Eric Yes, caps that read good value can still be bad. Most electrolytics that are bad will show high ESR readings (bad) before they show low capacitance. ESR meters are cheap enough that anyone who screws with electronics should have one. Despite the advice of others, I always remove the capacitor to test ESR with an "in-circuit" ESR tester. Also, a good percentage of wonky electrolytics will show signs of venting at the top of the cap, if not an actual electrolyte leakage, then a discernible bulge. If you see any bulged caps, change them. Most small disc and film caps will not become temperature sensitive. For a device to be warm up sensitive like your device it's usually a weak electrolytic , so concentrate there. If there's only a few electrolytics, change them all with good quality (I like Panasonic) caps and they'll probably run. |
| Randy Day <randy.day@sasktel.netx>: May 06 02:10PM -0600 In article <t2opiblcf3u910hulv3na3u5haf4a3ackr@4ax.com>, etpm@whidbey.com says... > I have a computer that won't turn on unless it is warm enough. The > problem is in the power supply. If I use a blow drier to blow some Bad caps are certainly one possibility, but there are other things to check for as well. There could be a cold solder joint that makes contact when a lead expands with heat. A connector may have a bit of corrosion that slips away when the metal contacts slide past each other under heating. Try disconnecting and reseating all connectors. Intermittent issues like these can be a pain to diagnose... --- news://freenews.netfront.net/ - complaints: news@netfront.net --- |
| Ralph Mowery <rmowery28146@earthlink.net>: May 06 04:21PM -0400 In article <4e956b9c-7245-474d-adf7-012b51bb3989@googlegroups.com>, ohger1s@gmail.com says... > Also, a good percentage of wonky electrolytics will show signs of venting at the top of the cap, if not an actual electrolyte leakage, then a discernible bulge. If you see any bulged caps, change them. > Most small disc and film caps will not become temperature sensitive. For a device to be warm up sensitive like your device it's usually a weak electrolytic , so concentrate there. > If there's only a few electrolytics, change them all with good quality (I like Panasonic) caps and they'll probably run. I agree with changing all the electrolytics as there are only a couple of them. Even though the value may check out ok , there could be other problems with them such as the ESR value. I would guess the .068K would be a .068 UF at 250 volts. They seldom go bag. If only a few of the 47 uf you might as well change them while you are at it. While you could have other problems, the heating up seems to indicate the classic bad capacitors in the power supply. |
| hrhofmann@att.net: May 06 01:26PM -0700 I would first put the caps back in the circuit and see if it still behaves the same way. Your unsoldering and re-soldering may have fixed things due to a cold solder joint or other possible connection problems. |
| "pfjw@aol.com" <pfjw@aol.com>: May 06 03:07PM -0700 Mpfff.... Some basics on electrolytic caps: a) an electrolytic cap, unless otherwise marked can test +100%/-20% for value and still be in spec. And unless you have the ability to test them at full operating voltage, the information from a typical DVM is incomplete. b) an ESR meter is your friend. As noted elsewhere, testing is best done out of circuit. c) switching power supplies are very hard on caps. Replace them anyway, but also as noted, look for other heat sensitive failures also! Peter Wieck Melrose Park, PA |
| Jeff Liebermann <jeffl@cruzio.com>: May 06 04:46PM -0700 >two the power supply starts working. I was told by someone here or on >the basics group that there is probably a bad electrolytic capacitor >causing the problem. (...) Those are the classic symptoms of a defective electrolytic capacitor. You can't test an electrolytic with just a capacitance meter. you need an ESR (equivalent series resistance) meter. Often, I see them with the right capacitance, but with a high ESR. It's a common problem: <http://802.11junk.com/jeffl/pics/repair/slides/bad-caps.html> Notice how some of them are bulging at the top or bottom. As others have mentioned, it probably best to do an pre-emptive replacement than to try an save a few pennies seperating the good from the bad caps. In general, if one electrolytic is bad, they're all bad. After some provocation by Phil Allison, I ran a temperature test on various electrolytic capacitors: <http://802.11junk.com/jeffl/Electrolytic-cap-test/> Simple setup: <http://802.11junk.com/jeffl/Electrolytic-cap-test/test-setup.jpg> Test caps: <http://802.11junk.com/jeffl/Electrolytic-cap-test/caps.jpg> Spreadsheet showing results of temp test: <http://802.11junk.com/jeffl/Electrolytic-cap-test/cap-esr-test.xls> Notice how the ESR improves (goes down) with increasing temperature. That's why your power supply screws up at room temperature, but works when it's warmed up. There are a number of different ESR meters available. If you plan on doing such repairs in the future, you really should buy one. If you're not sure which one is suitable, I don't have any experience with this one, but