If I test at T5 I get around 9.5V, but there is no load to cause the voltage to drop across the 475 ohm resistor. If I put a 45ohm load across T5 to ground, the voltage goes down to the expected .77V.
To me, this indicates that the filament supply is working properly and the nutube failed prematurely.
To me, this indicates that the filament supply is working properly and the nutube failed prematurely.
To be fair this wouldn't be the first Nutube in this thread to have died an early death on its own. Things fail, and the DIYA store has policies for defects and manufacturers warrantees.
Korg seems to have production difficulties with obtaining consistent filament tension. It's the weakest part of the device design. I think that's why we are seeing forum issues come up around maximizing filament lifespan, etc.. Frankly, I'm surprised there haven't been more early filament failures.
Ringing seems to be caused by vibration induced into the filament. I have used 5 NuTubes in various projects so far and they all ring if tapped on, from almost no ringing to hyper sensitive. In one build, a Millet NuClassD amplifier, which has adjustable negative feedback, I solved a runaway ringing problem with a slight increase in the NFB levels. B1K really has no NFB (and you don't want it, I tried adding it and did not like the resultant sound character). So it's going to be more sensitive to tube production variations.
Ringing seems to be caused by vibration induced into the filament. I have used 5 NuTubes in various projects so far and they all ring if tapped on, from almost no ringing to hyper sensitive. In one build, a Millet NuClassD amplifier, which has adjustable negative feedback, I solved a runaway ringing problem with a slight increase in the NFB levels. B1K really has no NFB (and you don't want it, I tried adding it and did not like the resultant sound character). So it's going to be more sensitive to tube production variations.
After 48 years in the Auto Manufacturing field, deciding warranty coverage for 35 of those years, if someone handed me a "failed" part and it was NOT EXACTLY like "new" as in your shock scenario. The photo you posted where obvious internal defect was shown after use. I would have denied coverage as "abuse" with no concerns that the "national" office would override my decision.
Elwood625: I assume you worked for a US auto company. No wonder US auto companies have lost ground to the Japanese and now Korean companies. I mean, once a vehicle has been placed into service, every part is going to be subject to some wear. While I have had my share of issues with Toyota and Honda, there are nothing like what Iʻve had with Ford and Chrysler.
Say what you will, but people voted with their pocketbooks and were it not for truck sales, American car companies would be dead.
To be totally fair, all auto companies - domestic and foreign, have terrible policies with replacement parts: even if a designated service center provides the replacement part, the warranty is minimal - 30-90 days. Why is this? $$$$. This may be "industry standard, but it does not make it fair. I suppose, however, that the US consumer is ultimately at fault because the vast, vast majority are only concerned about first cost, and not long term value. reliability, and future availability of replacement parts.
Capitalism is broke internationally, but we are responsible. Sorry this is so far off the topic of DIY, folks, but I just canʻt help myself, especially as deicide67 expressed a reasonable - if arguable viewpoint. I just don't think the comeback was either respectful of well thought out (or well written for that matter; Iʻm still trying to puzzle out precisely what Elwood 625 means by "The photo you posted where obvious internal defect was shown after use.")
Say what you will, but people voted with their pocketbooks and were it not for truck sales, American car companies would be dead.
To be totally fair, all auto companies - domestic and foreign, have terrible policies with replacement parts: even if a designated service center provides the replacement part, the warranty is minimal - 30-90 days. Why is this? $$$$. This may be "industry standard, but it does not make it fair. I suppose, however, that the US consumer is ultimately at fault because the vast, vast majority are only concerned about first cost, and not long term value. reliability, and future availability of replacement parts.
Capitalism is broke internationally, but we are responsible. Sorry this is so far off the topic of DIY, folks, but I just canʻt help myself, especially as deicide67 expressed a reasonable - if arguable viewpoint. I just don't think the comeback was either respectful of well thought out (or well written for that matter; Iʻm still trying to puzzle out precisely what Elwood 625 means by "The photo you posted where obvious internal defect was shown after use.")
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I stand corrected on your employment.
As far as the issue of warranty, you certainly remember, given your age, that warranties were initially honored by the selling retailer - if they broke within a relatively short time period. The retailer would then return the item to the distributor/manufacturer for credit.
