Jump to content

Sign in to follow this  
Green Wagon

NAD 7020 Receiver - 16-6-15 Now with more 7020 - Two of them :)

Recommended Posts

EDIT 16-6-2015 - Second later revision added further down - post #26...

 

I make no secret of it.

I'm not a fan of NAD.

So many different revisions of the same model number.

This one is the earlier version. 

Later versions (from what I see in service manuals) look to be designed by someone with a better sense of layout and serviceability

 

Recap and fix intermittent loss of one channel.

 

post-106429-0-72352100-1433598117_thumb.

 

Any Pastafarians here will love this delicious serving of spaghetti. All Hail the great FSM  :welcome:

Did someone forget to connect something ?

 

post-106429-0-73452000-1433598145_thumb.

 

Mmmmm. Guess most were using basic power switching transistors for their amplifiers in the 70's.. (ETI / EA anyone)

 

post-106429-0-33800900-1433598161_thumb.

 

NAD are not alone in using this damn 'Gorilla snot' glue.

I just love the way it eats through tracks.

Bonus points for it being hidden under the capacitor..

 

post-106429-0-24098800-1433598174_thumb.

 

But the cure is simple. Find the breaks in the tracks. Either bridge it or in this case for long term reliability just bypass the whole section of track.

One saving grace of this unit is the ability to remove top and bottom covers to allow work without having to remove every last screw before taking the board out.

Yes yes, its filthy. Had only just put in the freeway, I mean bypass, and I hadn't verified the fix before cleaning it.

 

post-106429-0-24855200-1433598203_thumb.

 

Yeah that cap is well past its use by date...

 

post-106429-0-53737300-1433598215_thumb.

 

I stopped counting at 70 of the things.

Some were a real joy to get at to replace...

Quite a decent number of them were ready to vomit......

 

post-106429-0-28837100-1433598347_thumb.

Edited by Green Wagon

Share this post


Link to post
Share on other sites

If you think the wiring is bad, you should see some of the European gear I work on, I had to confirmed a open circuit on Friday that took me all day to pull apart and bypassed safely a wire that became open on the inside of the insulation. We are now judged on the time we spent on the call that is calculated at $80/hr! Those f]#]<%g accountants with there creative accounting methods! because it's all on a maintenance contracts. At least the wiring here is still colour coded. The Japanese gear that this European gear it interface with are all using light gauge grey wiring! For everything! And because steel is now at a premium the gauge and strength of metal chassis are now paper thin, you look at these devices and they bend! What is so disappointing about European/American Equipment is that once you pull something apart it has to be readjusted to work, and I'm not having any joy in getting it to work, a job for Tuesday, knowing very well that I have to Order a retrofit wiring kit that's now going to cost the company $500-600 and 3 days work involving 2 of us. When people say to me that the Europeans and American gear make decent and better gear than the Asians, I look at them and smile and wished they seen some of the gear I work on!

Edited by Addicted to music

Share this post


Link to post
Share on other sites

I stopped counting at 70 of the things.    Some were a real joy to get at to replace.    Quite a decent number of them were ready to vomit......

 

attachicon.gifcaps.jpg

Green Wagon, what caps did you replace these caps with?

Edited by Ping

Share this post


Link to post
Share on other sites

If you think the wiring is bad, you should see some of the European gear I work on, I had to confirmed a open circuit on Friday that took me all day to pull apart and bypassed safely a wire that became open on the inside of the insulation. We are now judged on the time we spent on the call that is calculated at $80/hr! Those f]#]<%g accountants with there creative accounting methods! because it's all on a maintenance contracts. At least the wiring here is still colour coded. The Japanese gear that this European gear it interface with are all using light gauge grey wiring! For everything! And because steel is now at a premium the gauge and strength of metal chassis are now paper thin, you look at these devices and they bend! What is so disappointing about European/American Equipment is that once you pull something apart it has to be readjusted to work, and I'm not having any joy in getting it to work, a job for Tuesday, knowing very well that I have to Order a retrofit wiring kit that's now going to cost the company $500-600 and 3 days work involving 2 of us. When people say to me that the Europeans and American gear make decent and better gear than the Asians, I look at them and smile and wished they seen some of the gear I work!

