Nearing wit's end troubleshooting NAD T777 v3 AVR

[keeney123]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

I suppose you did a factory reset and checked that the FW is up to date? I think that's pretty much all you can do. I don't think the problem is in the analog part, it has to be on the digital side. You could look at the block diagram in the service manual, and probably find a few IC's that you could try to replace. If you sending it back, NAD probably is just replacing boards.

Have these Manufacturers stop repairing down to component level? If so, that is pretty sad as they will never know what is going wrong with their units.

[keeney123]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

Fytonv if you decide to take the unit to NAD first ask them if they troubleshoot the units down to component level. Then post what they said here.

[CapLeaker]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

Not going to happen, as the cost of doing so would exceed the value of the unit. So they just put a new board in, maybe do an alignment, call it quits and charge you an astronomical repair bill.

[keeney123]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

Not going to happen, as the cost of doing so would exceed the value of the unit. So they just put a new board in, maybe do an alignment, call it quits and charge you an astronomical repair bill.

Unbelievable. No wonder there is so much junk on the market. If something is wrong with the design, they will never know it because they just will keep replacing boards.

[CapLeaker]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

Unfortunately that’s the name of the game these days. There is hardly anyone that does component level repair now. After all companies are out for profits and minimize expenses. There are much bigger companies than NAD, that won’t even do a firmware update to get rid of a bug, but yet charge $3500 new to buy. What gives?!

[keeney123]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

Unfortunately that's the name of the game these days. There is hardly anyone that does component level repair now. After all companies are out for profits and minimize expenses. There are much bigger companies than NAD, that won't even do a firmware update to get rid of a bug, but yet charge $3500 new to buy. What gives?!

Simple want to collect a paycheck without doing work.

[fytonv]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

Just to partially close the loop here, CapLeakers statements on repair approaches are true. After digging around, it seems near impossible to find a repair shop that's going to actually fix the hardware inside the unit. NAD farms out repair work to authorized service centers. There are 2 of those within a couple of hours from my place.

Repair place #1, which happens to be pretty close by, said: "no thank you, I'm too busy. call someone else."

Repair place #2 said: "Sure, we can fix it. it may take around a month to 6 weeks, depending on parts availability from NAD".

It feels inevitable that it'll cost more $$ to repair than it's actually worth. I'm taking that money and getting a new AVR, something with a 3 year warranty. Since the NAD still mostly works, I'll keep it as a spare. When the new AVR fails I'll bring the NAD out of cold storage .

I'm sorry that we'll probably never know what's wrong with this thing.

[keeney123]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

Just to partially close the loop here, CapLeakers statements on repair approaches are true. After digging around, it seems near impossible to find a repair shop that's going to actually fix the hardware inside the unit. NAD farms out repair work to authorized service centers. There are 2 of those within a couple of hours from my place.

Repair place #1, which happens to be pretty close by, said: "no thank you, I'm too busy. call someone else."

Repair place #2 said: "Sure, we can fix it. it may take around a month to 6 weeks, depending on parts availability from NAD".

It feels inevitable that it'll cost more $$ to repair than it's actually worth. I'm taking that money and getting a new AVR, something with a 3 year warranty. Since the NAD still mostly works, I'll keep it as a spare. When the new AVR fails I'll bring the NAD out of cold storage .

I'm sorry that we'll probably never know what's wrong with this thing.

Before you go and buy the New AVR with the 3-year warranty. Read the warranty and all the ways they can escape the warranty. Make sure you buy from an authorized dealer otherwise the warranty will not be worth 2 cents. Or just buy the cheapest AVR with no warranty and gamble it is going to be good. Either way it is a gamble just depends on how much money you will want to pay for that gamble.

[budwich]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

I've tested cables, sources, and inputs ad nauseam. My normal setup has an Apple TV 4K, Nvidia Shield Pro, and a PS5 all connected to the NAD via HDMI, and the NAD outputs HDMI to a Samsung display. I don't use ARC. The problem happens on both the Apple TV and Shield. It even happens when the Apple TV is connected directly to the display while passing audio back to the NAD via an optical connection. Swapped speakers, too.

I'll check out that AV forums site. I've done a tone of googling on problems with this AVR, but haven't stopped there yet.

Appreciate the help!

IF you want to try do some more "testing", you might try doing different audio settings output from the boxes in question. I don't believe that you have actually indicated what they are set at. Not sure what the choices are, but try something like PCM versus bitstream, etc. to see if that changes anything. That might help indicate whether it is a decoder problem, or maybe D/A problem. Just a thought. As you have postulated, trying to get a repair done by a center is likely not economical so "playing around" some more is your "time cost" with little to risk, but you never know what you may find.

