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Electrolytic ESR verus temperature test
I decided that it was time to run a test of what happens to the ESR of
an electrolytic capacitor over temperature. As always, there were a few too many surprises. http://802.11junk.com/jeffl/Electrolytic-cap-test/ The idea was to test electrolytics that might actually be used in a computer and which had a history of failing. I went to considerable trouble to make sure that the lead and contact resistance did not contribute any errors. The wires were silver plated and everything possible was soldered. In order to "zero out" the lead resistance, I crossed the capacitor leads and used pliers to short them. After some testing at room temperature, I found it to be highly repeatable. Test setup: http://802.11junk.com/jeffl/Electrolytic-cap-test/test-setup.jpg Each run took about 30 minutes. I ran temp tests on 4 different caps. Cap A = 1800 uf 6.3VDC. New. 105C. Purchased on eBay. Cap B = 2200 uf 10VDC. 105C. Removed from Dell with bulging top. Cap C = 1000 uf 6.3VDC. New. 105C. Unknown origin. Cap D = 0.22uf 50VDC. New. 85C. Unknown origin. http://802.11junk.com/jeffl/Electrolytic-cap-test/caps.jpg Spreadsheet with test results and graphs: http://802.11junk.com/jeffl/Electrolytic-cap-test/cap-esr-test.xls Cap A provided the initial surprise. The ESR was so low that the ESR meter reading was a constant 0.03 ohms above 40C. http://802.11junk.com/jeffl/Electrolytic-cap-test/Cap-A.jpg I would guess(tm) that this is a problem with the meter except that the meter reads my nichrome test wire, with less then 0.03 ohms quite nicely. Cap B is a known defective capacitor with a bulging top that had not quite blown open yet (i.e. no leaks). The starting ESR is well above normal. http://802.11junk.com/jeffl/Electrolytic-cap-test/Cap-B.jpg This produced almost a 10:1 decrease in ESR as Phil Allison predicted. Cap C was my attempt to find a cap that would give reasonable ESR values that would not produce the same lower limit problem as Cap A. http://802.11junk.com/jeffl/Electrolytic-cap-test/Cap-C.jpg It was better, but also hit bottom at 0.03 ohm. It's difficult to tell from the curve, but extrapolating from the starting values, it might have produced a 10:1 decrease in ESR if the meter had cooperated. Cap D was another attempt to get reasonable ESR values and which produced another surprise: http://802.11junk.com/jeffl/Electrolytic-cap-test/Cap-D.jpg Since the ESR was well above the previous attempts, I would have expected another 10:1 decrease in ESR. Instead, it only decreased about 1.5:1. This suggests that higher voltage electrolytics have a more constant ESR, but more testing will be needed to verify that guess. So, Phil is mostly correct. ESR does drop 10:1 in some electrolytic capacitors. Since power dissipation is directly proportional to the ESR (assuming a constant ripple current), a typical motherboard electrolytic capacitor will internally dissipate about 1/10th the power at maximum temperature as it would at room temperature. This explains an odd phenomenon that I've seen on computers with bulging caps on the motherboard. They'll sometimes run just fine when hot, but refuse to turn on function if allowed to cool. Also, I haven't seen any of this in the capacitor lifetime calculations. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Electrolytic ESR verus temperature test
"Jeff Liebermann" wrote in message ... I decided that it was time to run a test of what happens to the ESR of an electrolytic capacitor over temperature. As always, there were a few too many surprises. http://802.11junk.com/jeffl/Electrolytic-cap-test/ The idea was to test electrolytics that might actually be used in a computer and which had a history of failing. I went to considerable trouble to make sure that the lead and contact resistance did not contribute any errors. The wires were silver plated and everything possible was soldered. In order to "zero out" the lead resistance, I crossed the capacitor leads and used pliers to short them. After some testing at room temperature, I found it to be highly repeatable. Test setup: http://802.11junk.com/jeffl/Electrolytic-cap-test/test-setup.jpg Each run took about 30 minutes. I ran temp tests on 4 different caps. Cap A = 1800 uf 6.3VDC. New. 105C. Purchased on eBay. Cap B = 2200 uf 10VDC. 105C. Removed from Dell with bulging top. Cap C = 1000 uf 6.3VDC. New. 105C. Unknown origin. Cap D = 0.22uf 50VDC. New. 85C. Unknown origin. http://802.11junk.com/jeffl/Electrolytic-cap-test/caps.jpg Spreadsheet with test results and graphs: http://802.11junk.com/jeffl/Electrolytic-cap-test/cap-esr-test.xls Cap A provided the initial surprise. The ESR was so low that the ESR meter reading was a constant 0.03 ohms above 40C. http://802.11junk.com/jeffl/Electrolytic-cap-test/Cap-A.jpg I would guess(tm) that this is a problem with the meter except that the meter reads my nichrome test wire, with less then 0.03 ohms quite nicely. Cap B is a known defective capacitor with a bulging top that had not quite blown open yet (i.e. no leaks). The starting ESR is well above normal. http://802.11junk.com/jeffl/Electrolytic-cap-test/Cap-B.jpg This produced almost a 10:1 decrease in ESR as Phil Allison predicted. Cap C was my attempt to find a cap that would give reasonable ESR values that would not produce the same lower limit problem as Cap A. http://802.11junk.com/jeffl/Electrolytic-cap-test/Cap-C.jpg It was better, but also hit bottom at 0.03 ohm. It's difficult to tell from the curve, but extrapolating from the starting values, it might have produced a 10:1 decrease in ESR if the meter had cooperated. Cap D was another attempt to get reasonable ESR values and which produced another surprise: http://802.11junk.com/jeffl/Electrolytic-cap-test/Cap-D.jpg Since the ESR was well above the previous attempts, I would have expected another 10:1 decrease in ESR. Instead, it only decreased about 1.5:1. This suggests that higher voltage electrolytics have a more constant ESR, but more testing will be needed to verify that guess. So, Phil is mostly correct. ESR does drop 10:1 in some electrolytic capacitors. Since power dissipation is directly proportional to the ESR (assuming a constant ripple current), a typical motherboard electrolytic capacitor will internally dissipate about 1/10th the power at maximum temperature as it would at room temperature. This explains an odd phenomenon that I've seen on computers with bulging caps on the motherboard. They'll sometimes run just fine when hot, but refuse to turn on function if allowed to cool. Also, I haven't seen any of this in the capacitor lifetime calculations. -- Jeff Liebermann I haven't had a chance yet to fully examine your results links, but I thought that I would just wade in to say that your last observation is very common with other equipment such as TV sets, and indeed switchmode power supplies in general. I see examples of this most every week where a piece of equipment has a power supply that only goes to a standby mode when the owner of the equipment switches it "off". Then they go on holiday, and switch it off for real, and when they come back and try to start it up again - nothing. And the cause is always bad electros that were fine when they were kept warm but went too high on their ESR to fulfill their circuit function, when thy fully cooled. Arfa |
Electrolytic ESR verus temperature test
"Arfa Daily" I haven't had a chance yet to fully examine your results links, but I thought that I would just wade in to say that your last observation is very common with other equipment such as TV sets, and indeed switchmode power supplies in general. I see examples of this most every week where a piece of equipment has a power supply that only goes to a standby mode when the owner of the equipment switches it "off". Then they go on holiday, and switch it off for real, and when they come back and try to start it up again - nothing. And the cause is always bad electros that were fine when they were kept warm but went too high on their ESR to fulfill their circuit function, when thy fully cooled. ** Would you be thinking of low value electros ( like 1 or 2.2 uF at 400V ) that are used to " kick start" SMPS ? Notoriously short lived, their failure goes un-noticed until the unit is left unplugged for a time. Plagued many TVs and most VCRs right through the 80 and early 90s. The same dopey problem is causing havoc with LED tube lighting right now - cos the Chinese have yet to discover it. Parallels the Yellow Glue disaster nicely. .... Phil |
