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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Kenwood L-1000T , 1990
Expensive looking fm tuner not keeping stations etc in memory. Not fully
dismantled as quite a workup to get to the stage of getting to the C11 supercap with only 1/4V on it. Anyone aware of anything else that needs changing as a lot of normal electros on the Vdd line through different parts of the kit. I will change the fractional farad (if I can find such a squat one) but how to test these to confirm it is failed? charge to 5V and time discharge through an R but what sort of value , high enough not to phase it , and low enough for reasonable time to 2.5V? ESR I imagine is irrelevant. Schematic is on e-service |
#2
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Kenwood L-1000T, 1990
If there's only 1/4 volt across the supercap, what's the cause? Is the
charging voltage low, or is the cap leaky/shorted? For testing, I'd try charging the cap through 100 ohms or so. That should give a time constant in a range suitable for following along on your DVM. Unless you have zero vertical clearance, a replacement cap can be mounted just about anywhere. The lead length doesn't matter. |
#3
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Kenwood L-1000T, 1990
"William Sommerwerck" wrote in message ... If there's only 1/4 volt across the supercap, what's the cause? Is the charging voltage low, or is the cap leaky/shorted? For testing, I'd try charging the cap through 100 ohms or so. That should give a time constant in a range suitable for following along on your DVM. Unless you have zero vertical clearance, a replacement cap can be mounted just about anywhere. The lead length doesn't matter. You should know that these types of capacitors have an extremely high internal series resistance so the internal resistance would swamp out 100 ohms and make the measurement useless. Low ESR is not needed since they only need to supply micro-amps when called to duty. David |
#4
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Kenwood L-1000T, 1990
For testing, I'd try charging the cap through 100 ohms
or so. That should give a time constant in a range suitable for following along on your DVM. You should know that these types of capacitors have an extremely high internal series resistance so the internal resistance would swamp out 100 ohms and make the measurement useless. I once replaced a nicad battery in a tuner with a supercap, fed through about 5K. The capacitor charges up quickly, which does not suggest an extremely high series internal resistance. (I can check this, if you like. The tuner is in my bedroom.) The Wikipedia article says that EDLCs have a very high /power/ density -- that is, they can deliver their stored energy very quickly. This is inconsistent with an extremely high series internal resistance. In fact, the article lists the following advantage... "Extremely low internal resistance (ESR) and consequent high cycle efficiency (95% or more) and extremely low heating levels." |
#5
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Kenwood L-1000T, 1990
William Sommerwerck wrote in message
... If there's only 1/4 volt across the supercap, what's the cause? Is the charging voltage low, or is the cap leaky/shorted? For testing, I'd try charging the cap through 100 ohms or so. That should give a time constant in a range suitable for following along on your DVM. Unless you have zero vertical clearance, a replacement cap can be mounted just about anywhere. The lead length doesn't matter. Wiring across from the cavernous central space makes sense. The very squat form factor of the original may well have precipitated its failure. I was forgetting about all the diodes along the power rail route so only one nearby standard electro (assuming the diodes are ok) |
#6
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Kenwood L-1000T, 1990
On 10/10/2010 1:17 PM, William Sommerwerck wrote:
For testing, I'd try charging the cap through 100 ohms or so. That should give a time constant in a range suitable for following along on your DVM. You should know that these types of capacitors have an extremely high internal series resistance so the internal resistance would swamp out 100 ohms and make the measurement useless. I once replaced a nicad battery in a tuner with a supercap, fed through about 5K. The capacitor charges up quickly, which does not suggest an extremely high series internal resistance. (I can check this, if you like. The tuner is in my bedroom.) The Wikipedia article says that EDLCs have a very high /power/ density -- that is, they can deliver their stored energy very quickly. This is inconsistent with an extremely high series internal resistance. In fact, the article lists the following advantage... "Extremely low internal resistance (ESR) and consequent high cycle efficiency (95% or more) and extremely low heating levels." I may be wrong, but I think that we're confusing 'high internal resistance' and 'leakage resistance'. Internal resistance would be in series with the capacitor. Leakage resistance would be across the capacitor, causing it to discharge. |
