Hi Friends,
I'm more active on AK than here as I'm very much a novice, but eager to learn.
I have posted about the issue described below at that other forum with lots of help and insight, but just seeing other options here. Some brief background:
My thinking, then: Either it is some other thing on the circuit, the circuit itself and/or the outlet got damaged during the brownouts, or the Nak has some problem that has escaped three people.
Any thoughts or questions would be useful to me. I am most concerned about whether or not I should continue to run the Nak given the description of my issue.
Thanks all for your time,
Ryan
(PS. I'd wanted to write to @anatech, but as I'm so new here, I could not. I hope he spares some time, if he can.)
I'm more active on AK than here as I'm very much a novice, but eager to learn.
I have posted about the issue described below at that other forum with lots of help and insight, but just seeing other options here. Some brief background:
- My system: Nakamichi PA-7AII, CA7A, SL1700MK2, Bluesound Node 2i (into SMSL SU-8S).
- The chief complaint is as the title suggests: I have intermittent pops through both channels on all inputs with volume at 0% or 20%.
- I first noticed the issue after two short afternoon brownouts. The system was on, and the power cycled before I could switch it off. It was plugged directly into the wall.
- No noticeable issues -- no smoke, no change in sound, so I assumed the system was totally fine. Then I heard the pops, like static discharging.
- I have tried most troubleshooting tactics -- different outlets, different rooms; Amp/Preamp combos (more about this below)*, with or without a power conditioner (Furman PST-8).
- The amp has been serviced, mostly bias adjustments (and a resistor in protection circuit that fried).
- It was most recently by Jon Soderberg of Vintage Amp Repair (PCB recap, trimpots replaced). He gave it a clean bill of health and listened to it several times.
- The problem persists.
My thinking, then: Either it is some other thing on the circuit, the circuit itself and/or the outlet got damaged during the brownouts, or the Nak has some problem that has escaped three people.
Any thoughts or questions would be useful to me. I am most concerned about whether or not I should continue to run the Nak given the description of my issue.
Thanks all for your time,
Ryan
(PS. I'd wanted to write to @anatech, but as I'm so new here, I could not. I hope he spares some time, if he can.)
AC brownouts can be very bad for a lot of things in the home, but what I am thinking is that the brown out has caused something with one or more of your components. Wish that I had more.
The other thing that comes to mind is protecting your system from DC offset voltage on the incoming AC line. If nothing else it may be worth ruling out. Now that I think of it, I am presently trying to ignore a very small pop in the left channel of my system. Sigh, it never ends.
FWIW, three mechanics missed an AC problem with my truck. Got it back today all fixed. A leaky valve that should have been diagnosed before. The point here the same mechanic that fixed it today, missed it the time before. It can be right in front of your face, but invisible at the same time.
The other thing that comes to mind is protecting your system from DC offset voltage on the incoming AC line. If nothing else it may be worth ruling out. Now that I think of it, I am presently trying to ignore a very small pop in the left channel of my system. Sigh, it never ends.
FWIW, three mechanics missed an AC problem with my truck. Got it back today all fixed. A leaky valve that should have been diagnosed before. The point here the same mechanic that fixed it today, missed it the time before. It can be right in front of your face, but invisible at the same time.
If the same problem seems to happen with two different components, an external cause
is the most likely source. Brown outs can do damage to some equipment.
Some things to check for correlation: time of day or day of week; turn off other electronic devices;
HVAC system or other appliances operation.
There is some possibility that two of your components were damaged by the brownout, but this would be unusual.
is the most likely source. Brown outs can do damage to some equipment.
Some things to check for correlation: time of day or day of week; turn off other electronic devices;
HVAC system or other appliances operation.
There is some possibility that two of your components were damaged by the brownout, but this would be unusual.
Thanks for the input, rayma and lxnay.
@lxnay) wrote about DC offset on the incoming AC line. I am planning to get whole-house surge protection in the next couple of months, but I imagine this is different than what you're talking about.
I'm happy I got the Nak recapped with Jon, but the chasing continues. Now I am thinking whether or not there might be something to examine in the preamp?
@lxnay) wrote about DC offset on the incoming AC line. I am planning to get whole-house surge protection in the next couple of months, but I imagine this is different than what you're talking about.
I'm happy I got the Nak recapped with Jon, but the chasing continues. Now I am thinking whether or not there might be something to examine in the preamp?
