Very poor electros ...
Had a Rega Elex hifi amp fetch up on the bench today. It was low on one
channel compared to the other. On a 'scope, both channels looked a bit scruffy at the output, as well. Both channels were the same level and reasonably clean at the volume control. It's a fully discrete power amp south of the volume control, and nothing was obviously wrong in the bad channel. So just for sport, I picked up the ESR meter with a view to giving all the caps a quick read. The first one that I put the meter across, was quite close to the driver transistors, and it went over 60 ohms. Ah-ha thought I. Got it ! I checked the cap on the opposite side of the circuit near to the complementary driver, and it too had a high ESR. Putting this down to them being near to components that probably ran pretty warm, I didn't think a lot more about it, and just went ahead and replaced them. That restored the level of the 'bad' channel - to TWICE the level of the 'good' channel. At that point, the alarm bells started to ring. There are only three values of cap used - 2.2 uF, 10 uF and 22 uF. Curiously, they are all marked with the same "C" numbers on the board, i.e. all of the 10 u's are called "C8", the 22u's are "C10" and the 2.2u's are "C9". Anyway, I started to measure them all, and every single one, in both channels, is either high ESR or completely open. Over 20 caps in all. I've pulled them all out, and re-measured them out of circuit, and the state of them is confirmed. I hadn't got enough in stock, so I've got some more coming tomorrow. Most of them are not located near to hot-running components, so I'm at a bit of a loss to explain how that many caps all go bad. It will be interesting to see how much better the amp performs when all of the caps are replaced, and whether the scruffiness of the output waveform will be improved. Arfa |
Very poor electros ...
On Thu, 16 May 2013 02:25:09 +0100, "Arfa Daily"
wrote: Anyway, I started to measure them all, and every single one, in both channels, is either high ESR or completely open. Over 20 caps in all. Most likely they are all counterfeit parts. You can sometimes recognize them by various differences from the real parts, but what I'm seeing is that the counterfeits are getting closer to the real thing. http://www.badcaps.net/wiki/index.php?title=Counterfeit_Capacitor https://www.google.com/search?q=capacitor+fake&tbm=isch https://www.google.com/search?q=capacitor+counterfeit&tbm=isch My collection: http://802.11junk.com/jeffl/pics/repair/bad-caps.jpg -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Very poor electros ...
"Jeff Liebermann = FOOL " "Arfa Daily" wrote: Anyway, I started to measure them all, and every single one, in both channels, is either high ESR or completely open. Over 20 caps in all. Most likely they are all counterfeit parts. ** Utter horse manure. .... Phil |
Very poor electros ...
In article ,
Arfa Daily wrote: Most of them are not located near to hot-running components, so I'm at a bit of a loss to explain how that many caps all go bad. Could they date to the "stolen partial electrolyte formula" era? My recollection is that caps made with the defective electrolyte tend to start going gnaester-upwards after a few thousand hours with power applied... I don't recall heat being a requirement for the failure to occur. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
Very poor electros ...
"Dave Platt" Arfa Daily Most of them are not located near to hot-running components, so I'm at a bit of a loss to explain how that many caps all go bad. Could they date to the "stolen partial electrolyte formula" era? ** Q. Why was that formula stolen ?? A. Because it was the secret to making tiny, high value and LOW ESR electros for use in PC mobos and SMPS. Not for low value, regular electros in audio. ...... Phil |
Very poor electros ...
Jeff Liebermann wrote:
On Thu, 16 May 2013 02:25:09 +0100, "Arfa Daily" wrote: Anyway, I started to measure them all, and every single one, in both channels, is either high ESR or completely open. Over 20 caps in all. Most likely they are all counterfeit parts. You can sometimes recognize them by various differences from the real parts, but what I'm seeing is that the counterfeits are getting closer to the real thing. http://www.badcaps.net/wiki/index.php?title=Counterfeit_Capacitor https://www.google.com/search?q=capacitor+fake&tbm=isch https://www.google.com/search?q=capacitor+counterfeit&tbm=isch My collection: http://802.11junk.com/jeffl/pics/repair/bad-caps.jpg Ha, I like the green "Rifeking" branded ones. |
Very poor electros ...