Today, because of the consumerʻs laser focus on first cost, the retailer is no longer on the hook unless they have consumer friendly return policies such as Bed, Bath and Beyond. And because of consumer abuse (!!!!!), even good stores have been forced to reduce their policies: L.L. Bean is the prime example. The new paradigm is contact the manufacturer directly for warranty service. That is OK so long as the company has good consumer support for warranty issues, which is not usually the case (again, because of $$$, inasmuch as a small number of consumers abuse the system and impose inordinate costs on the manufacturers).
Having said all that, please tell me how the individual DIY gets warranty service from Korg US for the NuTube. Go to their website and look for warranty info or service info.
OK, and for a final dose of reality, ordinal tubes almost never have anything more than a 30-60 days warranty and most are expressly sold without warranty for a variety of completely-understandable reasons, but also because the consumer is focused on first cost so sellers cannot economically provide reasonable return policies because they cannot make money when competing against the hundreds of other sellers out in the marketplace.
In sum, warranty support is a complex area with fault pointing everywhere. But Iʻd rather see a candid discussion of the issue rather than the one-sided brush-off.
As far as the issue of warranty, you certainly remember, given your age, that warranties were initially honored by the selling retailer - if they broke within a relatively short time period. The retailer would then return the item to the distributor/manufacturer for credit.
Today, because of the consumerʻs laser focus on first cost, the retailer is no longer on the hook unless they have consumer friendly return policies such as Bed, Bath and Beyond. And because of consumer abuse (!!!!!), even good stores have been forced to reduce their policies: L.L. Bean is the prime example. The new paradigm is contact the manufacturer directly for warranty service. That is OK so long as the company has good consumer support for warranty issues, which is not usually the case (again, because of $$$, inasmuch as a small number of consumers abuse the system and impose inordinate costs on the manufacturers).
Having said all that, please tell me how the individual DIY gets warranty service from Korg US for the NuTube. Go to their website and look for warranty info or service info.
OK, and for a final dose of reality, ordinal tubes almost never have anything more than a 30-60 days warranty and most are expressly sold without warranty for a variety of completely-understandable reasons, but also because the consumer is focused on first cost so sellers cannot economically provide reasonable return policies because they cannot make money when competing against the hundreds of other sellers out in the marketplace.
In sum, warranty support is a complex area with fault pointing everywhere. But Iʻd rather see a candid discussion of the issue rather than the one-sided brush-off.
Having posted after seeing the photos, I am curious, Elwood625, as to what you think one is to "more likely than not" conclude upon review of the images with respect to the cause of failure of the filament? This is probably the best standard (more likely than not) for the manufacturer, as opposed to the "preponderance of the evidence" standard in most civil litigation.
I personally do not know if this particular NuTube was abused in installation or operation. And I am also have a normal skepticism as to any claim by the user that they were not at fault, given that this is DIY. In keeping my mind open, I am trying to understand what elements in the photos give you cause to believe that the failure was due to user error..
Zero. Working Nutubes don't look like this, by your admission, it worked when you received it. Therefore, it didn't look like this when you received it. Let me guess, someone was poking at it saying "see it rings when you touch it, they call it microphonics."
Secret Warranties - The Center for Auto SafetyI do not see evidence showing how the tube looked before placed into operation. Accordingly, what is your basis for concluding "it didnʻt look like this when you received it?"
One possible alternative explanation, is that the NuTube was defective when placed into service - and looking exactly as shown, but the defect allowed operation for a time until it failed prematurely. There are other examples of such early failure even though the component works when first placed into service: insufficiently screened semiconductors placed into service which then fail; capacitors with poor film terminations that fail at duty currents, and so forth.
My own personal automotive story: Toyota Tercel, in service for several years, and then failed due to faulty ignition module. At the dealer, module replaced free because it was covered by a "secret warranty." As the Center for Auto Safety points out, secret warranties are a huge problem for consumers in the auto industry. No abuse on my part; the component worked for a time even though it was defective.