#7
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Kenwood L-1000T, 1990
"William Sommerwerck" wrote in message ... For testing, I'd try charging the cap through 100 ohms or so. That should give a time constant in a range suitable for following along on your DVM. You should know that these types of capacitors have an extremely high internal series resistance so the internal resistance would swamp out 100 ohms and make the measurement useless. The Wikipedia article says that EDLCs have a very high /power/ density -- that is, they can deliver their stored energy very quickly. This is inconsistent with an extremely high series internal resistance. In fact, the article lists the following advantage... "Extremely low internal resistance (ESR) and consequent high cycle efficiency (95% or more) and extremely low heating levels." Note that we are not talking about super-caps here but memory backup capacitors that are very small considering their capacitance and CV^2 value. Super capacitors are a very different chemistry and for a different purpose entirely. David |
#8
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Kenwood L-1000T, 1990
William Sommerwerck wrote in message
... For testing, I'd try charging the cap through 100 ohms or so. That should give a time constant in a range suitable for following along on your DVM. You should know that these types of capacitors have an extremely high internal series resistance so the internal resistance would swamp out 100 ohms and make the measurement useless. I once replaced a nicad battery in a tuner with a supercap, fed through about 5K. The capacitor charges up quickly, which does not suggest an extremely high series internal resistance. (I can check this, if you like. The tuner is in my bedroom.) The Wikipedia article says that EDLCs have a very high /power/ density -- that is, they can deliver their stored energy very quickly. This is inconsistent with an extremely high series internal resistance. In fact, the article lists the following advantage... "Extremely low internal resistance (ESR) and consequent high cycle efficiency (95% or more) and extremely low heating levels." I was not aware of the promising automotive use of supercaps, safe ultra-fast charge etc |
#9
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Kenwood L-1000T, 1990
We are not talking about super-caps here but memory
backup capacitors that are very small considering their capacitance and CV^2 value. Super capacitors are a very different chemistry and for a different purpose entirely. Are you certain? A "conventional" cap would not be able to retain the memory very long. You need something 0.1F or larger -- and conventional caps rarely come in that size. I installed a supercap in my Lux tuner, and it holds the memory two or three days. |
#10
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Kenwood L-1000T, 1990
William Sommerwerck Inscribed thus:
We are not talking about super-caps here but memory backup capacitors that are very small considering their capacitance and CV^2 value. Super capacitors are a very different chemistry and for a different purpose entirely. Are you certain? A "conventional" cap would not be able to retain the memory very long. You need something 0.1F or larger -- and conventional caps rarely come in that size. I installed a supercap in my Lux tuner, and it holds the memory two or three days. I would concur with William. I have a 0.22F @ 5v on my desk at the moment, it holds its charge for many days. -- Best Regards: Baron. |
#11
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Kenwood L-1000T, 1990
"Baron" wrote in message
... William Sommerwerck Inscribed thus: We are not talking about super-caps here but memory backup capacitors that are very small considering their capacitance and CV^2 value. Super capacitors are a very different chemistry and for a different purpose entirely. Are you certain? A "conventional" cap would not be able to retain the memory very long. You need something 0.1F or larger -- and conventional caps rarely come in that size. I installed a supercap in my Lux tuner, and it holds the memory two or three days. I would concur with William. I have a 0.22F @ 5v on my desk at the moment, it holds its charge for many days. -- Best Regards: Baron. Lets get things correct here. Memory backup capacitors can have very high capacitance values and extremely low leakage. That is not in dispute. The term supercap does not refer to the typical memory capacitor installed on consumer electronics equipment. That is a different type that has high series resistance. If you have a ESR meter, measure one for yourself but discharge it first for a long time. David |
