Hi maybe you are pointing at perfectly fine performing PA-7AII amplifier 🙂
I would rather suspect the preamp, the Bluesound Node 2i and/or SMSL SU-8S if these are always used as sources. Why?
1. The PA-7AII amplifier has been checked by an experienced tech.
2. No words on the preamp that might have bad caps?!
3. Especially NAD uses mediocre electrolytic caps that don't have a long useful life. NAD devices are prone to errors and known for mediocre or even bad quality parts!
4. The SU-8S is apparently known for plops but this might be an unrelated issue. https://www.audiosciencereview.com/...pops-and-clicks-on-track-format-change.11612/
If brownouts, blackouts and whatnot are normal in your area then overvoltage will not be far away either I think. You would do your sensitive equipment a favor by permanently adding a known good fused power distributor that has mains filtering combined with MOVs for overvoltage protection. Such a distributor can be DIYed with excellent results. The name on it is not important, it is important that it really comes into action when overvoltage occurs and that the filtering is adequate.
There is a definite need for PE for safety and correct working of the filtering. Of course you have PE as the Nakamichi devices have 3 prong IEC connectors and 3 wire cables.
I would rather suspect the preamp, the Bluesound Node 2i and/or SMSL SU-8S if these are always used as sources. Why?
1. The PA-7AII amplifier has been checked by an experienced tech.
2. No words on the preamp that might have bad caps?!
3. Especially NAD uses mediocre electrolytic caps that don't have a long useful life. NAD devices are prone to errors and known for mediocre or even bad quality parts!
4. The SU-8S is apparently known for plops but this might be an unrelated issue. https://www.audiosciencereview.com/...pops-and-clicks-on-track-format-change.11612/
If brownouts, blackouts and whatnot are normal in your area then overvoltage will not be far away either I think. You would do your sensitive equipment a favor by permanently adding a known good fused power distributor that has mains filtering combined with MOVs for overvoltage protection. Such a distributor can be DIYed with excellent results. The name on it is not important, it is important that it really comes into action when overvoltage occurs and that the filtering is adequate.
There is a definite need for PE for safety and correct working of the filtering. Of course you have PE as the Nakamichi devices have 3 prong IEC connectors and 3 wire cables.
Last edited:
Hi jean-paul,
I actually do know why it is popping and exactly what to do while also avoiding other service issues that will soon appear if they haven't already.
The service procedure is conceptually straight forward, however skill is needed to do this, and other related things while you work on it. When I get one, I follow the same time consuming actions and end up with an improved (reliability) amplifier that does not exhibit any further problems.
Nakamichi used very good parts - capacitors included. However the amplifier does run warm and some installations trap heat. Every part has a service life that is accelerated by heat. So some work is straight service and some preventative in nature. There are things you do need to be careful of while working on them. I have had to undo damage done by other repair people, so I really do know.
-Chris
I actually do know why it is popping and exactly what to do while also avoiding other service issues that will soon appear if they haven't already.
The service procedure is conceptually straight forward, however skill is needed to do this, and other related things while you work on it. When I get one, I follow the same time consuming actions and end up with an improved (reliability) amplifier that does not exhibit any further problems.
Nakamichi used very good parts - capacitors included. However the amplifier does run warm and some installations trap heat. Every part has a service life that is accelerated by heat. So some work is straight service and some preventative in nature. There are things you do need to be careful of while working on them. I have had to undo damage done by other repair people, so I really do know.
-Chris
The amplifier has been checked but what when it are the sources that suffered from the brownout? NAD is not so good with parts.
The brownout had zero to do with anything. This fault can be very intermittent, they all exhibit the same issues at this age and the question is are they actually acting up or not. If they are serviced it will solve this issue and / or prevent it. Period.
NAD is total garbage from my standpoint, but most brands are these days. Early NAD was very poor quality, and one newer model I just looked at (well regarded) isn't very good either.
NAD is total garbage from my standpoint, but most brands are these days. Early NAD was very poor quality, and one newer model I just looked at (well regarded) isn't very good either.
Cheers, everyone -- I wasn't getting notifications on replies to the thread over the weekend, so I'm super happy to see so much input on my issue this Monday morning.