I agree with the idea of whole house surge protection. It is a step in the right direction for protecting your home, but that isn't the same as DC offset in the AC line. I have to say that DC offset is not so likely to have caused your problem in my opinion, so I do apologize for including that as a possibility.
I do believe however that it is quite possible that a brownout in some sort of way, would not be good for most anything electrical or electronic, depending on its duration and level, not to mention what other crap/fuzz is on the incoming AC line while it is happening. To combat this would be yet another thing to tackle in spite of the opposite, which would be surge protection.
Whew. So, what you are now left with is the chase to find what is going on in the electronics that you are having this issue with. Again, that is assuming that all is well with the AC incoming line. Sorry that this goes in circles.
I do believe however that it is quite possible that a brownout in some sort of way, would not be good for most anything electrical or electronic, depending on its duration and level, not to mention what other crap/fuzz is on the incoming AC line while it is happening. To combat this would be yet another thing to tackle in spite of the opposite, which would be surge protection.
Whew. So, what you are now left with is the chase to find what is going on in the electronics that you are having this issue with. Again, that is assuming that all is well with the AC incoming line. Sorry that this goes in circles.
Right, it is going in circles!
Guess what I'm finding a bit odd is that I asked both of the techs that had my amp to run and re-run their listening tests, multiple ones, and neither of them heard it, which makes me think the outlet into which the components are usually plugged is a -- or the -- culprit. I do not know if there's any sense to that hypothesis, or even if it is one (more like paranoia?)
Guess what I'm finding a bit odd is that I asked both of the techs that had my amp to run and re-run their listening tests, multiple ones, and neither of them heard it, which makes me think the outlet into which the components are usually plugged is a -- or the -- culprit. I do not know if there's any sense to that hypothesis, or even if it is one (more like paranoia?)
The outlet doesn't necessarily have to be the problem, there's also EMI.
See if an AM radio in the room picks up noise at the same time.
An FM radio likely won't work though.
See if an AM radio in the room picks up noise at the same time.
An FM radio likely won't work though.
@rayma, I will track one down.
For anyone interested, I found my recording of the sound on my Google Drive, if you are curious. Move to 9:15; the pop is around 9:21. (https://drive.google.com/file/d/1NAlulca32rRk5DdjhE3ldpV09r0V9ap3/view?pli=1)
You may also hear the sound represented at this YT video, except in my case, I never hear it while music is playing. It's usually after I've listened to a side or something (pop at 0:20). The sound is very similar to mine, but his problem was solved by switching out his MC cart.
For anyone interested, I found my recording of the sound on my Google Drive, if you are curious. Move to 9:15; the pop is around 9:21. (https://drive.google.com/file/d/1NAlulca32rRk5DdjhE3ldpV09r0V9ap3/view?pli=1)
You may also hear the sound represented at this YT video, except in my case, I never hear it while music is playing. It's usually after I've listened to a side or something (pop at 0:20). The sound is very similar to mine, but his problem was solved by switching out his MC cart.
Just some suggestions from similar experience and complaints:
If an audio amplifier or system is crackling, popping intermittently etc. and regardless of the volume setting, your source is likely EMI picked up on the speaker leads. If the volume control won't change the level of the noise, it's a good indication that the noise is entering the power amp this way - via the back door and the power amplifier's feedback loop. Disconnecting your amplifier's signal input leads or selecting an unused input is usually good enough to check whether this is how the noise enters the system. Using very short speaker leads is another way to check this but probably inconvenient.
In quite a few cases, I've found periodic popping and crackling noise was actually caused by the solenoid power switches in freezers, refrigerators, air conditioners, stoves and other heavy current appliances in the home, which are often cycling on/off continuously . The contacts become damaged and they tend get noisier, emitting an increasing spray of EMI energy as they age, so YMMV.
If an audio amplifier or system is crackling, popping intermittently etc. and regardless of the volume setting, your source is likely EMI picked up on the speaker leads. If the volume control won't change the level of the noise, it's a good indication that the noise is entering the power amp this way - via the back door and the power amplifier's feedback loop. Disconnecting your amplifier's signal input leads or selecting an unused input is usually good enough to check whether this is how the noise enters the system. Using very short speaker leads is another way to check this but probably inconvenient.