 

EDIT > Yes it took me a couple of hours to find that track. Isolate (by removing components) preceding low level signal stage, test, ok one end, dc other end. 

Experience with what gorilla snot can do helped point me to look under caps and scrape of solder mask to find . . . . . . missing copper.

 

No, It's not the worst, not by a loooong shot.

Early aiwa, nakamichi, and particularly any early and cheap receivers or tape decks are not much better.

The nakamichi st7 tuner, I've done maybe half a dozen of those, and every single one has been very different internally.

Some of the early car audio stuff...... Words cannot describe it. It's like someones just taken the casework and decided to see how much wire they can shove in their.

Don't get me started on trucks, taxi's, english and french cars.

God just the thought of the french cars I've worked on gives me shivers.... Could fill a page with their stupidity. Citroen, battery and motor up front, main cable run underneath to the back, before being run BACK to the front  :confused: .

Volvo trucks on the other hand, they should be used as examples on how to wire vehicles.

Undo two twist locks on the cabins internal tray, lift it out, and there is everything, beautifully laid out, labeled and fused.

Not one other truck or car I've worked on comes close.

 

 

 

Green Wagon, what caps did you replace these caps with?

 

 

 

Normally I prefer to use the EXR range from WES.

Decent range of values and voltages, 105deg, low ESR.

I know some do not like them, but after many years I haven't had a single issue with them.

Majority of customers inform me afterwards that their >Insert device here< has never sounded so good afterwards.

Although I think thats more a matter of fresh better made caps and the re-solder I end up doing on most gear.

Lets face it, fresh is almost always better than stale and perished no matter what your talking about....  :ph34r:

Edited by Green Wagon

Share this post


Link to post
Share on other sites


Green Wagon, what do you find is the best way to remove the Gorilla snot without affecting the copper tracks and to prevent any further deterioration... thanks :)

Share this post


Link to post
Share on other sites

There wasn't a lot of 105 +C caps available back then like there is today. If you can get the 105 C back then it was always small values.

The next generation of pcbs are full of LSI that you can't get to the pins. A whole new desoldering techniques are required. Just lucky that the stuff up to the early 80s are still through the hole components. Unfortunately HiFi manufacturers have no say and is dictated as passive components and its SS cousins are moving into the world of miniaturisation and SMD as a cost saving in production. We don't even go to board level repair, it's cheaper to order one and replace it but it's then destined for landfill. Most class D modules are exactly that, if it fails it's landfill! It makes it harder to DIY also, and as you age like I have, it's harder to see and handle the minturisation of SMD.

Share this post


Link to post
Share on other sites

Green Wagon, since you have gone to the trouble of replacing all those caps are also going to replace the steel RCA sockets  with decent sockets and replace the speaker wire clips with decent 5way Binding Posts :)

Share this post


Link to post
Share on other sites

Green Wagon, since you have gone to the trouble of replacing all those caps are also going to replace the steel RCA sockets  with decent sockets and replace the speaker wire clips with decent 5way Binding Posts :)

 

I guess it depends why they need to be changed. If it's for the sake of practicality, or to replace damaged components... it might be worth doing. On the other hand, if it's for any perceived sonic benefits, it's not worth the hassle on this type of equipment. The RCAs/binding posts certainly aren't hobbling the sound in any way.

Edited by pete_mac

Share this post


Link to post
Share on other sites


Haha i remember a client requesting I install $130 WBT posts on a cheap T amp that he didn`t want thrown away. Was funny.

Share this post


Link to post
Share on other sites

In my experience older NAD gear = dry joints, damage to PCB's due to inadequate thermal design, and dead caps also due to inadequate thermal design.

Share this post


Link to post
Share on other sites

... On the other hand, if it's for any perceived sonic benefits, it's not worth the hassle on this type of equipment. The RCAs/binding posts certainly aren't hobbling the sound in any way.

maybe, then why bother with the caps, etc ...