Electrolytic ESR verus temperature test
"Phil Allison" wrote in message ... "Arfa Daily" I haven't had a chance yet to fully examine your results links, but I thought that I would just wade in to say that your last observation is very common with other equipment such as TV sets, and indeed switchmode power supplies in general. I see examples of this most every week where a piece of equipment has a power supply that only goes to a standby mode when the owner of the equipment switches it "off". Then they go on holiday, and switch it off for real, and when they come back and try to start it up again - nothing. And the cause is always bad electros that were fine when they were kept warm but went too high on their ESR to fulfill their circuit function, when they fully cooled. ** Would you be thinking of low value electros ( like 1 or 2.2 uF at 400V ) that are used to " kick start" SMPS ? Notoriously short lived, their failure goes un-noticed until the unit is left unplugged for a time. Plagued many TVs and most VCRs right through the 80 and early 90s. The same dopey problem is causing havoc with LED tube lighting right ow - cos the Chinese have yet to discover it. Parallels the Yellow Glue disaster nicely. ... Phil I was thinking more the typical 47uF 35v ones that hang across the supply pin to the controller IC, and effectively reduce the otherwise high impedance of the startup supply for a brief time, in order that it can supply enough current to get the chip started so that the low impedance maintenance supply from the secondary side can get going and take over. I see so many caps in that position that are high ESR and stop the supply from starting, that I order them fifty at a time. And one particular supply that I repair lots of for a company, has the Yellow Glue syndrome as well, and where is it ? Yep, all around the base of that same 47uF cap ... Yes, also used to see a lot of the high voltage 1uF's o/c, but not so much these days. I was also thinking of secondary side 1000 and 2200uF caps. Again, when kept warm, they often work ok, despite showing signs of bulging, but go very high ESR when cold. In TV sets, this often leads to them taking longer and longer to start, until finally, they won't start at all. This can be because of excess ripple on the 5 volt rail, upsetting the system control micro, or excess ripple on the 12 or 24 volt rails, upsetting things like the backlight inverter, or rails of completely the wrong voltage if the whole supply is regulated from the bad rail. I have seen 5 volt rails increase to 10 or more volts because of this, with LSIs elsewhere in the equipment being destroyed as a result ... Arfa |
Electrolytic ESR verus temperature test
On Sun, 7 Jul 2013 10:44:57 +0100, "Arfa Daily"
wrote: "Jeff Liebermann" wrote in message .. . This explains an odd phenomenon that I've seen on computers with bulging caps on the motherboard. They'll sometimes run just fine when hot, but refuse to turn on function if allowed to cool. I haven't had a chance yet to fully examine your results links, but I thought that I would just wade in to say that your last observation is very common with other equipment such as TV sets, and indeed switchmode power supplies in general. I see examples of this most every week where a piece of equipment has a power supply that only goes to a standby mode when the owner of the equipment switches it "off". Then they go on holiday, and switch it off for real, and when they come back and try to start it up again - nothing. And the cause is always bad electros that were fine when they were kept warm but went too high on their ESR to fulfill their circuit function, when thy fully cooled. Arfa It's all too common with servers and machines that are powered on all the time. Last week, I had to deal with an office computer like that. Powered on 24x7 and nothing wrong. However, it was full of dust, so I thought it could use a cleaning. I turned it off, blew out the dust (outside), and it refused to turn on. When I tore apart the ATX power supply, there were three obvious bulging caps. While I had the cover off, I decided to run a little test. I gave the PCB a blast from a heat gun to get it up to temperature and found that it will turn on. I have several cheap ATX testers, one of which has a built in load for the +5V and +12V lines. I connected an oscilloscope to these lines to see if there was any ripple. Both were fairly clean (I forgot the numbers) but as the power supply cooled down, the +5V noise started ominously increasing. The PG (power good) light was oddly thrashing. When I turned it off, it didn't want to turn on again. It was too old and ugly to repair, so I just installed a replacement. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Electrolytic ESR verus temperature test
On 7/7/2013 8:14 AM, Jeff Liebermann wrote:
On Sun, 7 Jul 2013 10:44:57 +0100, "Arfa Daily" wrote: "Jeff wrote in message ... This explains an odd phenomenon that I've seen on computers with bulging caps on the motherboard. They'll sometimes run just fine when hot, but refuse to turn on function if allowed to cool. I haven't had a chance yet to fully examine your results links, but I thought that I would just wade in to say that your last observation is very common with other equipment such as TV sets, and indeed switchmode power supplies in general. I see examples of this most every week where a piece of equipment has a power supply that only goes to a standby mode when the owner of the equipment switches it "off". Then they go on holiday, and switch it off for real, and when they come back and try to start it up again - nothing. And the cause is always bad electros that were fine when they were kept warm but went too high on their ESR to fulfill their circuit function, when thy fully cooled. Arfa It's all too common with servers and machines that are powered on all the time. Last week, I had to deal with an office computer like that. Powered on 24x7 and nothing wrong. However, it was full of dust, so I thought it could use a cleaning. I turned it off, blew out the dust (outside), and it refused to turn on. When I tore apart the ATX power supply, there were three obvious bulging caps. While I had the cover off, I decided to run a little test. I gave the PCB a blast from a heat gun to get it up to temperature and found that it will turn on. I have several cheap ATX testers, one of which has a built in load for the +5V and +12V lines. I connected an oscilloscope to these lines to see if there was any ripple. Both were fairly clean (I forgot the numbers) but as the power supply cooled down, the +5V noise started ominously increasing. The PG (power good) light was oddly thrashing. When I turned it off, it didn't want to turn on again. It was too old and ugly to repair, so I just installed a replacement. It's not just the power supplies that have that problem. We have a selective soldering machine, CNC controlled, using a pc with a no longer available video card. Ran fine for several years when the machine was on 24 hours per day. Then when work slowed, and the machine was off for several days, the video would act up, then settle down and work fine. Time to run properly took longer and longer, till one day, it wouldn't display at all. Factory had no replacement boards available, and in fact had quit using them because of problems. We replaced all the electrolytic caps with ones close to the original value. Had bags full! And the board has performed correctly ever since. Paul |
Electrolytic ESR verus temperature test