In quite a few cases, I've found periodic popping and crackling noise was actually caused by the solenoid power switches in freezers, refrigerators, air conditioners, stoves and other heavy current appliances in the home, which are often cycling on/off continuously . The contacts become damaged and they tend get noisier, emitting an increasing spray of EMI energy as they age, so YMMV.
Could the brownout have fried the caps in the EMC filter and now it is picking up your fridge? Can you try it in another building, relative’s/friend’s etc. to rule out something in your place interfering with it?
Brian
Brian
Thanks, everyone, for your input. I reproduced the problem in my office, but I'm not 100% it's the same pop, since in my office, static discharged when I operated the volume knob on my preamp. To keep track, I made this spreadsheet on Google Docs.
I heard the pop from the left speaker, but I've also heard it come from the right.
Friends at AK suggested it might be noisy transistors?
@brig001 -- It has been with two seasoned technicians since the problem started; maybe they didn't hear the pop, or something else explains the issue.
I heard the pop from the left speaker, but I've also heard it come from the right.
Friends at AK suggested it might be noisy transistors?
@brig001 -- It has been with two seasoned technicians since the problem started; maybe they didn't hear the pop, or something else explains the issue.
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You know you have a real noise problem, when a spreadsheet is needed to keep track of it.
It could be noisy transistors, but unlikely to be heard simultaneously in both channels if that’s the problem. Make notes of DC offset at amp output—- abrupt shifts might be clues. I’d test with no signal applied. Monitor with a scope avaliable.
Good luck!
It's maddening.
@BSST -- Thanks for the tip. Unfortunately, I'm a total novice enthusiast. It was given a clean bill of health by Jon Soderberg of Vintage Amp Repair, and no lingering issues were noted.
Hi avantbored,
I was authorized warranty for Nakamichi and on these series of audio components.
I have a good idea what is going on and have seen it before (and solved it). There are a number of things that should be done at this age. Too bad you're far away, it really isn't a DIY job and the equipment is rather too good for that.
See if you can get it to a good audio service shop that was warranty for the PA-7 and PA-7II. These do not need "upgrades", they were designed very well and used very good component types. I know because I have been asked to upgrade them and examined them from that viewpoint.
-Chris
I was authorized warranty for Nakamichi and on these series of audio components.
I have a good idea what is going on and have seen it before (and solved it). There are a number of things that should be done at this age. Too bad you're far away, it really isn't a DIY job and the equipment is rather too good for that.
See if you can get it to a good audio service shop that was warranty for the PA-7 and PA-7II. These do not need "upgrades", they were designed very well and used very good component types. I know because I have been asked to upgrade them and examined them from that viewpoint.
-Chris
The more difficult the problem, the more important it is to use a scientific approach.
First step would be to definitely localize the problem to one and only one of the audio components.
The same problem happening in two different components in the system would be very unlikely.
The problem here is that you must take the channel PCBs off (both), and disconnect or remove all the output transistors. Outputs have a mounting torque, so you need a torque screwdriver for that. Fresh insulators and grease if you go mica. The bias transistors are on another PCB and the cable can go intermittent.
There are replacements needed for some transistors, matching compliments helps. Some areas of the PCB ran hot, so to avoid damage takes some skill. This is not a job for someone starting out, or a tech not very accustomed to working on equipment like this. It takes patience.
These are very good amplifiers. I am tired of seeing them damaged due to poor service techniques. To lose this amp for the sake of getting it done cheaply is just very sad.
-Chris
There are replacements needed for some transistors, matching compliments helps. Some areas of the PCB ran hot, so to avoid damage takes some skill. This is not a job for someone starting out, or a tech not very accustomed to working on equipment like this. It takes patience.
These are very good amplifiers. I am tired of seeing them damaged due to poor service techniques. To lose this amp for the sake of getting it done cheaply is just very sad.
-Chris
That would certainly be useful for both troubleshooting, and for dealing with the problem.
I use these, and have at least one in each room. They also make 8 outlet power strips.
https://www.amazon.com/Tripp-Lite-Protector-Right-Angle-ISOBAR6ULTRA/dp/B0000513US
I use these, and have at least one in each room. They also make 8 outlet power strips.
https://www.amazon.com/Tripp-Lite-Protector-Right-Angle-ISOBAR6ULTRA/dp/B0000513US