it sure is cheap: <http://www.ebay.com/itm/131645169017> -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| jurb6006@gmail.com: May 06 05:30PM -0700 >" If you see any bulged caps, change them. " Note that does NOT apply to the big huge ones. Like the 470/200 main raw B+ filter for example, or those 10,000 at 80 volts in an amplifier. When it has that plastic sheath over it, the bulging top does NOT indicate it is bad. A guy I used to work with was told that and changed a like 470/200 and that did not fix the set, of course because it was not bad and he was not a real tech, he just did what he was told. Well days later I get to work on it because nobody else could fix it. The cap was in a bag with the screws and replaced parts. The cap was still charged ! That doesn't mean it could not have high ESR, but it was definitely not the cause of the problem. There are people who like to change ALL the caps in old hifi amps, I think they're wrong. While I will agree with changing the corresponding cap in the other channel when you find a bad one, or even weak one (significant ESR compared to Xc) it does not good to just change them all arbitrarily. It depends on where they are in the circuit, if used for bypass, what kind of current drain ? If used for coupling, what impedences ? It matters. |
| Ralph Mowery <rmowery28146@earthlink.net>: May 06 11:18PM -0400 In article <u1aqib12s73m6c57gjicuk5rkqk18d78cl@4ax.com>, jeffl@cruzio.com says... > you're not sure which one is suitable, I don't have any experience > with this one, but it sure is cheap: > <http://www.ebay.com/itm/131645169017> For a few dollars more you can get them already put together. I bought a similar one a few years back. Not sure how well it does the ESR but usually does a good job of testing many components. |
| Micky <NONONObobbyburns1111@gmail.com>: May 06 04:46PM -0400 Leaving small devices on constantly. I have some wireless speakers which use a wireless transmitter that is plugged into the sound output of the computer. I only actually listen to the wireless sound in other rooms 2 or 3 times a week for an hour or two** I'm not concerned about the electricity being use, but about wearing out the transmitter (about 4x4x1 inch) because I've been leaving it on all the time. If I remembered, it would be easy enough to turn it off because it's wall wart is plugged into "Master Power Plus" a flat box that sits under the monitor with 4 switches for whatever I plug into them (and a master switch). I use one for the transmitter, one for the local speakers, and I have used one for the monitor. So, does leaving the xmitter on all the time, year after year, make it likely to wear out sooner than turning it on 2 or 3 tiems a week for an hour or two, or more each time since I'll probably go out after lunch and won't want to go upstairs to turn the xmitter off again? P.S. I've been looking to buy another xmitter. I did buy another set of speakers but the ebay/CraigsList seller kept the xmitter back to test speakers as he got them. I have one spare that seemed to stop working years ago, but for some reason I wasn't convinced or I thought it was some perimeter problem I could fix. Thanks for any help you can give. **But it's very good to have because I can eat my dinner or take a bath or even work on the lawn mower outside etc. whenever I want without having to stay in the office near the computer to listen to a favorite program. RadioMaximus (free) has made it even easier to listen to a variety of webradio. |
| "pfjw@aol.com" <pfjw@aol.com>: May 06 03:14PM -0700 Most well made electronics actually benefit from being under power at all times. Exceptions would be surges, brown outs and lightening strikes. Three are always inrush surges, thermal issues and other faults relating to start-up and shutdown that are not good. I kept a Ramsey FM100B (1-watt version) when I worked overseas that now has been in operation 24/7 these last 11 years without a single glitch. Peter Wieck Melrose Park, PA |
| Micky <NONONObobbyburns1111@gmail.com>: May 06 06:56PM -0400 On Fri, 6 May 2016 15:14:12 -0700 (PDT), "pfjw@aol.com" <pfjw@aol.com> wrote: >Most well made electronics actually benefit from being under power at all times. Exceptions would be surges, brown outs and lightening strikes. Eventually I'll get all this conneced to a surge supressor, but in 33 years here, the numeric panel for the burglar alarm went up in smoke for some reason, but no other possible surge problems > Three are always inrush surges, thermal issues and other faults relating to start-up and shutdown that are not good. Okay >I kept a Ramsey FM100B (1-watt version) when I worked overseas that now has been in operation 24/7 these last 11 years without a single glitch. Now that you mention it, I have two tv signal amplifiers that have been plugged in for 32 and 30 years, except during 3 power failures and ~30 momentary interruptions and they still work fine. I'll leave it on. Thanks. |