Arfa Daily wrote: I haven't had a chance yet to fully examine your results links, but I thought that I would just wade in to say that your last observation is very common with other equipment such as TV sets, and indeed switchmode power supplies in general. I see examples of this most every week where a piece of equipment has a power supply that only goes to a standby mode when the owner of the equipment switches it "off". Then they go on holiday, and switch it off for real, and when they come back and try to start it up again - nothing. And the cause is always bad electros that were fine when they were kept warm but went too high on their ESR to fulfill their circuit function, when thy fully cooled. Has anyone tried one of these $18 ESR meters? http://www.ebay.com/itm/190859294488 |
Electrolytic ESR verus temperature test
"Cap D was another attempt to get reasonable ESR values and which
produced another surprise: http://802.11junk.com/jeffl/Electrolytic-cap-test/Cap-D.jpg Since the ESR was well above the previous attempts, I would have expected another 10:1 decrease in ESR. Instead, it only decreased about 1.5:1. This suggests that higher voltage electrolytics have a more constant ESR, but more testing will be needed to verify that guess. " It might not be so much of a surprise. Do you happen to know what frequency the ESR meter uses ? Thing is, if they choose the frequency too high there will be some error due to ESL in the larger cap values. Too low and the ESR of a 0.22uF will inherently read high because of the Xc component. In this case you might not be getting empirical data but rather a more "usable" figure for servicing as that is the intended application of most ESR meters. Granted, the higher ESR of a lower value such as a 0.22 might be well acceptable for use in real circuitry because of course they would not expect it to handle much ripple current. Well not so much current for the obvious reason. If a low value like that is ever used for filtering it is more likely a local cap near a linear regulator to stop oscillation. It would never be the main filtering on a power supply line unless it was extremely low current, and unless they wanted the source to rise and drop fast, a higher value cap would likely be chosen most of the time anyway, like a 1 uF or something, or anything they are already using a bunch of to get a better price. Actually, if you want to get persnickety about it (that is not a bad thing) you could run the test with a sine wave generator and a scope or voltmeter.. It's not difficult, and you could isolate the ESL component completely by using a set of frequencies that keep the Xc to a minimal value. And now, I might just have to do that myself because I would like to know how temperature affects ESL. I would bet it does, and depending on the frequency applied might throw off the ESR measurement as would Xc. You are talking from 1,800 down to 0.22, that is like a one to eight thousand ratio. There must be some effect but I am not going to figure it out right now, especially not knowing the frequency applied to the DUT. |
Electrolytic ESR verus temperature test
Incidentally, years ago I designed an ESR meter but was too lazy to actually build it. My scheme to get a wider range of accurate ESR values for different value caps was to apply a square wave to the DUT. I had two scales discriminated for high and low frequency and the square wave was positive going only so it could detect a short easily. I chose a low amplitude like a couple hundred millivolts to prevent the short/leakage detect from triggering if the polarity was wrong, or if there were semis in circuit that would conduct. Of course if Schottky rectifiers were used it might still false trigger, but then it was just a matter of the user reversing the leads.
I used a pretty low inpedance so that it would read fast, and made it so discharging wasn't necessary. My main concern was mass cap testing at the time as I knew plenty of techs that just check all the caps regardless of the symptom and where they were in the circuit. I don't do that. In fact I don't even replace all the "bad" ones either, as some are more critical than others. Some are very uncritical. The engineer might use a 100 uF where a 22 would work just fine, but they get a price break using the 100, on all 100s in each unit of course. Basically if there is no AC across the cap when it is working and it is not leaking electrolyte, it does not need to be changed. Hillbilly ? Fine, but market conditions have made me this way. The only thing that will stop me from ever pushing down the bottom line is recalls, or safety issues. |
Electrolytic ESR verus temperature test
"Arfa Daily" "Phil Allison" ** Would you be thinking of low value electros ( like 1 or 2.2 uF at 400V ) that are used to " kick start" SMPS ? I was thinking more the typical 47uF 35v ones that hang across the supply pin to the controller IC, ** Like the UC3842N ? see so many caps in that position that are high ESR and stop the supply from starting, that I order them fifty at a time. ** So you are doing warranty work on home studio powered speakers that run 24/7 ? And one particular supply that I repair lots of for a company, has the Yellow Glue syndrome as well, and where is it ? Yep, all around the base of that same 47uF cap ... ** The PSU board in the " Alesis M1 Active" - right ? Where the problem is not due to bad electros at all. But a 2W resistor that almost touches the cap and heats it to a high temp for 8,760 hours per year. Wot a piece of garbage. .... Phil |
Electrolytic ESR verus temperature test
Do you happen to know what frequency the ESR meter uses ? Thing is, if they choose the frequency too high there will be some error due to ESL in the larger cap values. ** Not true for Bob's design. Even large can electros with bolts on top have ESL values of about 20nH = much the same value for nearly all electros. At 100kHz, this results in a reactance of 0.01 ohms = the resolution of Bob's ESR meter. Too low and the ESR of a 0.22uF will inherently read high because of the Xc component. ** Bobs meter is NOT suitable for low value caps ( under 1uF ) or any cap type except aluminium electros. In this case you might not be getting empirical data but rather a more "usable" figure for servicing as that is the intended application of most ESR meters. ** Most low value electros have high ESRs ( like 20 or 30 ohms) and this saves the day. Tantalums are an exception, but as they do not have an issue with rising ESR it is irrelevant to the purpose of Bob's meter. ..... Phil |
Electrolytic ESR verus temperature test
"Jeff Liebermann = Idiot "
It's not an issue, but let's see. I had about 30cm of #18 wire leads connected to the capacitor under test. ** You should used a twisted pair of leads, figure 8 twin lead or even co-ax, which form transmission lines at high frequencies and series L all but vanishes. The residual before zeroing is then less than 1ohm. My god you are a ****wit . .... Phil |
Electrolytic ESR verus temperature test
On Mon, 8 Jul 2013 13:59:06 +1000, "Phil Allison"
wrote: "Jeff Liebermann = Idiot " It's not an issue, but let's see. I had about 30cm of #18 wire leads connected to the capacitor under test. ** You should used a twisted pair of leads, figure 8 twin lead or even co-ax, which form transmission lines at high frequencies and series L all but vanishes. The residual before zeroing is then less than 1ohm. Good idea. So, I tried it. http://802.11junk.com/jeffl/Electrolytic-cap-test/coax.jpg I get between 0.3 and 0.6 ohms residual reading. The problem is that the BNC connectors are not the best DC connection possible. Wiggle the connectors and the reading changes. That's why I soldered almost everything on my insulated hookup wire version. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Electrolytic ESR verus temperature test
On Sun, 07 Jul 2013 19:01:54 -0700, Jeff Liebermann
wrote: It's not an issue, but let's see. I had about 30cm of #18 wire leads connected to the capacitor under test. http://www.consultrsr.com/resources/eis/induct5.htm That's about 0.43uH. At 100Khz, that's about 25 ohms. Ooops. That should be 0.38uH and 0.24 ohms. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Electrolytic ESR verus temperature test
I think to be properly persnickety you are going to have to change the vertical scale on those graphs from "ESR" to "impedance".