[keeney123]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

I have not been an active technician in the field for several years. With that said in order to troubleshoot a problem that the company is not willing to do to component level you would need to have the schematics, software programs and a Oscilloscope that is capable of matching the frequencies of the equipment use. For the logic side of the equipment, you would need a logic analyzer capable specification wise of capturing the voltage and frequency levels of that equipment. If a design problem, comes up you would have to understand by reading the program printout where the problem occurred in the hardware. For instance, a piece of equipment I worked on had a noise glitch between data pulses. The Software Engineer who also had an electrical background was able to read the printout of the program and locate the problem on the hardware. Even though he was able to locate this problem he could not change the problem because of the constraints of the electronic ICs. This was done when pushing the piece of equipment to its limit trying to get the most out of the equipment. This was in 1986 and the noise pulse was 27ns wide at its base, I forgot what the voltage was. I do not suggest that the AVR companies are trying to push the electronics ICs to their limits but, I am saying in order for a person to be able to troubleshoot a problem that could be a design problem to component level one needs a lot of information and equipment and know how. If the Manufacturer is unwilling to do this than I believe you will be at a loss. Other than blindly replacing parts and programs.

[fytonv]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

Interesting. Good idea as I hadn't tested with different source audio formats. And it turns out this problem only occurs when the source format is PCM! Well, at least that's what I'm experiencing at this moment. It's a buggy device though so time will tell.

All things considered, I have figured out a way to solve this issue permanently. I'm working on repositioning the NAD's power cord. It's a delicate electrical procedure that involves taking the power cord out of the NAD and permanently connecting it to another receiver. I'm pretty sure that'll fix the problem.

Good call on testing signal processing. This will hopefully lower the nuisance level until I upgrade.

IF you want to try do some more "testing", you might try doing different audio settings output from the boxes in question. I don't believe that you have actually indicated what they are set at. Not sure what the choices are, but try something like PCM versus bitstream, etc. to see if that changes anything. That might help indicate whether it is a decoder problem, or maybe D/A problem. Just a thought. As you have postulated, trying to get a repair done by a center is likely not economical so "playing around" some more is your "time cost" with little to risk, but you never know what you may find.

[keeney123]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

Interesting. Good idea as I hadn't tested with different source audio formats. And it turns out this problem only occurs when the source format is PCM! Well, at least that's what I'm experiencing at this moment. It's a buggy device though so time will tell.

All things considered, I have figured out a way to solve this issue permanently. I'm working on repositioning the NAD's power cord. It's a delicate electrical procedure that involves taking the power cord out of the NAD and permanently connecting it to another receiver. I'm pretty sure that'll fix the problem.

Good call on testing signal processing. This will hopefully lower the nuisance level until I upgrade.

Are you saying that the AC electrical magnetic interference is causing your problem?

[fytonv]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

Sorry. It was 100% sarcasm. The ideal repair for the NAD is recycling and replacing it with a different AVR.

[budwich]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

Interesting. Good idea as I hadn't tested with different source audio formats. And it turns out this problem only occurs when the source format is PCM! Well, at least that's what I'm experiencing at this moment. It's a buggy device though so time will tell.

All things considered, I have figured out a way to solve this issue permanently. I'm working on repositioning the NAD's power cord. It's a delicate electrical procedure that involves taking the power cord out of the NAD and permanently connecting it to another receiver. I'm pretty sure that'll fix the problem.

Good call on testing signal processing. This will hopefully lower the nuisance level until I upgrade.

Ah... but now you are taking a different signal path thru the processor board. Again, it depends on how much time you want to spend on things (learning or otherwise)... along with finding some form of schematic which can be trying, but some are usually around. Anyway, it sounds like you have decided on a "work around" / replacement procedure...:-) no problem.

[fytonv]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

I’m interested in plugging away at this, but still replacing it though. I found a service manual for a 758, which is a different model in the same line up. The module schematics appear very similar. Curiosity will drive me to do more studying tonight.

[keeney123]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

Sorry. It was 100% sarcasm. The ideal repair for the NAD is recycling and replacing it with a different AVR.

Thanks for the explanation. If you get to frustrated with it, you could always have a bulldozer run over it on a concrete pavement.

[budwich]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

I’m interested in plugging away at this, but still replacing it though. I found a service manual for a 758, which is a different model in the same line up. The module schematics appear very similar. Curiosity will drive me to do more studying tonight.

this is one for the unit. Another question about your first post... you indicate that there was an issue with caps in the psu or you found a post about that problem?

[fytonv]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

Wow. Thanks for that manual! I deleted the manual I was using a few days ago. I searched the Internet for a couple of hours last night and I couldn't find a copy.

Regarding your question... I'm unsure this is related. There was a different problem (probably different problem) that started me down this path of a DIY repair. This NAD experienced frequent audio drops and some light distortion/crackling on the speaker channels supported by the right side amplifier. There are 2 amp modules, right at left. The left supports all the "left channels" and the right supports all the "right" channels + the center. Each channel passes through its own speaker relay. All of the speakers supported by that right amp module would intermittently have audio issues.