 

Green Wagon, would you agree with this :)

Share this post


Link to post
Share on other sites

maybe, then why bother with the caps, etc ...

 

Green Wagon, would you agree with this :)

Why bother? Well, let's explore the improvements yielded via recapping vs replacing RCA sockets and binding posts.

Capacitors have a finite lifespan and their performance deteriorates over time (as does the performance of the amp). Moreover, old capacitors can lead to other components failing (collateral damage). Changing capacitors on older gear provides tangible sonic and reliability benefits and ensures the performance of the amp is as the designer intended it. This is why it we do it.

On the other hand, throwing fancy binding posts and RCA sockets on an older amp will have absolutely minimal impact upon the sound. If they are defective, sure, replace them... but don't expect a fundamental improvement in the sound of the amp.

In short, the benefits of recapping an older, worn amp are many orders of magnitude greater than can be achieved by fitting fancy binding posts and RCA sockets.

For the sake of clarity, I'm coming at this from the perspective of someone who has restored many, many amps, and installed different binding posts (mainly from a practicality perspective) and RCA sockets from time to time. I've used pure copper CMC binding posts on my own amps, and like Eichmann, KLE and Aurealis/Star RCA connectors due to the purity of materials. I believe it makes a difference. But... Nowhere near as much of a difference as recapping an amp, and certainly not enough to overcapitalise upon a relatively cheap amp.

Share this post


Link to post
Share on other sites


Green Wagon, perhaps this post should have said ..."since you have gone to the trouble of replacing all those caps are also going to replace the steel RCA sockets with decent $1 or $2 copper based sockets and replace the speaker wire clips with decent Chinese 5way Binding Posts that are just a few dollars each" :)

Share this post


Link to post
Share on other sites

Green Wagon, perhaps this post should have said ..."since you have gone to the trouble of replacing all those caps are also going to replace the steel RCA sockets with decent $1 or $2 copper based sockets and replace the speaker wire clips with decent Chinese 5way Binding Posts that are just a few dollars each" :)

That's better ;) hehe

Re: $1-2 copper based sockets, if you find any that are in fact copper, please let me know! All of the moderately-priced Chinese stuff which masquerades as copper is brass or 'high copper alloy' (same/same). I've bought, I've tested, I've frowned :(

Edit: and when I say 'frowned', from the perspective of not being 'copper' rather than any other judgement regarding their build quality. Only a few RCA sockets are actually tellurium or beryllium copper based upon my findings.

Edited by pete_mac

Share this post


Link to post
Share on other sites

Green Wagon, what do you find is the best way to remove the Gorilla snot without affecting the copper tracks and to prevent any further deterioration... thanks :)

 

Throw the item out. 

Once the chemical damage is done there are only two ways to fix it. Throw it out or repair it.

As this glue ages it leaches through the solder mask and attacks the copper. Once the copper is gone it isn't coming back.

Only way to fix it is to scrape it back to the board and do whatever repairs are needed.

 

There wasn't a lot of 105 +C caps available back then like there is today. If you can get the 105 C back then it was always small values.

The next generation of pcbs are full of LSI that you can't get to the pins. A whole new desoldering techniques are required. Just lucky that the stuff up to the early 80s are still through the hole components. Unfortunately HiFi manufacturers have no say and is dictated as passive components and its SS cousins are moving into the world of miniaturisation and SMD as a cost saving in production. We don't even go to board level repair, it's cheaper to order one and replace it but it's then destined for landfill. Most class D modules are exactly that, if it fails it's landfill! It makes it harder to DIY also, and as you age like I have, it's harder to see and handle the minturisation of SMD.

 

Yup. Even if people have the tech and training to replace vlsi chips, the chips themselves either aren't available or cost so much that it becomes a "not viable to repair".

I tried repairing a class D from a marten logan not long ago. zero information, part codings that could be one of 7 different devices. Throw it away for the sake of $15 in smd parts. Great going B&O. (Ice power)

 

Green Wagon, since you have gone to the trouble of replacing all those caps are also going to replace the steel RCA sockets  with decent sockets and replace the speaker wire clips with decent 5way Binding Posts :)

 

Because its a NAD.