I have a bunch more to say on this but it is late and I am half drunk. Off work tomorrow... I wonder what kind of readings you might see out of things like motor start or run caps, or speaker crossover caps. In fact the run cap in my AC unit took a **** last year and I had to replace it, after that the summer electric usage went down. I wonder if I could go around selling cap jobs to homeowners and claim honestly that it will save them money in the next few seasons. It would also prevent unscrupulous assholes from selling them a whole new unit. At first I priced new condensing units and it is hard as hell to get them with R22 these days. And then there is some doubt about how well it would work with the original evaporator and cap tube or expansion valve, which might mean tearing the whole damn thing down. Cap is about twenty bucks, charge a hundred for the job, lasts five years and almost guaranteed to save them that in the next five seasons ? Now that would be some serious math. I am lazy when it coes to that. I would like easy ways do calculate Xc, Xl and do vector math. there is probably a way out ther eI just haven't found it. In fact I would be happy with a reactance/resonance table. Damn, with a computer it could be zoomable and just eliminate all this..... You know in the old BASIC days I had programs for that. Also for calculating new displacements of engines bored out, carberator requiremnets, all that cool ****. But I did it once and minded my syntax, and didn't have to do it again. Until I fell behind on programming. Well I was never really ahead, I just made it do a few things I wanted it to do because I used to design things here abnd there and build them. I got a bone to pick with time, I lack my ambition, something took it ! Call the electron police..... |
Electrolytic ESR verus temperature test
"Phil Allison" wrote in message ... "Arfa Daily" "Phil Allison" ** Would you be thinking of low value electros ( like 1 or 2.2 uF at 400V ) that are used to " kick start" SMPS ? I was thinking more the typical 47uF 35v ones that hang across the supply pin to the controller IC, ** Like the UC3842N ? Yes, that series of IC. There are quite a few UC38xx chips about see so many caps in that position that are high ESR and stop the supply from starting, that I order them fifty at a time. ** So you are doing warranty work on home studio powered speakers that run 24/7 ? I do work for several hifi shops, and see quite a few powered subs, some of which have switchers in them, and suffer from caps, but I also do a fair bit of work on other items that are powered 24/7 like DVD players / home cinema systems and set top boxes. And one particular supply that I repair lots of for a company, has the Yellow Glue syndrome as well, and where is it ? Yep, all around the base of that same 47uF cap ... ** The PSU board in the " Alesis M1 Active" - right ? The actual one that I was thinking of is from a commercial hot drinks machine. The company that sends me them, has them rented out into workplaces and takeaways and educational establishments all over the country, so there's never any shortage of them for repair. It has a small vertical sub-pcb that has the switch mode controller and driver on it. The 47uF is laid over on its side, and then fixed to the board with the dreaded yellow glue. The actual mix of faults is about 50 / 50. If the glue has started to go brown, chances are that's the primary problem, and the cap is actually ok, reading normally on the ESR meter. If the glue hasn't gone yellow, then most times, the cap reads bad. But to be honest, whether it's actually cap or glue, I always just go ahead and remove the cap, clean up the board, and then fit a new cap. They are so cheap, it's not worth doing anything else and risking it bouncing a couple of months later. Where the problem is not due to bad electros at all. But a 2W resistor that almost touches the cap and heats it to a high temp for 8,760 hours per year. Yes, I've never understood this. It seems to be almost a 'design rule' that any electrolytic should be mounted as close to a heat source on the PCB as possible ... Anyone in the repair business knows that this is going to lead to problems after not too long a life. If I suspect a cap problem on any piece of circuitry, the first ones that I check are those near to big resistors and heatsinks. How come this has never managed to get back to the designers, and the supervisors who approve the designs ? Seems to be common across all manufacturers. Wot a piece of garbage. Many are Arfa ... Phil |
Electrolytic ESR verus temperature test
"Michael A. Terrell" wrote in message m... Arfa Daily wrote: I haven't had a chance yet to fully examine your results links, but I thought that I would just wade in to say that your last observation is very common with other equipment such as TV sets, and indeed switchmode power supplies in general. I see examples of this most every week where a piece of equipment has a power supply that only goes to a standby mode when the owner of the equipment switches it "off". Then they go on holiday, and switch it off for real, and when they come back and try to start it up again - nothing. And the cause is always bad electros that were fine when they were kept warm but went too high on their ESR to fulfill their circuit function, when thy fully cooled. Has anyone tried one of these $18 ESR meters? http://www.ebay.com/itm/190859294488 I recently bought one of the similar ones that has component testing on it as well as ESR http://www.ebay.co.uk/itm/1810723297... 4.m1439.l2648 and I have to say that it works very well. ESR function agrees nicely with my Bob Parker Arfa |
Electrolytic ESR verus temperature test
Yes, I've never understood this. It seems to be almost a 'design rule' that any electrolytic should be mounted as close to a heat source on the PCB as possible ... Anyone in the repair business knows that this is going to lead to problems after not too long a life. If I suspect a cap problem on any piece of circuitry, the first ones that I check are those near to big resistors and heatsinks. How come this has never managed to get back to the designers, and the supervisors who approve the designs ? Seems to be common across all manufacturers. Wot a piece of garbage. Many are Arfa ... Phil Perfect example, 10 minutes ago. JVC XV-THS8 home cinema unit. Totally dead. First component I went for was the 47uF startup supply buffer cap for the 5 legged TO-220 one chip SMPS solution. Why did I go straight for that cap ? Because it was located right next to the chip's heatsink. So close it was almost touching. It went 40 ohms on my Bob Parker, and a new one sorted the problem immediately. As a matter of particular interest to Michael T, I hung the faulty one across the little Chinese component tester that I mentioned elsewhere in the thread. That made it 42 ohms, so pretty good agreement with Bob's meter. But what was also of note was the fact that the tester showed it to have a value of 44.6 uF, so not far from its nominal 47uF, even though it was clearly well out of spec on its ESR. This underlines what we have discussed on here before in that you cannot determine the condition of an electrolytic by measuring its capacitance alone. It has to have its ESR checked to get a meaningful result, and that is best, and most conveniently, done with a proper in-circuit ESR meter, that's designed for the job. Arfa |
Electrolytic ESR verus temperature test