One possible alternative explanation, is that the NuTube was defective when placed into service - and looking exactly as shown, but the defect allowed operation for a time until it failed prematurely. There are other examples of such early failure even though the component works when first placed into service: insufficiently screened semiconductors placed into service which then fail; capacitors with poor film terminations that fail at duty currents, and so forth.
My own personal automotive story: Toyota Tercel, in service for several years, and then failed due to faulty ignition module. At the dealer, module replaced free because it was covered by a "secret warranty." As the Center for Auto Safety points out, secret warranties are a huge problem for consumers in the auto industry. No abuse on my part; the component worked for a time even though it was defective.
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Deicide67: by your own admission, this was shipped / transported elsewhere and was used by someone else, to whom you have (probably? Just assuming here) charged for the build. So you have to agree that the case for 100% certainty that the tube just went dead with no user / transportation abuse is hard to sell. Even you have not had the unit with you after it left your hands in working state. Can you vouch as to how it was treated by your client / friend?
Also, perhaps accusing the store, whom most of us know how great they treat customers (read this as “spoil” in the best sense!), very often losing money to have people happy and building things (it has happened to me a few times!) is not the best approach to win solidarity for your case. At least that is my take / opinion.
Rafa.
Also, perhaps accusing the store, whom most of us know how great they treat customers (read this as “spoil” in the best sense!), very often losing money to have people happy and building things (it has happened to me a few times!) is not the best approach to win solidarity for your case. At least that is my take / opinion.
Rafa.
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Secret warranties since then are paid using Goodwill $'s which is funded internally by Marketing. We would usually ask for participation in payment with the owner, yet rarely require it.
This has really been a neat conversation about warranty, liability and supply chain.
If you read my first post, I did not ask about opinions on any of that. I asked for test procedures. I received one which was poorly given at that since the circuit needs a filament to pull it down to the proper voltage. Supply V is about 9.1-9.5V from the zener source.
It’s two tubes being fed from a common supply. One channel is still doing perfectly fine and reads perfect voltage across the filament whereas the other has gone open.
Now, can someone provide test procedures for this?
Also, the recipient is a friend snd I don’t charge to assemble PCB kits to my friends.
If you read my first post, I did not ask about opinions on any of that. I asked for test procedures. I received one which was poorly given at that since the circuit needs a filament to pull it down to the proper voltage. Supply V is about 9.1-9.5V from the zener source.
It’s two tubes being fed from a common supply. One channel is still doing perfectly fine and reads perfect voltage across the filament whereas the other has gone open.
Now, can someone provide test procedures for this?
Also, the recipient is a friend snd I don’t charge to assemble PCB kits to my friends.
In the Korg Application Note (extract attached) it says "DO NOT exceed filament rating (0.7V 17mA)."
If your zener is putting out 9.5V as you said earlier, the steady state current through the cathode will be 18.41mA, surging perhaps to 19mA at startup (cold cathode).
I have no idea how critical the 17ma is, but the DO NOT is in all capital letters so I think the Korg board is designed assuming an honest 17mA maximum but due to zener tolerances on the B1K it can run higher. How much difference your 9.5V made, I have no idea, but it does seem to deliver more current than specified by Korg.
I was headed toward adding a constant current modification to my board until I realized that a) the cold cathode surge was pretty minimal and b) my own measured zener voltage is well below 9.0V so I am operating somewhere below 17mA in my preamp.
If your zener is putting out 9.5V as you said earlier, the steady state current through the cathode will be 18.41mA, surging perhaps to 19mA at startup (cold cathode).
I have no idea how critical the 17ma is, but the DO NOT is in all capital letters so I think the Korg board is designed assuming an honest 17mA maximum but due to zener tolerances on the B1K it can run higher. How much difference your 9.5V made, I have no idea, but it does seem to deliver more current than specified by Korg.
I was headed toward adding a constant current modification to my board until I realized that a) the cold cathode surge was pretty minimal and b) my own measured zener voltage is well below 9.0V so I am operating somewhere below 17mA in my preamp.
Attachments
Agree entirely!!!! Decide67, please carefully consider the totality of circumstances before deciding to seek a claim against DIY Audio Store. I am not saying you are right or wrong; I am asking for you to apply your best judgement and conscience in moving forward.