@jean-paul -- I have ruled out the BlueSound & SMSL as the Nakamichi rig, and its problem, has been replicated on a different transport and DAC (Chromecast audio & SMSL SU-1) in a different room. To boot, I ruled out my main analog source, as my other room uses a Yamaha TT.
@rayma -- I have the Nakamichi plugged into a Furman PST-8. No change in the noise at all.
@anatech -- Thank you for your time and your insight on this issue. An earlier exploration of my issue on AK concurred with transistors as the likely culprit; I did not get this fully investigated. Without having looked at my particular unit, how are bad transistors identified? What about parts availability? If I swap out one pair, would it be analogous to changing just two bad tires of a different brand?
I am based in the Los Angeles area, and wonder if anyone here has a lead on someone near me (within 100 miles, let's say) that could assist.
@jean-paul -- I have ruled out the BlueSound & SMSL as the Nakamichi rig, and its problem, has been replicated on a different transport and DAC (Chromecast audio & SMSL SU-1) in a different room. To boot, I ruled out my main analog source, as my other room uses a Yamaha TT.
@rayma -- I have the Nakamichi plugged into a Furman PST-8. No change in the noise at all.
@anatech -- Thank you for your time and your insight on this issue. An earlier exploration of my issue on AK concurred with transistors as the likely culprit; I did not get this fully investigated. Without having looked at my particular unit, how are bad transistors identified? What about parts availability? If I swap out one pair, would it be analogous to changing just two bad tires of a different brand?
I am based in the Los Angeles area, and wonder if anyone here has a lead on someone near me (within 100 miles, let's say) that could assist.
Hi avantbored,
There are some transistor types that are changed - and they should be matched. The hFE function on a meter doesn't cut it. Other things as well.
The PCB traces are overheated and you need to take care removing the old parts. You really want to protect these amps (any good equipment), so find a careful (probably older) audio service technician. There should be someone in your area. These days you have to be careful who does your work, most "techs" are real hacks! I'm in my mid-60s and probably in the last decade of properly trained technicians. I haven't trained anyone since about 1996, I sold my shop in 1998. Really good technicians were always rare, now we are an endangered species - lol!
Most current techs do not take the care and attention to service equipment without damaging the PCB, they don't even know to match parts. They also do not invest in good bench equipment or stay current (you must!). The person you are looking for will be picky and exacting, will use new parts only from authorized distribution and have up-to-date equipment on their bench. Good brands of equipment. They will have an audio analyzer and a good THD meter (Mine are HP and ShibaSoku, I use an RTX analyzer). They will have very good meters and equipment to properly measure raw components. Most of my equipment is HP / Agilent / Keysight - you don't want to know how much it is worth. If the tech works with junk, works quickly or is really cheap - RUN! Your choice, but good audio equipment should run decades and decades giving you top performance with occasional service.
One idiot can destroy your equipment to the point where it may never be reliable or operate even to manufacture's spec. Normally equipment will beat those numbers comfortably. The entire point of a sound system is to enjoy it. If it never works properly, how can you do that and what is it worth no matter the name on the faceplate?
-Chris
There are some transistor types that are changed - and they should be matched. The hFE function on a meter doesn't cut it. Other things as well.
The PCB traces are overheated and you need to take care removing the old parts. You really want to protect these amps (any good equipment), so find a careful (probably older) audio service technician. There should be someone in your area. These days you have to be careful who does your work, most "techs" are real hacks! I'm in my mid-60s and probably in the last decade of properly trained technicians. I haven't trained anyone since about 1996, I sold my shop in 1998. Really good technicians were always rare, now we are an endangered species - lol!
Most current techs do not take the care and attention to service equipment without damaging the PCB, they don't even know to match parts. They also do not invest in good bench equipment or stay current (you must!). The person you are looking for will be picky and exacting, will use new parts only from authorized distribution and have up-to-date equipment on their bench. Good brands of equipment. They will have an audio analyzer and a good THD meter (Mine are HP and ShibaSoku, I use an RTX analyzer). They will have very good meters and equipment to properly measure raw components. Most of my equipment is HP / Agilent / Keysight - you don't want to know how much it is worth. If the tech works with junk, works quickly or is really cheap - RUN! Your choice, but good audio equipment should run decades and decades giving you top performance with occasional service.