#12
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Kenwood L-1000T, 1990
David Inscribed thus:
"Baron" Â*wrote in message ... William Sommerwerck Inscribed thus: We are not talking about super-caps here but memory backup capacitors that are very small considering their capacitance and CV^2 value. Super capacitors are a very different chemistry and for a different purpose entirely. Are you certain? A "conventional" cap would not be able to retain the memory very long. You need something 0.1F or larger -- and conventional caps rarely come in that size. I installed a supercap in my Lux tuner, and it holds the memory two or three days. I would concur with William. I have a 0.22F @ 5v on my desk at the moment, it holds its charge for many days. Best Regards: Baron. Lets get things correct here. Memory backup capacitors can have very high capacitance values and extremely low leakage. That is not in dispute. The term supercap does not refer to the typical memory capacitor installed on consumer electronics equipment. That is a different type that has high series resistance. If you have a ESR meter, measure one for yourself but discharge it first for a long time. David Thanks for your note. Yes the cap I have is intended for memory retention service. I do have an ESR meter but it hadn't occurred to me to actually measure it, though I do take your point about discharging it first. I did discharge it some time ago and was surprised by how much the voltage had recovered the following day. -- Best Regards: Baron. |
#13
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Kenwood L-1000T, 1990
Lets get things correct here. Memory backup capacitors can have
very high capacitance values and extremely low leakage. That is not in dispute. The term supercap does not refer to the typical memory capacitor installed on consumer electronics equipment. That is a different type that has high series resistance. If you have a ESR meter, measure one for yourself but discharge it first for a long time. I'm not sure what the "typical" memory capacitor is. With respect to my Lux 5T50, the cap was one I selected and installed. |
#14
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Kenwood L-1000T, 1990
William Sommerwerck Inscribed thus:
Lets get things correct here. Memory backup capacitors can have very high capacitance values and extremely low leakage. That is not in dispute. The term supercap does not refer to the typical memory capacitor installed on consumer electronics equipment. That is a different type that has high series resistance. If you have a ESR meter, measure one for yourself but discharge it first for a long time. I'm not sure what the "typical" memory capacitor is. With respect to my Lux 5T50, the cap was one I selected and installed. Hi William, I found references to "Super Cap" on EPCOS website. http://www.epcos.com/inf/20/25/ds/b32330_b32332_450.pdf Not quite what I expected. -- Best Regards: Baron. |
#15
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Kenwood L-1000T, 1990
I found references to "Super Cap" on EPCOS website.
http://www.epcos.com/inf/20/25/ds/b32330_b32332_450.pdf Not quite what I expected. This is an AC starter cap -- dubbed a Super Motor Cap. Not the same thing. |
#16
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Kenwood L-1000T, 1990
Old 0.047F , 5.5V dropped from about 5V to 1V in about 1 sec with DVM load.
Replacement .2F one , connected to 5V ps via 220R took 35 sec to rise from 3V to 4V |
#17
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Kenwood L-1000T, 1990
Baron Inscribed thus:
David Inscribed thus: I would concur with William. I have a 0.22F @ 5v on my desk at the moment, it holds its charge for many days. Best Regards: Baron. Lets get things correct here. Memory backup capacitors can have very high capacitance values and extremely low leakage. That is not in dispute. The term supercap does not refer to the typical memory capacitor installed on consumer electronics equipment. That is a different type that has high series resistance. If you have a ESR meter, measure one for yourself but discharge it first for a long time. David Thanks for your note. Yes the cap I have is intended for memory retention service. I do have an ESR meter but it hadn't occurred to me to actually measure it, though I do take your point about discharging it first. I did discharge it some time ago and was surprised by how much the voltage had recovered the following day. Just and update: I got the marked value wrong, its 2.2F @ 5v. There is no indication of the manufacturer. I've currently got a 4.5v 60ma torch bulb connected across it to discharge it. It took a few seconds for the bulb to stop glowing. Anyway I'm going to leave it overnight and check its ESR tomorrow. It should be well and truly discharged by then. -- Best Regards: Baron. |
#18