| jurb6006@gmail.com: May 06 04:37PM -0700 Yup, things like that, don't worry about it. In fact some people leave their big power amps on all the time, and believe it or not they actually act as surge protectors in a way. When a surge id only a few milliseconds those big 10,000 uF caps do not charge all that much and they flatten it. I also never reboot my computers unless it is required for an anti-virus update. I also do not allow anything but the AV to update, at all. I works now so I do not want it fixed. When you first turn equipment on, that surge current can be like 100 times normal draw. If a CRT TV with an automatic degausser it can be way higher than that. In fact now some equipment has a surge limiting resistor that is shunted by a relay (for efficiency) after so long. Or there is Sony's plan using a zero crossing detector so the relay kicks in right when the AC is at zero. Little transmitters like that are not that critical. Turn off TV sets, class A amps and anything with tubes. Other than that leave it all on. |
| Jeff Liebermann <jeffl@cruzio.com>: May 06 04:56PM -0700 On Fri, 06 May 2016 16:46:05 -0400, Micky >likely to wear out sooner than turning it on 2 or 3 tiems a week for >an hour or two, or more each time since I'll probably go out after >lunch and won't want to go upstairs to turn the xmitter off again? No. Leaving it on will last longer than turning it on and off. Electronics does not like to be power cycled. Power electronics is worse because it doesn't like to be thermal cycled. I had a good example of longevity. I had an SCO ODT 486DX2/66 server running in my office 24x7 for about 15 years. I did manage to destroy a few CPU and power supply fans (if it moves, it breaks), but most everything else just ran and ran. The ancient Conner Peripherals CP1060S 1GB drive just kept going. I was waiting for it to die so I had an excuse to replace it, but it just kept going. I finally scrapped it about 6 months ago for parts that I needed to fix an ancient Omniturn machining center controller. Meanwhile, other machines, there were turned on and off as needed, would blow something up after about 5-7 years. The only exception I can think of are bulging electrolytic capacitors. They're killed by ripple current and over temperature, which is largely a function of operating time. So, if your xmitter is full of junk electrolytics, you might have more problems with continuous operation. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| jurb6006@gmail.com: May 06 05:17PM -0700 >largely a function of operating time. So, if your xmitter is full of >junk electrolytics, you might have more problems with continuous >operation. " With the shitylytics of today I think you'll have that anyway. They go bad without even being used. The old ones could be reformed, but not the new ones. In fact sometimes they leak right into the parts drawer. |
| Micky <NONONObobbyburns1111@gmail.com>: May 06 04:34PM -0400 >Sounds internal - AGC and compression in the voice handling - either >something detecting false levels on the mic, or a failing to return to >the Rx from Tx states ~flakey mike, There are Rx and Tx states in a wired phone?? |
| "pfjw@aol.com" <pfjw@aol.com>: May 06 02:59PM -0700 Some cheap phone on a chip wired phones use a single chip to do double duty. But such a problem as you describe seems unlikely even with that eventuality. And even so, that would mean a bad phone due for landfill. Peter Wieck Melrose Park, PA |
| Micky <NONONObobbyburns1111@gmail.com>: May 06 06:52PM -0400 On Fri, 6 May 2016 14:59:27 -0700 (PDT), "pfjw@aol.com" <pfjw@aol.com> wrote: >Some cheap phone on a chip wired phones use a single chip to do double duty. But such a problem as you describe seems unlikely even with that eventuality. And even so, that would mean a bad phone due for landfill. I'll also try unplugging the electricity next time, for a while. The wired part of the phone doesn't need it except to make the bell ring with a louder sound. But first I'll check out the cordless phone when the corded phone doesn't work right. |
| "Ian Field" <gangprobing.alien@ntlworld.com>: May 06 07:15PM +0100 <jurb6006@gmail.com> wrote in message news:901064af-a030-40c6-b8b2-b3fc441c0f61@googlegroups.com... > need to dissipate which raises the temperature. > Resistors do not lower in value unless abused. Even then, more than half > the time they open up. Most resistor types go high when overheated which limits the potential for damage. Glass cored resistors cause an increase in current and consequently the potential for damage. |
| You received this digest because you're subscribed to updates for this group. You can change your settings on the group membership page. To unsubscribe from this group and stop receiving emails from it send an email to sci.electronics.repair+unsubscribe@googlegroups.com. |
1 Response to Digest for sci.electronics.repair@googlegroups.com - 25 updates in 5 topics
YoBit allows you to claim FREE CRYPTO-COINS from over 100 distinct crypto-currencies, you complete a captcha one time and claim as much as coins you need from the available offers.
After you make about 20-30 claims, you complete the captcha and continue claiming.
You can press claim as many times as 30 times per one captcha.
The coins will stored in your account, and you can convert them to Bitcoins or USD.
Post a Comment