Arfa Daily wrote: "Michael A. Terrell" wrote in message m... Arfa Daily wrote: I haven't had a chance yet to fully examine your results links, but I thought that I would just wade in to say that your last observation is very common with other equipment such as TV sets, and indeed switchmode power supplies in general. I see examples of this most every week where a piece of equipment has a power supply that only goes to a standby mode when the owner of the equipment switches it "off". Then they go on holiday, and switch it off for real, and when they come back and try to start it up again - nothing. And the cause is always bad electros that were fine when they were kept warm but went too high on their ESR to fulfill their circuit function, when thy fully cooled. Has anyone tried one of these $18 ESR meters? http://www.ebay.com/itm/190859294488 I recently bought one of the similar ones that has component testing on it as well as ESR http://www.ebay.co.uk/itm/1810723297... 4.m1439.l2648 Don't you love that they never bother to mount the LCDs in these designs? and I have to say that it works very well. ESR function agrees nicely with my Bob Parker The original, or the newer one? I have the original, bought as a kit. |
Electrolytic ESR verus temperature test
On 7/8/2013 4:36 PM, Arfa Daily wrote:
"Phil Allison" wrote in message ... "Arfa Daily" "Phil Allison" ** Would you be thinking of low value electros ( like 1 or 2.2 uF at 400V ) that are used to " kick start" SMPS ? I was thinking more the typical 47uF 35v ones that hang across the supply pin to the controller IC, ** Like the UC3842N ? Yes, that series of IC. There are quite a few UC38xx chips about see so many caps in that position that are high ESR and stop the supply from starting, that I order them fifty at a time. ** So you are doing warranty work on home studio powered speakers that run 24/7 ? I do work for several hifi shops, and see quite a few powered subs, some of which have switchers in them, and suffer from caps, but I also do a fair bit of work on other items that are powered 24/7 like DVD players / home cinema systems and set top boxes. And one particular supply that I repair lots of for a company, has the Yellow Glue syndrome as well, and where is it ? Yep, all around the base of that same 47uF cap ... ** The PSU board in the " Alesis M1 Active" - right ? The actual one that I was thinking of is from a commercial hot drinks machine. The company that sends me them, has them rented out into workplaces and takeaways and educational establishments all over the country, so there's never any shortage of them for repair. It has a small vertical sub-pcb that has the switch mode controller and driver on it. The 47uF is laid over on its side, and then fixed to the board with the dreaded yellow glue. The actual mix of faults is about 50 / 50. If the glue has started to go brown, chances are that's the primary problem, and the cap is actually ok, reading normally on the ESR meter. If the glue hasn't gone yellow, then most times, the cap reads bad. But to be honest, whether it's actually cap or glue, I always just go ahead and remove the cap, clean up the board, and then fit a new cap. They are so cheap, it's not worth doing anything else and risking it bouncing a couple of months later. Where the problem is not due to bad electros at all. But a 2W resistor that almost touches the cap and heats it to a high temp for 8,760 hours per year. Yes, I've never understood this. It seems to be almost a 'design rule' that any electrolytic should be mounted as close to a heat source on the PCB as possible ... Anyone in the repair business knows that this is going to lead to problems after not too long a life. If I suspect a cap problem on any piece of circuitry, the first ones that I check are those near to big resistors and heatsinks. How come this has never managed to get back to the designers, and the supervisors who approve the designs ? Probably it is intentionally. Seems to be common across all manufacturers. First manufacturers learned how to make almost perfect stuff. But then they sell less. Remember the TV sets working for 20 years or more. Now they cripple the equipment. Most flat screen TV sets do 5 to 8 year. |
Electrolytic ESR verus temperature test
"tinkerbell" First manufacturers learned how to make almost perfect stuff. ** Huh ? On what planet was this ? Remember the TV sets working for 20 years or more. ** No, that was never the case. Now they cripple the equipment. Most flat screen TV sets do 5 to 8 year. ** And cost less to own per year in real terms that any TV set previously available. **** off, fool. ..... Phil |
Electrolytic ESR verus temperature test
On Mon, 8 Jul 2013, tuinkabouter wrote:
First manufacturers learned how to make almost perfect stuff. But then they sell less. Remember the TV sets working for 20 years or more. Are you talking about tube tv sets? A significant issue is that in the age of tubes, electrolytic capacitors were relatively uncommon. ONe or two in the power supply filter, then to bypass the audio output amplifier cathode, maybe a few more. Tubes were high impedance, so the capacitor values matched. If you don't need high value capacitors, then you don't need electrolytics. Most tube equipment, besides not using many electrolytics, used relatively small value electrolytics. Then the solid state age came along. Low impedance devices, so high value capacitors became pretty common. Look at a transistor radio from the sixties and wham, a whole lot of electrolytics, because they were the only way to get the needed higher value capacitors. And it got worse, since a transistor radio was pretty simple, but once ICs and specifically digital ICs came along, the need for high value capacitors kept going up. The filter capacitors in many a tube equipment was 40uF or so, really quite small in value. IN the solid state age, 40uF was a low value, hundreds of uF became common. Suddenly electrolytic capacitors were everywhere, so the chance of failure went up. IN the digital age, the capacitors weren't even seeing low 60Hz AC, like the old tube radios saw, they were dealing with much higher frequencies. In 1975, all the home computers coming on the market used massive power supplies, big transformers and coke can size electrolytics. But those were heavy and used up space, so when the Apple II came along, it used a switching supply, something that was relatively unknown in hobby circles, or consumer electronics. That really put the electrolytics to the test, putting them against high frequencies, and putting them against high temperature devices. It was a whole different world from the days of tubes. Virtually nobody talked about ESR in the days of tubes. But sometime into the digital age, suddenly ESR became a factor for a whole lot more people, suddenly you could buy ESR meters. That's the transition, the number of electrolytics in any device went up, their values went up, and the frequencies they dealt with went up. And so it's natural that they'd start failing faster than in the days of tubes, and maybe more important, the failure wnas't as obvious as in a tube radio (where you'd hear the hum in the spaeker when the capacitors went bad) and since there were now so many electrolytics, it wasn't an easy matter of "just replace the handful of electrolytics". You needed to find out which was bad, and thus the rise of ESR meters. Micahel |
Electrolytic ESR verus temperature test
Remember the TV sets working for 20 years or more.