One idiot can destroy your equipment to the point where it may never be reliable or operate even to manufacture's spec. Normally equipment will beat those numbers comfortably. The entire point of a sound system is to enjoy it. If it never works properly, how can you do that and what is it worth no matter the name on the faceplate?
-Chris
Hi jean-paul,
Right, sure. I see equipment new that performs well and is made well. It isn't cheap.
The sad truth is that properly serviced older equipment often outperforms many new systems easily. And it does at lower cost. Nothing is cheap, especially these days.
Example, right now I am rebuilding a Sansui AU-517 for someone near and dear to my heart. I've just started and already have performance well beyond what it started as after I got it working (and it beat spec). When I am done the performance will be well beyond what Sansui produced, and it will easily outperform most new equipment. Then as a final insult, this is made more robustly and will in fact easily outlast a new piece.
So, that's your advice? Hmmm ....
Right, sure. I see equipment new that performs well and is made well. It isn't cheap.
The sad truth is that properly serviced older equipment often outperforms many new systems easily. And it does at lower cost. Nothing is cheap, especially these days.
Example, right now I am rebuilding a Sansui AU-517 for someone near and dear to my heart. I've just started and already have performance well beyond what it started as after I got it working (and it beat spec). When I am done the performance will be well beyond what Sansui produced, and it will easily outperform most new equipment. Then as a final insult, this is made more robustly and will in fact easily outlast a new piece.
So, that's your advice? Hmmm ....
Well maybe not in thought and it is not an advice but the common way of dealing with this. Truth is that new devices often cost less than repairing old stuff. Technology is too volatile these days and prices of parts are high for private customers. If one can find the parts that is. Not to mention a repair guy when it is specialty stuff.
After having cheap devices outperforming classic devices too many times I don’t bother to have/repair old supposedly high quality stuff anymore. A large part is marketing and perception, reality is that it is old and had its best time. What IMO can’t be beat is the mechanical quality and quality of the casings of old equipment.
After having cheap devices outperforming classic devices too many times I don’t bother to have/repair old supposedly high quality stuff anymore. A large part is marketing and perception, reality is that it is old and had its best time. What IMO can’t be beat is the mechanical quality and quality of the casings of old equipment.
Last edited:
Well, you know cheap doesn't make any sense. If you adjust the prices to todays pricing, that old equipment is more than worth maintaining. I'll be honest, being a practicing technician, most new equipment is absolutely not worth owning at any price point.
Good service expensive? yeah - of course! Now, I want to see you attempt to make a new piece last with the same quality of an older 1980's piece plus or minus 5 years manufacture. We're talking good equipment of course. Now how much do you think that would cost?
I think I just more than made my point.
Good service expensive? yeah - of course! Now, I want to see you attempt to make a new piece last with the same quality of an older 1980's piece plus or minus 5 years manufacture. We're talking good equipment of course. Now how much do you think that would cost?
I think I just more than made my point.
Apparently the average consumer thinks otherwise.
I scrap eighties stuff but reuse transformers, full/solid aluminium knobs and extension rods etc. Mechanical quality of old stuff with todays electronics is a good combination and one creates something. Destruction is the mother of creation 😉
I scrap eighties stuff but reuse transformers, full/solid aluminium knobs and extension rods etc. Mechanical quality of old stuff with todays electronics is a good combination and one creates something. Destruction is the mother of creation 😉
Last edited:
Thanks so much, anatech, for this info and the engagement on my thread. I have a couple people in mind to call who were your contemporaries and know their way around an amp and measuring equipment (Tom Ishimoto, who was at Nikko developing the all FET-based components, and I have already exchanged emails, but he's passing on my Nak).
My regular tech does this only on the side, and his main source of income, a production company, really started to take off around the time he was rebuilding some KEF crossovers for me. I will also ask him if he wishes to take this Nak on (he fixed a resistor in the protection circuit that, at failure, sent some DC to a Wharfedale tweeter...), but will also inquire if the other two people I have in mind could take it on.
I'd have no idea about how to find documentation about any shops from this period in Nakamichi history who performed warranty work are still around. I have some ideas (the original boxes still have the sticker from the store -- RSL!) and perhaps the paperwork might lead me somewhere. Any other ideas?