Attempting to replace the rca sockets would be a world of pain and bs that just isn't worth it.

Also wasn't requested and even it was I would've advised against it.

 

Putting lingerie on a pig destined for bacon sandwich's springs to mind.

 

Mmmmmmm Bacon *** Droools ***

 

I guess it depends why they need to be changed. If it's for the sake of practicality, or to replace damaged components... it might be worth doing. On the other hand, if it's for any perceived sonic benefits, it's not worth the hassle on this type of equipment. The RCAs/binding posts certainly aren't hobbling the sound in any way.

 

BINGO, We have a winner.

Repairs and making it sound good are two totally different things for some gear.

 

Haha i remember a client requesting I install $130 WBT posts on a cheap T amp that he didn`t want thrown away. Was funny.

 

LOL.

Yeah we all get those don't we.........

 

In my experience older NAD gear = dry joints, damage to PCB's due to inadequate thermal design, and dead caps also due to inadequate thermal design.

 

Yup. lotsa dry joints. I love the way they raise components because they just can't physically make them fit any other way.

 

maybe, then why bother with the caps, etc ...

 

Green Wagon, would you agree with this :)

 

Not everyone can afford a new car just because one tyre is flat.

Surely you have something that has sentimental value that you would rather repair than throw out.

 

 

Why bother? Well, let's explore the improvements yielded via recapping vs replacing RCA sockets and binding posts.

Capacitors have a finite lifespan and their performance deteriorates over time (as does the performance of the amp). Moreover, old capacitors can lead to other components failing (collateral damage). Changing capacitors on older gear provides tangible sonic and reliability benefits and ensures the performance of the amp is as the designer intended it. This is why it we do it.

On the other hand, throwing fancy binding posts and RCA sockets on an older amp will have absolutely minimal impact upon the sound. If they are defective, sure, replace them... but don't expect a fundamental improvement in the sound of the amp.

In short, the benefits of recapping an older, worn amp are many orders of magnitude greater than can be achieved by fitting fancy binding posts and RCA sockets.

For the sake of clarity, I'm coming at this from the perspective of someone who has restored many, many amps, and installed different binding posts (mainly from a practicality perspective) and RCA sockets from time to time. I've used pure copper CMC binding posts on my own amps, and like Eichmann, KLE and Aurealis/Star RCA connectors due to the purity of materials. I believe it makes a difference. But... Nowhere near as much of a difference as recapping an amp, and certainly not enough to overcapitalise upon a relatively cheap amp.

 

Yup, What he said :D

 

There are other amplifiers that use these same 3055/2955 transistor pair for outputs.

They were never designed for audio. They are no more than cheap power switching transistors.

Yet a lot of places used them, because they were cheap, reliable, and so damn easy to design around.

Look at the ETI 480 modules. Gotta be 40 years old now. still in use today.

Take Quad. They also used to use common cheap easy to get parts. Why. Because of just that.

Post war metals were hard to find and expensive. Why use things you probably couldn't get next week.

That means a redesign. Lost time, lost profits.

Edited by Green Wagon

Share this post


Link to post
Share on other sites

Green Wagon, perhaps this post should have said ..."since you have gone to the trouble of replacing all those caps are also going to replace the steel RCA sockets with decent $1 or $2 copper based sockets and replace the speaker wire clips with decent Chinese 5way Binding Posts that are just a few dollars each" :)

 

 

Sure, go for it. :)

Go out and buy a similar vintage japanese unit.

And see how you go replacing the rca connectors.

 

I'd rather perform a lobotomy on myself with a hilti hammer drill.

 

It just is not worth the hours of pain trying to get them to fit.

Edited by Green Wagon

Share this post


Link to post
Share on other sites


Normally I prefer to use the EXR range from WES.

Beware of WES electros. I won't touch ANY WES electros ever again. Out of a bag of 100 EXR types I recieved, more than 25 were faulty! Unfortunately, a few ended up in customer's products before I knew what was going on. After finding that the caps were potentially faulty, I then had to issue my own recall, so I could replace the suspect caps. WES refunded my purchase price (big whoop - about $100.00), but the labour costs blew any profitability out of the water.