** No, that was never the case. I've had a Sony and an NAD that lasted 20 years. The Sony WEGA in my bedroom is almost 13 years old, and going strong. |
Electrolytic ESR verus temperature test
Michael Black wrote: Virtually nobody talked about ESR in the days of tubes. That's because it was called 'Power Factor'. |
Electrolytic ESR verus temperature test
On Mon, 8 Jul 2013 17:02:56 -0400, Michael Black wrote:
Nicely written description. Permit me to add a few comments. The filter capacitors in many a tube equipment was 40uF or so, really quite small in value. IN the solid state age, 40uF was a low value, hundreds of uF became common. Well, let's do the math. The energy stored in a capacitor is: E = 1/2*C*V^2 which means that for the same energy storage, if you cut the operating voltage in half, you have to increase the capacitance by a factor of four (assuming a load with the same number of watts). So, when we go from 40 uf at 300 VDC B+, to a switcher running at 5 VDC, the capacitor has to be: 40 * (300/5)^0.5 = 2400 uf for the same energy storage. so when the Apple II came along, it used a switching supply, something that was relatively unknown in hobby circles, or consumer electronics. That really put the electrolytics to the test, putting them against high frequencies, and putting them against high temperature devices. Steve Jobs also didn't want to have a cooling fan in the Apple ][ making thermal management was a big problem. More on the Apple ][ power supply: http://www.righto.com/2012/02/apple-didnt-revolutionize-power.html Virtually nobody talked about ESR in the days of tubes. True. We dealt with capacitor "Q" or its inverse, which is dissipation factor: http://en.wikipedia.org/wiki/Dissipation_factor Dissipation factor is more correct because it includes the phase angle between the resistive (ESR) and reactive parts. However, only the resistive (ESR) actually produces heat, so it's understandable that the reactive part should be ignored. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Electrolytic ESR verus temperature test
On Mon, 8 Jul 2013 01:21:37 -0700 (PDT), wrote:
I think to be properly persnickety you are going to have to change the vertical scale on those graphs from "ESR" to "impedance". Nope. The correct measurement would be dissipation factor: http://en.wikipedia.org/wiki/Dissipation_factor which is a conglomeration of the resitive part of the impedance (ESR), and the capacitive reactance part (1/2PiFC). For this exercise, I'm only interested in the part that actually produces heat, which is ESR. The reactive parts generates no heat and can therefore be ignored. I have a bunch more to say on this but it is late and I am half drunk. Off work tomorrow... Alcohol should best be used for removing solder flux residue. I wonder what kind of readings you might see out of things like motor start or run caps, or speaker crossover caps. Dunno. I don't work on speakers and the motor caps are really obvious when they need replacement. I am lazy when it coes to that. I would like easy ways do calculate Xc, Xl and do vector math. there is probably a way out ther eI just haven't found it. In fact I would be happy with a reactance/resonance table. Damn, with a computer it could be zoomable and just eliminate all this..... In the bad old daze, I used nomograms for all that. These days, I just Google for a suitable Javscript based online calculator. I also have reactance and resonance calcs programmed into my HP41CX and other HP programmable calculators. However, the online version is easer to read and use. Until I fell behind on programming. Well I was never really ahead, I don't have much trouble programming for myself and on my own projects. However, I don't like programming and am not very good at it. To avoid dissapointing friends and customers that want me to program, I plea ignorance. I got a bone to pick with time, I lack my ambition, something took it ! Call the electron police..... Sorry, but the electron police had its funding redirected by the government so that the NSA can built the ultimate telephone directory. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Electrolytic ESR verus temperature test
On Sun, 07 Jul 2013 00:52:47 -0700, Jeff Liebermann
wrote: The data is rather interesting, and somewhat revealing. It occurred to me to wonder what the actual leakage current, and capacitance was for similiar conditions in each case. peter |
Electrolytic ESR verus temperature test
|
Electrolytic ESR verus temperature test
On Tue, 09 Jul 2013 10:00:06 +1000, Peter wrote:
On Sun, 07 Jul 2013 00:52:47 -0700, Jeff Liebermann wrote: The data is rather interesting, and somewhat revealing. It occurred to me to wonder what the actual leakage current, and capacitance was for similiar conditions in each case. peter I was going to do that, just to see what happened. However, it was midnight and I had just enough time to write it up before I fell over. I need to measure the capacitance over temperature in order to remove the capacitive reactance from the ESR measurements on the small value cap (Cap-D). I don't consider leakage current to be significant at the voltages found in computer power supplies and motherboards, but testing might prove otherwise. Application Guide Aluminum Electrolytic Capacitors: http://electrochem.cwru.edu/encycl/m...4-appguide.pdf DC Leakage Current (DCL) DC Leakage Current is the DC current flowing through the capacitor with the rated voltage applied. The value of leakage current depends on the voltage applied, the charging period and capacitor temperature. DCL Method of measurement Measure leakage current at 25 °C with the rated voltage applied through a protective resistance of 1000 Ohm in series with the capacitor in the measuring circuit. Five minutes after the application of voltage, the leakage current is not to exceed the maximum value indicated in the specification. The 5 minutes delay is to reduce the effects of forming current and dielectric absorption. There are some typical graphs of leakage versus temperature and voltage on Pg 2.191. I guess the easy way to measure current is to just measure the voltage across the 1000 ohm resistor and compute the current. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Electrolytic ESR verus temperature test
"Michael A. Terrell" wrote in message m... Arfa Daily wrote: "Michael A. Terrell" wrote in message m... Arfa Daily wrote: I haven't had a chance yet to fully examine your results links, but I thought that I would just wade in to say that your last observation is very common with other equipment such as TV sets, and indeed switchmode power supplies in general. I see examples of this most every week where a piece of equipment has a power supply that only goes to a standby mode when the owner of the equipment switches it "off". Then they go on holiday, and switch it off for real, and when they come back and try to start it up again - nothing. And the cause is always bad electros that were fine when they were kept warm but went too high on their ESR to fulfill their circuit function, when thy fully cooled. Has anyone tried one of these $18 ESR meters? http://www.ebay.com/itm/190859294488 I recently bought one of the similar ones that has component testing on it as well as ESR http://www.ebay.co.uk/itm/1810723297... 4.m1439.l2648 Don't you love that they never bother to mount the LCDs in these designs? and I have to say that it works very well. ESR function agrees nicely with my Bob Parker The original, or the newer one? I have the original, bought as a kit. The original, also bought as a kit. Did you see the other post that I did today that detailed a comparison between the Bob P and the little Chinese job on a faulty cap that I had cause to replace ? Arfa |