If this Nak did not have so much sentimental value for me, I wouldn't be investing as many dollars into it as I have; I fret over the ~2mm raw aluminum on the edge of the handle that couldn't have been helped (the thing is heavy...). I hear what you're saying when it comes to the cost of newer devices; I think you are pointing to larger economic and historical around industrialized manufacturing advancements that are important to consider. Don't want to digress too much, but whenever someone tells me a story about a "Genius" tech at the Apple store saying that the whole logic board needs to be replaced, my eyes roll and my blood pressure rises slightly. It is no wonder that "Right to Repair" conversations in the US and EU have become more mainstream in the ensuing decade when products that cost $3k cannot last longer than 3 years without glitches, or whose hardware is so inscrutable that it's not worth repairing at the warranty servicer. It is also no wonder that a niche market of laptop manufacturers that cater to people like me (and perhaps like us) has cropped up now, offering to consumers the chance to choose their own parts (from a curated selection) rather than pre-baked goods.
Hi jean-paul,
People are lazy and cheap as a rule. They always take the easy way out almost every single time.
However, the lazy part comes in where they did not think or research to see where their decisions would lead. I have often said that we (as a group) voted with our dollars. Greed at the supplier / manufacturing level jumped at this chance and made it seem like it was a good thing for us. Now we have exactly what we voted for - and none of us like it! This actually costs us more than it would have, and performance is lower. Yeah us! Way to go!
The right choice is seldom the easy of cheap choice at the time. Long term, these are easier and cheaper choices (doing the right thing) but we are accustomed to thinking short term it was easy to lead us all down that path.
It's too bad you are willing to destroy a good example of equipment just for a cheap source of parts. Sounds familiar I guess. Technology? Properly used we can make better stuff, but in practivce we do not, and the junk we do make will not even last. Sadly, this earth cannot afford these choices. When did we become so selfish and stupid?
Just because te bulk of people make the wrong and ill informed decisions doesn't make it right.
People are lazy and cheap as a rule. They always take the easy way out almost every single time.
However, the lazy part comes in where they did not think or research to see where their decisions would lead. I have often said that we (as a group) voted with our dollars. Greed at the supplier / manufacturing level jumped at this chance and made it seem like it was a good thing for us. Now we have exactly what we voted for - and none of us like it! This actually costs us more than it would have, and performance is lower. Yeah us! Way to go!
The right choice is seldom the easy of cheap choice at the time. Long term, these are easier and cheaper choices (doing the right thing) but we are accustomed to thinking short term it was easy to lead us all down that path.
It's too bad you are willing to destroy a good example of equipment just for a cheap source of parts. Sounds familiar I guess. Technology? Properly used we can make better stuff, but in practivce we do not, and the junk we do make will not even last. Sadly, this earth cannot afford these choices. When did we become so selfish and stupid?
Just because te bulk of people make the wrong and ill informed decisions doesn't make it right.
Hi avantbored,
All I will say is that I repair many of these, restoring proper performance that will last. I do the same thing for other examples of good equipment. I don't restore junk or poorly designed equipment.
Value? Give it some thought before answering. What is something worth? Buying the same make / model used gives you something needing the same work. Sum zero plan. Okay, more intelligently then. How much is something with equivalent performance and durability going to cost (obviously new)? Gee, now there is a different question entirely! All of a sudden, proper service becomes a much more intelligent course of action. Physics hasn't changed, no features that are truly useful can be added.
I look at new gear all the time. So far I only see ghastly expensive products that perform better with the same (hopefully) expected service life. The extremely expensive equipment is worse though. Poorly designed as a rule, and underperforming. So throwing money at the problem doesn't seem to be a responsible answer.
All I will say is that I repair many of these, restoring proper performance that will last. I do the same thing for other examples of good equipment. I don't restore junk or poorly designed equipment.
Value? Give it some thought before answering. What is something worth? Buying the same make / model used gives you something needing the same work. Sum zero plan. Okay, more intelligently then. How much is something with equivalent performance and durability going to cost (obviously new)? Gee, now there is a different question entirely! All of a sudden, proper service becomes a much more intelligent course of action. Physics hasn't changed, no features that are truly useful can be added.
I look at new gear all the time. So far I only see ghastly expensive products that perform better with the same (hopefully) expected service life. The extremely expensive equipment is worse though. Poorly designed as a rule, and underperforming. So throwing money at the problem doesn't seem to be a responsible answer.