Arfa Daily wrote in message
... Had a Rega Elex hifi amp fetch up on the bench today. It was low on one channel compared to the other. On a 'scope, both channels looked a bit scruffy at the output, as well. Both channels were the same level and reasonably clean at the volume control. It's a fully discrete power amp south of the volume control, and nothing was obviously wrong in the bad channel. So just for sport, I picked up the ESR meter with a view to giving all the caps a quick read. The first one that I put the meter across, was quite close to the driver transistors, and it went over 60 ohms. Ah-ha thought I. Got it ! I checked the cap on the opposite side of the circuit near to the complementary driver, and it too had a high ESR. Putting this down to them being near to components that probably ran pretty warm, I didn't think a lot more about it, and just went ahead and replaced them. That restored the level of the 'bad' channel - to TWICE the level of the 'good' channel. At that point, the alarm bells started to ring. There are only three values of cap used - 2.2 uF, 10 uF and 22 uF. Curiously, they are all marked with the same "C" numbers on the board, i.e. all of the 10 u's are called "C8", the 22u's are "C10" and the 2.2u's are "C9". Anyway, I started to measure them all, and every single one, in both channels, is either high ESR or completely open. Over 20 caps in all. I've pulled them all out, and re-measured them out of circuit, and the state of them is confirmed. I hadn't got enough in stock, so I've got some more coming tomorrow. Most of them are not located near to hot-running components, so I'm at a bit of a loss to explain how that many caps all go bad. It will be interesting to see how much better the amp performs when all of the caps are replaced, and whether the scruffiness of the output waveform will be improved. Arfa What date? All same make ? |
Very poor electros ...
On Thu, 16 May 2013 13:53:49 +1000, "Phil Allison"
wrote: "Jeff Liebermann = FOOL " "Arfa Daily" wrote: Anyway, I started to measure them all, and every single one, in both channels, is either high ESR or completely open. Over 20 caps in all. Most likely they are all counterfeit parts. ** Utter horse manure. ... Phil Fake Panasonic caps: http://www.youtube.com/watch?v=yKPyf7O8Uyg http://www.panasonic.com/industrial/electronic-components/tertiary-navigation/product-information/alerts.aspx http://www.badcaps.net/forum/showthread.php?t=13259 http://www.badcaps.net/forum/showthread.php?t=14047 (Registration required to view photos). Fake Rubycon: http://www.youtube.com/watch?v=g9E-CXVFQ0M Nichicon: http://www.shenzhen-standard.com/2010/09/13/beware-of-counterfeit-capacitor-products/ The Japanese manufacturers parts are being cloned by some Chinese manufacturers. I've seen my share of both flavors of fake parts, mostly bought on eBay but also extracted from repairs. General interest: http://www.hardwaresecrets.com/printpage/How-to-Identify-Japanese-Electrolytic-Capacitors/595 http://www.capacitorindustry.com/the-facts-about-counterfeiting-cant-be-ignored http://www.ebnonline.com/author.asp?section_id=2467&doc_id=250412 http://www.ebnonline.com/author.asp?section_id=1084&doc_id=247776 Incidentally, it's not just capacitors. Lubricants: http://www.shenzhen-standard.com/2011/03/31/police-seized-boxes-of-counterfeit-lubricants/ Lamps: http://www.best-news.us/news-4407218-Taiyuan-seized-a-large-number-of-counterfeit-international-brand-lamps-involved-more-than-500-million.html Misc: http://counterfeitparts.wordpress.com http://www.cbp.gov/xp/cgov/newsroom/news_releases/national/01092012.xml -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Very poor electros ...
"Jeff Liebermann = IDIOT " "Phil Allison" "Jeff Liebermann = FOOL " "Arfa Daily" Anyway, I started to measure them all, and every single one, in both channels, is either high ESR or completely open. Over 20 caps in all. Most likely they are all counterfeit parts. ** Utter horse manure. ... Phil Fake Panasonic caps: ** FFS you TENTH WITTED JERK OFF !!! Fake caps exist, but AD's are NOT likely to be examples. The values are too low, for a start. .... Phil |
Very poor electros ...
"Phil Allison" wrote in message ... "Jeff Liebermann = IDIOT " "Phil Allison" "Jeff Liebermann = FOOL " "Arfa Daily" Anyway, I started to measure them all, and every single one, in both channels, is either high ESR or completely open. Over 20 caps in all. Most likely they are all counterfeit parts. ** Utter horse manure. ... Phil Fake Panasonic caps: ** FFS you TENTH WITTED JERK OFF !!! Fake caps exist, but AD's are NOT likely to be examples. The values are too low, for a start. ... Phil Yes, I don't think it is because they are fakes. They are made by a company called Eurocap. I have never heard of them before. The amp is actually quite old, so I guess you could argue that they had reached the end of their specced life. However, looking again at it today, it's one of those designs where the entire case is a diecast heatsink, and there are no ventilation slots at all. I suppose that the interior probably heats up quite a bit when the amp is doing some work, and it is this that has led to the demise of all the caps. I did the replacement today, and ran the ESR meter over them all again out of circuit. The 2.2 u's were fairly consistent at around 16 ohms. The new replacements were about 1.5 ohms. Not one of the 10u's and 22u's was less than 60 ohms, and several were completely open. Once they had all been replaced, both channels had identical output, and the sine wave I put in it now came out totally clean. Arfa |
Very poor electros ...