I ONLY use Panasonics, or quality caps from other ISO traceable manufacturers now. The cost is roughly double, but well worth it. Myabe WES have sorted out their problems with their electros, but I don't care. They'll lost that part of my business forever.

I sleep much more soundly.

Edited by Zaphod Beeblebrox

Share this post


Link to post
Share on other sites

1% would be pretty bad.

But 25%, thats bordering on criminal to me.

 

Can you say how long ago and what sort of failure ?

 

Maybe they've fixed the supplier, or maybe I've just been dodging bullets........

Share this post


Link to post
Share on other sites

Ya gotta thank ZB in letting you know.

Share this post


Link to post
Share on other sites

Well that goes without saying. but thanks for remind me.

 

Thank you ZB. * Bows graciously *

Share this post


Link to post
Share on other sites

Well that goes without saying. but thanks for remind me.

 

Thank you ZB. * Bows graciously *

 

:thumb:    God I love this SNA community! :)

Share this post


Link to post
Share on other sites

Speaking of NAD, I had a look at a few NAD cd players from the 90's that I still have awaiting for replacement parts when they do pop up, essentially every NAD that ever had brown or the old style blue coloured PCB's have:

 

1. Brown glue gunk next to electrolytics.

2. Dry solder joint issues.

3. Very generic capacitors.

4. Flux all over solder joints that are not cleaned up.

Share this post


Link to post
Share on other sites

1% would be pretty bad.

But 25%, thats bordering on criminal to me.

 

Can you say how long ago and what sort of failure ?

 

Maybe they've fixed the supplier, or maybe I've just been dodging bullets........

It is disgusting. The caps leaked. In fact, what alerted me to the problem was that some leaked BEFORE installation. I suspect a faulty seal. It was roughly 3 ~ 4 years ago. The Panasonic FC series have never let me down. It is probable that the WES caps I was supplied were a bad batch (that was what WES told me), but, as a professional, I cannot afford such mistakes from my suppliers.

Share this post


Link to post
Share on other sites

Speaking of NAD, I had a look at a few NAD cd players from the 90's that I still have awaiting for replacement parts when they do pop up, essentially every NAD that ever had brown or the old style blue coloured PCB's have:

 

1. Brown glue gunk next to electrolytics.

2. Dry solder joint issues.

3. Very generic capacitors.

4. Flux all over solder joints that are not cleaned up.

 

Yes.

I did say nad wasn't my favorite brand.

Once did a pair of their mono blocks.

Board was supported solely by the outputs at either side.

Not one stand off that I can remember.

 

Mind you, those faults can be attributed to ALMOST all manufacturers..

 

 

It is disgusting. The caps leaked. In fact, what alerted me to the problem was that some leaked BEFORE installation. I suspect a faulty seal. It was roughly 3 ~ 4 years ago. The Panasonic FC series have never let me down. It is probable that the WES caps I was supplied were a bad batch (that was what WES told me), but, as a professional, I cannot afford such mistakes from my suppliers.

 

Thanks ZB.

 

Ahh ok, 3-4 years ago I was 'employed', tearing the poo out of my arm tendons.

It's only the last year or two that I've gotten back into the repair side.

 

That really is disgusting.

I'd wonder if they weren't an old stock clean out.

I'm pretty sure all their lines are hand 'picked/packed' so it might have been possible to be spotted by the picker.

If they were conscientious enough........

Then again, I've done my share of rapid busy picking from overcrowded, dimly lit, dusty storage areas and shelves.

I know when I pick a customers order I make sure every part is as ordered and then tick it of as it gets packed.

So far. . . . . I haven't made a mistake.

But there is always tomorrow  :ph34r:

Edited by Green Wagon

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

  • Classifieds Statistics


    Currently Active Ads

    Total Sales (Since 2018)

    Total Sales Value (Last 14 Days)

    Total Ads Value (Since March 2020)
  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...