@anatech, To your point about value, I agree entirely. I am the only audio enthusiast amongst my friends (at least when it comes to learning about gear and buying/selling components), and their eyes widened when I told them how much my recap service cost on the Nak. I told them exactly as you have: The comparative component would cost many more times than I could afford. So definitely, repair for me has always been a solid option.
Hi avantbored,
Sorry, I should have addressed the second paragraph to everyone in general. I wasn't pointing at you specifically. More to comments made by jean-paul.
Most times the main filter capacitors are fine. The seals are better and there is more electrolyte inside them. Other capacitors are not in areas where they are stressed unless the environment is hot. "Recaps" often cause more damage than they fix, and it isn't uncommon for those folks to use not great capacitors or kits off Ebay. Any kind of service must be approached with intelligence. Also, if the leads do not fit the spacing EXACTLY, they need to be formed properly so as not to damage the rubber seal. Almost no one does this because it takes too long, and they are too cheap to buy a part that fits. Some capacitors do need replacement, like in your PA-7. That's because it is hot in there. But the large capacitors are generally fine. People who replace filter capacitors also don't use ones as good as the originals.
Translation, avoid equipment that has been totally "recapped". It generally will not be done well. You'd be further ahead with the originals.
Sorry, I should have addressed the second paragraph to everyone in general. I wasn't pointing at you specifically. More to comments made by jean-paul.
Most times the main filter capacitors are fine. The seals are better and there is more electrolyte inside them. Other capacitors are not in areas where they are stressed unless the environment is hot. "Recaps" often cause more damage than they fix, and it isn't uncommon for those folks to use not great capacitors or kits off Ebay. Any kind of service must be approached with intelligence. Also, if the leads do not fit the spacing EXACTLY, they need to be formed properly so as not to damage the rubber seal. Almost no one does this because it takes too long, and they are too cheap to buy a part that fits. Some capacitors do need replacement, like in your PA-7. That's because it is hot in there. But the large capacitors are generally fine. People who replace filter capacitors also don't use ones as good as the originals.
Translation, avoid equipment that has been totally "recapped". It generally will not be done well. You'd be further ahead with the originals.
Not wanting to react on anything but in my experience as a tech the filter caps are the caps that wear out most in normal circumstances. It is the small value caps that survive the years. If they become bad often the rectifier diodes have become a liability. So it is wise to replace both. In hot devices one can safely assume recapping will solve todays and tomorrows issues that may follow as a result of aging. A normal person uses quality parts otherwise it would not make too much sense to replace the original ones at all. Anyone with experience and feel for quality work can do it. It is not rocket science only to be carried out by special techs. What does happen is that totally clueless persons do such things. They post here for answers on their self created problems 🙂
Electrolytic caps are the worst part in electronics as they do wear out so replacement is normal after 25+ years. The main challenge is to find good quality today as a replacement as longevity is not exactly a key parameter at some electronic part manufacturers.
Then the potentiometers, the switches...... I know as I have been repairing such famous old stuff and then one only sees the broken and worn out ones that after an expensive repair are surpassed by todays class D amplifiers. Out with the old and in with the new!
Electrolytic caps are the worst part in electronics as they do wear out so replacement is normal after 25+ years. The main challenge is to find good quality today as a replacement as longevity is not exactly a key parameter at some electronic part manufacturers.
Then the potentiometers, the switches...... I know as I have been repairing such famous old stuff and then one only sees the broken and worn out ones that after an expensive repair are surpassed by todays class D amplifiers. Out with the old and in with the new!
Last edited:
Hi jean-paul,
I agree with you to a point. My main concern is the health of the equipment. Most people do not form the leads on capacitors properly. Do you, or do you just jam them in?
I test every part before installing it, and also the "bad" ones. I have done this for decades to get an accurate feel for reality. In good equipment most coupling capacitors are perfectly fine and measure as good as new ones. I normally test at 1 KHz and 10 KHz for smaller values. For large filter capacitors I'll disagree with you. I look at the ripple waveform with my scope and the small details of that waveform. I have compared with new ones if the customer insisted. So my advice comes from decades of experimentation and observation using HP test equipment (not cheap off-brand stuff).
In some equipment, Pioneer is an easy example, most capacitors are simply horrible quality. A total "recap" sadly makes perfect sense. Doing this to a Marantz is probably hurting the Marantz.