"N_Cook" wrote in message ... Arfa Daily wrote in message ... Had a Rega Elex hifi amp fetch up on the bench today. It was low on one channel compared to the other. On a 'scope, both channels looked a bit scruffy at the output, as well. Both channels were the same level and reasonably clean at the volume control. It's a fully discrete power amp south of the volume control, and nothing was obviously wrong in the bad channel. So just for sport, I picked up the ESR meter with a view to giving all the caps a quick read. The first one that I put the meter across, was quite close to the driver transistors, and it went over 60 ohms. Ah-ha thought I. Got it ! I checked the cap on the opposite side of the circuit near to the complementary driver, and it too had a high ESR. Putting this down to them being near to components that probably ran pretty warm, I didn't think a lot more about it, and just went ahead and replaced them. That restored the level of the 'bad' channel - to TWICE the level of the 'good' channel. At that point, the alarm bells started to ring. There are only three values of cap used - 2.2 uF, 10 uF and 22 uF. Curiously, they are all marked with the same "C" numbers on the board, i.e. all of the 10 u's are called "C8", the 22u's are "C10" and the 2.2u's are "C9". Anyway, I started to measure them all, and every single one, in both channels, is either high ESR or completely open. Over 20 caps in all. I've pulled them all out, and re-measured them out of circuit, and the state of them is confirmed. I hadn't got enough in stock, so I've got some more coming tomorrow. Most of them are not located near to hot-running components, so I'm at a bit of a loss to explain how that many caps all go bad. It will be interesting to see how much better the amp performs when all of the caps are replaced, and whether the scruffiness of the output waveform will be improved. Arfa What date? All same make ? The amp dates from the mid nineties, and yes, all made by Eurocap, who I had never heard of Arfa |
Very poor electros ...
On Fri, 17 May 2013 02:39:15 +0100, "Arfa Daily"
wrote: Yes, I don't think it is because they are fakes. They are made by a company called Eurocap. I have never heard of them before. Me too. However, it's a real company: http://www.eurocap-int.com/ http://www.eurocap-int.com/main/electidx.htm Still, you might want to compare photos of the electrolytics on the data sheets with those you extracted. The amp is actually quite old, so I guess you could argue that they had reached the end of their specced life. However, looking again at it today, it's one of those designs where the entire case is a diecast heatsink, and there are no ventilation slots at all. Overheating will certainly boil off the electrolyte. That may explain the massive capacitor failures. See any evidence of venting on the electrolytics? Look at the base as well as the top. I suppose that the interior probably heats up quite a bit when the amp is doing some work, and it is this that has led to the demise of all the caps. When you get it working, give it a burn in test. If the original caps were any good when new, your replacements will probably have a similar lifetime. I did the replacement today, and ran the ESR meter over them all again out of circuit. The 2.2 u's were fairly consistent at around 16 ohms. The new replacements were about 1.5 ohms. Not one of the 10u's and 22u's was less than 60 ohms, and several were completely open. Once they had all been replaced, both channels had identical output, and the sine wave I put in it now came out totally clean. Nicely done. Got time for an accelerated burn-in test? -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Very poor electros ...
Arfa Daily wrote:
"N_Cook" wrote in message ... Arfa Daily wrote in message ... Had a Rega Elex hifi amp fetch up on the bench today. It was low on one channel compared to the other. On a 'scope, both channels looked a bit scruffy at the output, as well. Both channels were the same level and reasonably clean at the volume control. It's a fully discrete power amp south of the volume control, and nothing was obviously wrong in the bad channel. So just for sport, I picked up the ESR meter with a view to giving all the caps a quick read. The first one that I put the meter across, was quite close to the driver transistors, and it went over 60 ohms. Ah-ha thought I. Got it ! I checked the cap on the opposite side of the circuit near to the complementary driver, and it too had a high ESR. Putting this down to them being near to components that probably ran pretty warm, I didn't think a lot more about it, and just went ahead and replaced them. That restored the level of the 'bad' channel - to TWICE the level of the 'good' channel. At that point, the alarm bells started to ring. There are only three values of cap used - 2.2 uF, 10 uF and 22 uF. Curiously, they are all marked with the same "C" numbers on the board, i.e. all of the 10 u's are called "C8", the 22u's are "C10" and the 2.2u's are "C9". Anyway, I started to measure them all, and every single one, in both channels, is either high ESR or completely open. Over 20 caps in all. I've pulled them all out, and re-measured them out of circuit, and the state of them is confirmed. I hadn't got enough in stock, so I've got some more coming tomorrow. Most of them are not located near to hot-running components, so I'm at a bit of a loss to explain how that many caps all go bad. It will be interesting to see how much better the amp performs when all of the caps are replaced, and whether the scruffiness of the output waveform will be improved. Arfa What date? All same make ? The amp dates from the mid nineties, and yes, all made by Eurocap, who I had never heard of Arfa it looks ike "eurocap" just imports stuff from the "far east" like a bunch of other "brands". |
Very poor electros ...
"Jeff Liebermann = OLD FOOL " Yes, I don't think it is because they are fakes. They are made by a company called Eurocap. I have never heard of them before. Me too. However, it's a real company: http://www.eurocap-int.com/ ** The web page says it has not been updated for almost six years. Methinks they are caputski. ..... Phil |
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