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Kenwood L-1000T, 1990
William Sommerwerck wrote:
Lets get things correct here. Memory backup capacitors can have very high capacitance values and extremely low leakage. That is not in dispute. The term supercap does not refer to the typical memory capacitor installed on consumer electronics equipment. That is a different type that has high series resistance. If you have a ESR meter, measure one for yourself but discharge it first for a long time. I'm not sure what the "typical" memory capacitor is. With respect to my Lux 5T50, the cap was one I selected and installed. for something like that from 1990, it would most likely be a cap made by Elna (quite likely dark blue) NEC (possibly green) or Panasonic (all sorts of colors). Standard Oil was even making them at the time. Also, they didn't have 'low' ESR supercaps like they do now, so ignore any crap off wikipedia or comparisons to modern datasheets for products that look the same. |
#19
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Kenwood L-1000T, 1990
I'm not sure what the "typical" memory capacitor is. With respect
to my Lux 5T50, the cap was one I selected and installed. For something like that from 1990, it would most likely be a cap made by Elna (quite likely dark blue) NEC (possibly green) or Panasonic (all sorts of colors). Standard Oil was even making them at the time. Try 1980. I don't remember the brand, but I don't think it was any of these. Regardless of what you do or don't think, IT WORKS. The storage time -- when the tuner is turned off and left off -- is about 40% of the original tiny nicad battery the supercap replaced (3 days versus a week). This seems reasonable, and is consistent with the information given in the Wikipedia article. Also, they didn't have "low" ESR supercaps like they do now, so ignore any crap off Wikipedia or comparisons to modern datasheets for products that look the same. I don't think anyone here knows what they're talking about. I'm certainly aware of my own ignorance. |
#20
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Kenwood L-1000T, 1990
Cydrome Leader wrote in message
... William Sommerwerck wrote: Lets get things correct here. Memory backup capacitors can have very high capacitance values and extremely low leakage. That is not in dispute. The term supercap does not refer to the typical memory capacitor installed on consumer electronics equipment. That is a different type that has high series resistance. If you have a ESR meter, measure one for yourself but discharge it first for a long time. I'm not sure what the "typical" memory capacitor is. With respect to my Lux 5T50, the cap was one I selected and installed. for something like that from 1990, it would most likely be a cap made by Elna (quite likely dark blue) NEC (possibly green) or Panasonic (all sorts of colors). Standard Oil was even making them at the time. Also, they didn't have 'low' ESR supercaps like they do now, so ignore any crap off wikipedia or comparisons to modern datasheets for products that look the same. I discharged overnight an NEC U6 265 green, 0.2F, 5.5V and got an ESR of 5.6R |
#21
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Kenwood L-1000T, 1990
Baron Inscribed thus:
Baron Inscribed thus: David Inscribed thus: I would concur with William. I have a 0.22F @ 5v on my desk at the moment, it holds its charge for many days. Best Regards: Baron. Lets get things correct here. Memory backup capacitors can have very high capacitance values and extremely low leakage. That is not in dispute. The term supercap does not refer to the typical memory capacitor installed on consumer electronics equipment. That is a different type that has high series resistance. If you have a ESR meter, measure one for yourself but discharge it first for a long time. David Thanks for your note. Yes the cap I have is intended for memory retention service. I do have an ESR meter but it hadn't occurred to me to actually measure it, though I do take your point about discharging it first. I did discharge it some time ago and was surprised by how much the voltage had recovered the following day. Just and update: I got the marked value wrong, its 2.2F @ 5v. There is no indication of the manufacturer. I've currently got a 4.5v 60ma torch bulb connected across it to discharge it. It took a few seconds for the bulb to stop glowing. Anyway I'm going to leave it overnight and check its ESR tomorrow. It should be well and truly discharged by then. Following up: The ESR measures 10-11 ohms (last digit can't make up its mind). Peak charge current from a 5v 0.5ohm source hits 480ma (AVO 8 on 1A range) before rapidly dropping to zero. Four hours later the terminal voltage is still 5V (Advance 10Mopv meter). -- Best Regards: Baron. |
#22
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Kenwood L-1000T, 1990
N_Cook Inscribed thus:
Cydrome Leader wrote in message ... William Sommerwerck wrote: Lets get things correct here. Memory backup capacitors can have very high capacitance values and extremely low leakage. That is not in dispute. The term supercap does not refer to the typical memory capacitor installed on consumer electronics equipment. That is a different type that has high series resistance. If you have a ESR meter, measure one for yourself but discharge it first for a long time. I'm not sure what the "typical" memory capacitor is. With respect to my Lux 5T50, the cap was one I selected and installed. for something like that from 1990, it would most likely be a cap made by Elna (quite likely dark blue) NEC (possibly green) or Panasonic (all sorts of colors). Standard Oil was even making them at the time. Also, they didn't have 'low' ESR supercaps like they do now, so ignore any crap off wikipedia or comparisons to modern datasheets for products that look the same. I discharged overnight an NEC U6 265 green, 0.2F, 5.5V and got an ESR of 5.6R That's about half of the value I measured. -- Best Regards: Baron. |
#23
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Kenwood L-1000T, 1990
"baron" wrote in message
... Baron Inscribed thus: Baron Inscribed thus: David Inscribed thus: I would concur with William. I have a 0.22F @ 5v on my desk at the moment, it holds its charge for many days. Best Regards: Baron. Lets get things correct here. Memory backup capacitors can have very high capacitance values and extremely low leakage. That is not in dispute. The term supercap does not refer to the typical memory capacitor installed on consumer electronics equipment. That is a different type that has high series resistance. If you have a ESR meter, measure one for yourself but discharge it first for a long time. David Thanks for your note. Yes the cap I have is intended for memory retention service. I do have an ESR meter but it hadn't occurred to me to actually measure it, though I do take your point about discharging it first. I did discharge it some time ago and was surprised by how much the voltage had recovered the following day. Just and update: I got the marked value wrong, its 2.2F @ 5v. There is no indication of the manufacturer. I've currently got a 4.5v 60ma torch bulb connected across it to discharge it. It took a few seconds for the bulb to stop glowing. Anyway I'm going to leave it overnight and check its ESR tomorrow. It should be well and truly discharged by then. Following up: The ESR measures 10-11 ohms (last digit can't make up its mnd). Peak charge current from a 5v 0.5ohm source hits 480ma (AVO 8 on 1A range) before rapidly dropping to zero. Four hours later the terminal voltage is still 5V (Advance 10Mopv meter). -- Best Regards: Baron. You have a good one with 10 ohms. The 10 - 15 year old ones had much higher ESR even when new but still low leakage. David |
#24
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Kenwood L-1000T, 1990
David Inscribed thus:
"baron" wrote in message ... Baron Inscribed thus: Baron Inscribed thus: David Inscribed thus: I would concur with William. I have a 0.22F @ 5v on my desk at the moment, it holds its charge for many days. Best Regards: Baron. Lets get things correct here. Memory backup capacitors can have very high capacitance values and extremely low leakage. That is not in dispute. The term supercap does not refer to the typical memory capacitor installed on consumer electronics equipment. That is a different type that has high series resistance. If you have a ESR meter, measure one for yourself but discharge it first for a long time. David Thanks for your note. Yes the cap I have is intended for memory retention service. I do have an ESR meter but it hadn't occurred to me to actually measure it, though I do take your point about discharging it first. I did discharge it some time ago and was surprised by how much the voltage had recovered the following day. Just and update: I got the marked value wrong, its 2.2F @ 5v. There is no indication of the manufacturer. I've currently got a 4.5v 60ma torch bulb connected across it to discharge it. It took a few seconds for the bulb to stop glowing. Anyway I'm going to leave it overnight and check its ESR tomorrow. It should be well and truly discharged by then. Following up: The ESR measures 10-11 ohms (last digit can't make up its mnd). Peak charge current from a 5v 0.5ohm source hits 480ma (AVO 8 on 1A range) before rapidly dropping to zero. Four hours later the terminal voltage is still 5V (Advance 10Mopv meter). -- Best Regards: Baron. You have a good one with 10 ohms. The 10 - 15 year old ones had much higher ESR even when new but still low leakage. David Wow ! Thanks. :-) Apart from playing with it yesterday, its sat on my bench for weeks looking for something to do... -- Best Regards: Baron. |
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