Yes, electrolytic capacitors are the most failure-prone component, and they have improved a great deal over the years. 1970's vintage average capacitors can be improved on, but the better ones really hold up against new stuff.
The smaller electrolytic capacitors in power supplies take a beating and are often not in the best of health. But those have normal rubber seals like small capacitors, not the much better seals the large capacitors have. That and they are often in higher temperature locations, which really hits reliability hard.
I would say that replacing capacitors means you use your brain. If they ran hot and had high ripple current - yes. But a coupling cap in a tone control circuit in good equipment will be in great shape 99% of the time. This is where a trained tech has the advantage, and also there are sometimes new types that perform better. Again, an experienced tech can properly select the correct capacitor type for the job at hand. Anyone can replace capacitors as long as the following is true. They know how to desolder and solder properly (that isn't the case normally) and they have decent equipment to do so. Secondly, they know how to form the leads properly so a not to damage the seal (it takes a few years to fail, so everyone thinks they did a great job). Thirdly, they are following proper advice as to what type of capacitor to use.
Replacing coupling capacitors will only fix a problem if there is one. It will not improve sound quality, and the things that do are not talked about normally by people who do know. So if you're going to rip out a bunch of caps to improve sound, just stop. You will not achieve your goal unless you stumble over a defective capacitor, and you may well damage your equipment while wasting a bunch of time and money. If you're going to buy a "cap kit", may as well flush the money down the drain. What you are installing is probably poor quality and even the wrong values.
Not everyone is a good lawyer or accountant or mechanic. We can perform some tasks, but those people are trained and do a better job. Same for playing technician.
-Chris
I agree with you to a point. My main concern is the health of the equipment. Most people do not form the leads on capacitors properly. Do you, or do you just jam them in?
I test every part before installing it, and also the "bad" ones. I have done this for decades to get an accurate feel for reality. In good equipment most coupling capacitors are perfectly fine and measure as good as new ones. I normally test at 1 KHz and 10 KHz for smaller values. For large filter capacitors I'll disagree with you. I look at the ripple waveform with my scope and the small details of that waveform. I have compared with new ones if the customer insisted. So my advice comes from decades of experimentation and observation using HP test equipment (not cheap off-brand stuff).
In some equipment, Pioneer is an easy example, most capacitors are simply horrible quality. A total "recap" sadly makes perfect sense. Doing this to a Marantz is probably hurting the Marantz.
Yes, electrolytic capacitors are the most failure-prone component, and they have improved a great deal over the years. 1970's vintage average capacitors can be improved on, but the better ones really hold up against new stuff.
The smaller electrolytic capacitors in power supplies take a beating and are often not in the best of health. But those have normal rubber seals like small capacitors, not the much better seals the large capacitors have. That and they are often in higher temperature locations, which really hits reliability hard.
I would say that replacing capacitors means you use your brain. If they ran hot and had high ripple current - yes. But a coupling cap in a tone control circuit in good equipment will be in great shape 99% of the time. This is where a trained tech has the advantage, and also there are sometimes new types that perform better. Again, an experienced tech can properly select the correct capacitor type for the job at hand. Anyone can replace capacitors as long as the following is true. They know how to desolder and solder properly (that isn't the case normally) and they have decent equipment to do so. Secondly, they know how to form the leads properly so a not to damage the seal (it takes a few years to fail, so everyone thinks they did a great job). Thirdly, they are following proper advice as to what type of capacitor to use.
Replacing coupling capacitors will only fix a problem if there is one. It will not improve sound quality, and the things that do are not talked about normally by people who do know. So if you're going to rip out a bunch of caps to improve sound, just stop. You will not achieve your goal unless you stumble over a defective capacitor, and you may well damage your equipment while wasting a bunch of time and money. If you're going to buy a "cap kit", may as well flush the money down the drain. What you are installing is probably poor quality and even the wrong values.
Not everyone is a good lawyer or accountant or mechanic. We can perform some tasks, but those people are trained and do a better job. Same for playing technician.
-Chris
So is it an actual bad transistor, or intermittent solder joint/contact that’s the root cause of this particular crack n pop? I know of several transistor types/families to avoid like the plague because they tend to go bad for no good reason (Like those STK modules do, sometimes for the same “no reason”).