Electrolytic ESR verus temperature test
"Jeff Liebermann is bad at math" The filter capacitors in many a tube equipment was 40uF or so, really quite small in value. IN the solid state age, 40uF was a low value, hundreds of uF became common. Well, let's do the math. The energy stored in a capacitor is: E = 1/2*C*V^2 which means that for the same energy storage, if you cut the operating voltage in half, you have to increase the capacitance by a factor of four (assuming a load with the same number of watts). So, when we go from 40 uf at 300 VDC B+, to a switcher running at 5 VDC, the capacitor has to be: 40 * (300/5)^0.5 = 2400 uf for the same energy storage. ** How about 40* (300/5)^2 = 144,000 uF But energy storage is simply NOT the issue. Electros used at the output of SMPSs are there to suppress ripple voltage down to a few mV at currents of many amps. So their impedance at frequencies between 20kHz and 100KHz must be as low as possible. Modern electros in the thousands of uF have very low, broad impedance curves due to having a very low Q. Eg: a 2200uFcap with ESR of 10mohms at 100kHz. Q = reactance / resistance = .0007 /.01 = 0.07 .... Phil |
Electrolytic ESR verus temperature test
"William Sommer****** = ****head " ** FFS asshole STOP removing the CONTEXT !!!!!!!!!! -------------------------------------------------------------- tinkerbell" First manufacturers learned how to make almost perfect stuff. Remember the TV sets working for 20 years or more. ** No, that was never the case. I've had a Sony and an NAD that lasted 20 years. ** Statements like that are stupid and worthless. Examples ONLY count as evidence if they are of common knowledge. The TRUTH is that manufactures NEVER learned how to make "almost perfect stuff " and that TV sets were never anything of the sort. I had a colour TV set that " lasted " 24 years - made by Pye here in Sydney. Just needed a bit of service every couple of years and re-gunned tube to cover the last 10. In its last year, it was probably the longest surviving set of that make in the country. So ****ing what ? .... Phil |
Electrolytic ESR verus temperature test
On Tue, 9 Jul 2013 11:50:30 +1000, "Phil Allison"
wrote: "Jeff Liebermann is bad at math" Close. I'm horrible at math. Even worse, I usually get it right the first time, but then change it to something wrong during double checking. Thanks for the correction. ** How about 40* (300/5)^2 = 144,000 uF Oops(tm). Checking, both the 40 uF 300 v and the 144,000 uF 5V caps can store 1.8 joules. But energy storage is simply NOT the issue. Electros used at the output of SMPSs are there to suppress ripple voltage down to a few mV at currents of many amps. So their impedance at frequencies between 20kHz and 100KHz must be as low as possible. Agreed. If I think of the ripple voltage in terms of percent of the operating voltage, I get an odd result. The 5V power supply probably wants 50mv of ripple or less for 1% regulation: http://www.imcpower.com/prodigit/an_403.htm Scaled to 300V, that would be: 300 / 5 * 50mv = 3.0 V of ripple which would be awful. That makes the filtering requirements for high voltage power supply more stringent than a low voltage power supply. I would have expected the opposite. Modern electros in the thousands of uF have very low, broad impedance curves due to having a very low Q. Eg: a 2200uFcap with ESR of 10mohms at 100kHz. Q = reactance / resistance = .0007 /.01 = 0.07 Good point. How to measure ESR and lead inductance with pulse generator and a scope. http://www.emcesd.com/tt020100.htm More fun, with parallel resonant capacitors: http://www.users.on.net/~glenk/capacitor/capacitor.htm -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Jeff Liebermann is bad at math
"Jeff Liebermann is bad at math" Close. I'm horrible at math. Even worse, I usually get it right the first time, but then change it to something wrong during double checking. Thanks for the correction. ** How about 40* (300/5)^2 = 144,000 uF But energy storage is simply NOT the issue. Electros used at the output of SMPSs are there to suppress ripple voltage down to a few mV at currents of many amps. So their impedance at frequencies between 20kHz and 100KHz must be as low as possible. Agreed. If I think of the ripple voltage in terms of percent of the operating voltage, I get an odd result. The 5V power supply probably wants 50mv of ripple or less for 1% regulation: http://www.imcpower.com/prodigit/an_403.htm Scaled to 300V, that would be: 300 / 5 * 50mv = 3.0 V of ripple which would be awful. That makes the filtering requirements for high voltage power supply more stringent than a low voltage power supply. I would have expected the opposite. ** Really ? Then FFS compare apples with apples: Linear, line frequency DC supplies can be simple, well filtered or regulated: 1. Simple = bridge plus electro. 2. Well filtered = bridge, electro, inductor and another electro. 3. Regulated = bridge, electro, pass transistor and control circuit or regulator IC. In the last case, the output voltage is steady with line and load changes and there is almost no ripple. ---------------------------------- The Switch Mode case: SMPSs electronically regulate against line variations, load variations and line frequency ripple on the incoming DC. But crucially, they can do NOTHING about ripple voltage ( after rectification) at the *switching frequency* - that job is done by passive filtering using just electros and small inductors. The electro's value is NOT chosen cos you need large numbers of uFs for it to work - it IS chosen for its high frequency ESR value and ripple rating - plus the fact it will have a low Q. Look at any table of similar voltage electros and see how the ESR figure goes down as the uFs go up. If one electro will not do, then use two or more in parallel to get the ESR and ripple current rating you want. Simple. .... Phil |
Jeff Liebermann is bad at math
"The electro's value is NOT chosen cos you need large numbers of uFs for it
to work - it IS chosen for its high frequency ESR value and ripple rating - plus the fact it will have a low Q. " The values are also chosen for an orderly power down. In many devices you don't want, for example, the 5V line to slam down while the 3.3V line is still up. Sometimes it doesn't matter, sometimes it does. Also sometimes even though one larger value cap would work, but they'll use more in parallel because of ripple current. Having been burned a few too many times I just bridge in caps in a PS and see if the unit comes up. If so I replace all of them in any given bank. however during the time when there is only one (good) cap in the circuit it will get quite hot, even during a few minutes of testing. I've had a couple get almost too hot to touch when running like that. |
Electrolytic ESR verus temperature test
Remember the TV sets working for 20 years or more.