I tore the whole unit apart to look for shorts and tested paths with a multimeter in a rudimentary way, looking for continuity where continuity should exist. I don't own or know how to use an oscilloscope, but I'm thinking about remedying that to learn a bit more. Anyway, in my mind this initial problem was a power supply issue, but someone on the forum mentioned it was probably the speaker relays and that I should try cranking up the volume when the problem occurs. I put the whole thing back together and did just that, and the problem hasn't happened since. I still get a bit of crackle now and then, so this problem likely isn't 100% resolved. Also, these two symptoms overlap in an interesting way. Anyway, the speaker relay issue may be a red herring. I agree that the symptoms would closely resemble a problem with the speaker relay, but there are 5 identical relays on that right amp module. All of them failing in the same way around the same time seems unlikely. And this receiver is only a few year old.

[keeney123]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

It will not take you long to learn how to operate and Oscilloscope. It basically is only voltage amplitude and frequency/time. Of course, when you advance there are X-Y modes and different trigger inputs. But the basic operation is simple along with the graph on the screen one reads. Calibration of the probes is also very simple with the square wave available, and the potentiometer adjust. This will open your view and understanding of what is going on in a circuit.

When the frequency of computers started to outpace the capabilities of the Oscilloscopes, they started relying on logic analyzers for that information. I suppose they must today have logic analyzers that are capable of capturing or recording the complete signal and then reproducing it on a screen such as a display like the Oscilloscope.

The later I would base on because of the ring counters they use in 1980-1981 to capture events off of drift chambers in High Energy Physic experiments at Brookhaven and storing that information in Nevis Crates then loading that information on reel-to-reel tapes for later analysis. The whole experiment was only as good as the front end of the experiment. The front end had specialized filters and electronics, so the signals were captured, and noise was eliminated off the wires of the drift chambers.

I think it would be worth it for you to lean the Oscilloscope. It would not require much effort and if you had an instructor to show you how, you could learn the basics in a matter of hours with a good comprehension.

For a more complete understanding you could study what actually is happening in the Oscilloscope, electronic and beam wise that causes it to be reproduced on the screen the way it does. This was the forerunner of the CRT= Cathode Ray tubes TV Screens.

[budwich]

Re: Nearing wit's end troubleshooting NAD T777 v3 AVR

Wow. Thanks for that manual! I deleted the manual I was using a few days ago. I searched the Internet for a couple of hours last night and I couldn't find a copy.

Regarding your question... I'm unsure this is related. There was a different problem (probably different problem) that started me down this path of a DIY repair. This NAD experienced frequent audio drops and some light distortion/crackling on the speaker channels supported by the right side amplifier. There are 2 amp modules, right at left. The left supports all the "left channels" and the right supports all the "right" channels + the center. Each channel passes through its own speaker relay. All of the speakers supported by that right amp module would intermittently have audio issues.

I tore the whole unit apart to look for shorts and tested paths with a multimeter in a rudimentary way, looking for continuity where continuity should exist. I don't own or know how to use an oscilloscope, but I'm thinking about remedying that to learn a bit more. Anyway, in my mind this initial problem was a power supply issue, but someone on the forum mentioned it was probably the speaker relays and that I should try cranking up the volume when the problem occurs. I put the whole thing back together and did just that, and the problem hasn't happened since. I still get a bit of crackle now and then, so this problem likely isn't 100% resolved. Also, these two symptoms overlap in an interesting way. Anyway, the speaker relay issue may be a red herring. I agree that the symptoms would closely resemble a problem with the speaker relay, but there are 5 identical relays on that right amp module. All of them failing in the same way around the same time seems unlikely. And this receiver is only a few year old.

Ok... thanks for the further info. Not sure what else to say at this point without you doing some further testing / checks.

The service manual has some checks here and there BUT most rely on scope traces. The problem with doing solely ddm checks, is that you can't see how "clean" things are in terms of powering and signalling or otherwise.

To me the NAD unit is worth the investment... time and money wise... but that is just my opinion. Anyway, as suggested by others, a scope would be handy. Like most things these days, technology has made things easier and cheaper for the "average individual" to get access to AND use with little to no training as "good help" can be readily found on the internet in both forums and otherwise.

Personally, I have an old two channel crt scope BUT picked up a handheld scope for less than $100 (off shore brand of course). The handheld can readily be used by most... as it has "auto functions", etc that basically, you hook up and press a button and "bob's your uncle" there after.

The good thing about hand held scopes that are battery powered, much like DDM's you don't really have to worry about where your reference points are for your probes as opposed to line powered scopes which don't like you putting your probe's reference (usually ground internally) just anywhere in a circuit... :-)

Anyway, again its things that you have to weigh for your own sake.

I would say that although you have tried a "bunch of configuration / cable" changes, I think you need to do a few more to simplify what the problem is to narrow done which part of the circuit comes into play.... further for instance, only two channel input, pcm, speaker setup: 2,5.1, etc.

Having said that, there is still a high possibility that there is a component level problem in one of the chips on the main board which may be not be easily addressed because of both availability and repair technique (ie. large form factor, pin count).