On Monday, July 8, 2013 4:42:15 PM UTC-4, Phil Allison wrote: ** No, that was never the case. I do agree with one thing; anecdotal evidence from a couple of examples doesn't mean squat. I don't know about Australia Phil, but here in the States, TVs made in the 80s were extraordinarily reliable. U.S., Japan, and even the Korean models were reliable. Indiana built RCAs such as the 10X series (except early production, bad epoxy in flybacks), the 12X, the 13X series ran from new to the end of their lives, most of them never needing any sort of repair. We sold tons of these, gave a three year warranty at no charge (in house warranty), and had just one fail within the three years. When these were traded in later for big CRT models, most had never been serviced or required anything more than basic cabinet cleaning\detailing and grey scale\focusing to be put out in the used TV department where they were again sold with a one year warranty, despite being well past 10 years old. I will concede that these were far simpler TVs that those that came later in 90s, but we never saw wholesale capacitor failures or crappy solder either. |
Electrolytic ESR verus temperature test
Agreed. If I think of the ripple voltage in terms of percent of the operating voltage, I get an odd result. The 5V power supply probably wants 50mv of ripple or less for 1% regulation: http://www.imcpower.com/prodigit/an_403.htm Scaled to 300V, that would be: 300 / 5 * 50mv = 3.0 V of ripple which would be awful. That makes the filtering requirements for high voltage power supply more stringent than a low voltage power supply. I would have expected the opposite. The power supplies in guitar tube amps are universally linear. Simple transformer, full wave rectifier, reservoir cap followed by L-C or R-C filtering. Rails up to 500v can typically be found feeding the output stage, and it's not at all unusual to see ripple voltages of 5 volts or more on these high voltage rails. The hum on the output is barely noticeable, and just makes it sound like a 'tube amp'. The rails feeding the front end tend to be somewhat lower in voltage, and often have several stages of R-C filtering ahead of them, and as a result, tend to be rather 'quieter' in terms of residual ripple voltage. Arfa |
Electrolytic ESR verus temperature test
Arfa Daily wrote: "Michael A. Terrell" wrote in message m... Arfa Daily wrote: "Michael A. Terrell" wrote in message m... Arfa Daily wrote: I haven't had a chance yet to fully examine your results links, but I thought that I would just wade in to say that your last observation is very common with other equipment such as TV sets, and indeed switchmode power supplies in general. I see examples of this most every week where a piece of equipment has a power supply that only goes to a standby mode when the owner of the equipment switches it "off". Then they go on holiday, and switch it off for real, and when they come back and try to start it up again - nothing. And the cause is always bad electros that were fine when they were kept warm but went too high on their ESR to fulfill their circuit function, when thy fully cooled. Has anyone tried one of these $18 ESR meters? http://www.ebay.com/itm/190859294488 I recently bought one of the similar ones that has component testing on it as well as ESR http://www.ebay.co.uk/itm/1810723297... 4.m1439.l2648 Don't you love that they never bother to mount the LCDs in these designs? and I have to say that it works very well. ESR function agrees nicely with my Bob Parker The original, or the newer one? I have the original, bought as a kit. The original, also bought as a kit. Did you see the other post that I did today that detailed a comparison between the Bob P and the little Chinese job on a faulty cap that I had cause to replace ? Arfa This? -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-* As a matter of particular interest to Michael T, I hung the faulty one across the little Chinese component tester that I mentioned elsewhere in the thread. That made it 42 ohms, so pretty good agreement with Bob's meter. But what was also of note was the fact that the tester showed it to have a value of 44.6 uF, so not far from its nominal 47uF, even though it was clearly well out of spec on its ESR. This underlines what we have discussed on here before in that you cannot determine the condition of an electrolytic by measuring its capacitance alone. It has to have its ESR checked to get a meaningful result, and that is best, and most conveniently, done with a proper in-circuit ESR meter, that's designed for the job. -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-* I've seen very high capacitance readings on failing electrolytics, on some cheap meters. About 20 years ago, I went through my inventory of caps and chuck any electrolytics that read higher than specs. When I got the ESR meter and built it, I tossed another 20%. Being in my 60s, some parts were made in the '40s since I had bought out a number of old shops in the '70s & '80s. ;-) The cap you described was just starting to fail. First, the ESR starts to rise, then the capacitance drops as it dries out, even more. I used to do some failure analysis on components at one plant. |
Electrolytic ESR verus temperature test
"Michael A. Terrell" wrote in message m... Arfa Daily wrote: "Michael A. Terrell" wrote in message m... Arfa Daily wrote: "Michael A. Terrell" wrote in message m... Arfa Daily wrote: I haven't had a chance yet to fully examine your results links, but I thought that I would just wade in to say that your last observation is very common with other equipment such as TV sets, and indeed switchmode power supplies in general. I see examples of this most every week where a piece of equipment has a power supply that only goes to a standby mode when the owner of the equipment switches it "off". Then they go on holiday, and switch it off for real, and when they come back and try to start it up again - nothing. And the cause is always bad electros that were fine when they were kept warm but went too high on their ESR to fulfill their circuit function, when thy fully cooled. Has anyone tried one of these $18 ESR meters? http://www.ebay.com/itm/190859294488 I recently bought one of the similar ones that has component testing on it as well as ESR http://www.ebay.co.uk/itm/1810723297... 4.m1439.l2648 Don't you love that they never bother to mount the LCDs in these designs? and I have to say that it works very well. ESR function agrees nicely with my Bob Parker The original, or the newer one? I have the original, bought as a kit. The original, also bought as a kit. Did you see the other post that I did today that detailed a comparison between the Bob P and the little Chinese job on a faulty cap that I had cause to replace ? Arfa This? -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-* As a matter of particular interest to Michael T, I hung the faulty one across the little Chinese component tester that I mentioned elsewhere in the thread. That made it 42 ohms, so pretty good agreement with Bob's meter. But what was also of note was the fact that the tester showed it to have a value of 44.6 uF, so not far from its nominal 47uF, even though it was clearly well out of spec on its ESR. This underlines what we have discussed on here before in that you cannot determine the condition of an electrolytic by measuring its capacitance alone. It has to have its ESR checked to get a meaningful result, and that is best, and most conveniently, done with a proper in-circuit ESR meter, that's designed for the job. -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-* I've seen very high capacitance readings on failing electrolytics, on some cheap meters. About 20 years ago, I went through my inventory of caps and chuck any electrolytics that read higher than specs. When I got the ESR meter and built it, I tossed another 20%. Being in my 60s, some parts were made in the '40s since I had bought out a number of old shops in the '70s & '80s. ;-) The cap you described was just starting to fail. First, the ESR starts to rise, then the capacitance drops as it dries out, even more. I used to do some failure analysis on components at one plant. Yes, that was the post, and yes, I think you are right that the cap was in early stage failure. For sure, it showed no external signs of stress Arfa |
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