NAD 3020 Vintage Amplifier Repair & Service

I was asked to repair this NAD 3020i Amplifier from 1998.
I also gave it a service.
It didn't go exactly to plan, but we got there in the end.
The NAD 3020 was the most popular amplifier in the world at one point.
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Check out my Watchmaking channel: ‪@watchout9213‬

[@poormanselectronicsbench2021]

If you have any older, larger value and voltage( 5KuF and 50WV ) or more electrolytic caps, you can put one in line with each test speaker to prevent damage to them. Some older transistor amps had them in the amp's design ( Dynaco ST-120 for example) It'll save some speaker smoke if things go south while testing in the future. Good effort nonetheless! 👍

[@audionautica6843]

That's a simple but fantastic suggestion - thanks for that! Of course the NAD 3020 / 3120 has no speaker protection circuit at all, so yes, if something goes wrong it can end in smoke. The Leak Stereo 70 is another amplifier that has series caps in the output.

[@mikevincent6332]

Good idea, never thought of it before - you'd want 2 of them back to back though to make it bipolar

[@viktor928]

@@audionautica6843 I think my NAD 3020 series20 cost me the twitter to burnout on my Infiniti Alpha 50… Towers. Currently left channel is pretty scratchy, on the mid range, start button make that scratchy sound when turn on for 5/seconds…😭😭😭 …now its off my system using the 3020D …hybrid, that I don’t really like…got the NAD 2200 & 1155 coming soon… if you can’t help with my 3020 series 20 will be fantastic I can make video and describe the problem and pay you whatever you think it’s reasonable.

[@audionautica6843]

@@viktor928 It really needs to be on a bench to repair and sounds like parts will definitely need replacing. I suggest you find a technician where you live.

[@jonathanpalmer155]

@@audionautica6843 Isn't it usually only ones with single-ended power supplies and to take away the DC-offset?

[@tim0steele]

That refurbishment you did on the power transistors looks incredible.

[@audionautica6843]

Thanks for watching!

[@MrPINKFL0YD]

This model was the first amp I bought and I loved it.

[@mlbabineaux]

I have a FLuke 45 I do this kind of work with. Great meter for audio work.

[@tim0steele]

I repaired a NAD 3030 years ago, it was my first amp repair. Unfortunately damaged my speakers as it was putting out DC from the speaker terminals. Ended up having to replace the power transistors and the drive transistors as well. Thankfully in those days schematics were easy to come by. I think the speaker repair cost more than the amp repair in the end! I traced the cause to a bad earth connection from the PCB to the chassis, the wire was held by a screw which was loose. This caused occasional spikes when on phono input and destroyed the power amp.

[@audionautica6843]

Thanks for watching!

[@danielbarrera6880]

Excellent repair !!!!

[@Stefandejager01]

Loved watching - great job.

[@johndyson4109]

My 80s PIONEER amp. @110-watts per side @ 8-ohms. hisses a bit after 10-oclock it always has.. It's not a loud hiss but you can hear it a bit.. I don't think there's anything wrong with the circuit... You do great work...

[@frankiejkh1]

Very nice repair and very nicely explained

[@James_Bowie]

Upside-down mounting of a PCB containing a power resistor -- priceless.

[@audionautica6843]

Yes, it was a warming experience.

[@bennylixballtiti3606]

You do it all very well. Thank you for several hints..., i will follow your channel now..

[@audionautica6843]

Thanks for the sub!

[@PirxthePilot]

I am slowly refurbishing my first serious amplifier I purchased 24 years ago Audiolab 8000s. Definitely a different design philosophies on the inside here vs Audiolab - that looks really modern or just a really clean design in comparison.

[@user-vs7cw2rg7r]

Great video, very informative. I have one of these, had it for years and it sounds great, apart from transformer hum. Thinking of giving it a service so this is very, very useful. Thanks 👍

[@mlbabineaux]

Unit has some United Chemi-Con caps. Good stuff

[@babylemonade2868]

Cool video I’ve got 3150 that needs a service,still sounds good though

[@audionautica6843]

Thanks for watching!

[@santospoland]

Pity that you didn't measure the transistors for us neophytes :) Great video!!

[@therealchayd]

Having brought an amp that was released around the same time as the 3020 (Denon PMA350) as a gift to myself for geting my first proper paid job, I'm starting to feel old now these are referred to as "vintage" 😅

[@timhull8664]

That Amp was the dogs b locks, in the early 80’s launched in 1979 I think and cost about £80

[@smokesandalloy9487]

Wonderful. And that's such a cute little Atlas ESR meter. Will see about getting one.

[@jonathanpalmer155]

Made by Peak Electronic Design in the middle of the Derbyshire Peak District, in Buxton, at arguably the highest electronics factory in the UK!

[@eugeniahobbs41]

Excellent

[@Jason-wc3fh]

I believe that the threadlocker you applied is anaerobic. Meaning it only hardens and works its thread locking magic when it's on the threads of the nut/bolt when being put together. The lack of oxygen is how it cures.

[@richardsinger01]

Thats correct, but it will creep into the threads and cure to some extent. TBH I wonder if you even need threadlock, considering there are star washers under the nuts, but better safe than sorry I suppose.

[@jonathanpalmer155]

@@richardsinger01 Hell, for what it costs for the application, why not!

[@simeonbanner6204]

I really admire you folks who fix things. It's a great skill. I wanted to do electronics at school but they dissuaded me as I wasn't good at maths. All the items I see dumped here in Britain. In the street even: vacuum cleaners, consumer electronics. I guess it's all driven by product life cycles. Apparently, under huge pressure, Apple is now allowing people to fix their phones.

[@Hank_E]

The problem is, atleast here in Finland, that you’re not allowed to repair 230 V stuff unless you have all necessary rights which are quite difficult to get. I work with industrial automation but there we have one engineer in charge of the rights and at home I’m not even allowed to make an extension cable. Also to do this for a living you can’t put 4-5 h on a 5 year old 200-300€ gadget, but yes it’s a shame.

[@richardsinger01]

@@Hank_E in the UK house electrics are off limits for amateurs, but repairing electronic items is perfectly ok. I have no idea what controls there are regarding repairing stuff on a commercial basis. You'd need liability insurance at the very least, but possibly qualifications too - if such still exist.

[@andymouse]

Don't let the 'maths' bother you as you can enjoy the hobby with minimal abilities, just some basic stuff.

[@jonathanpalmer155]

It doesn't need to much maths knowledge for the Ohm's Law calculations - you'll use a calculator anyway. It's once your start discussing phase lead/lag where you need trigonometry knowledge. There is nothing to stop you improving your maths ability - it usually depends on the quality of the maths teacher who does not know how to teach. The difference between a Good maths teacher and a bad one is frightening...

[@jonathanpalmer155]

@@richardsinger01 The course is C&G 2240 Electronic Servicing Course - there's 3 levels: it's gained a '0' since I did it 40 years ago [I only just realise it was that long ago!] The biggest problem/limitation is miniscule surface-mount components - resistors/capacitors/inductors - that are the size of the snapped-off pencil tip. Too small to carry any markings - if you can't get a circuit schematic diagram then you are stuffed and have to make a lucky guestimate at the correct type and value. It should be illegal to prevent electronics equipment being repaired.

[@roerdomp16e]

Hi, Love your video's! You should definitely get a desoldering station. I don't understand how I even did without it. The ZD-8915, very affordable, not the best build but works great!. Nozzles are cheap.

[@audionautica6843]

Thanks for the tip!

[@jonathanpalmer155]

What, not use solder wick and miss out on that 'burnt thumb and First finger tip' sensation?

[@roerdomp16e]

@@jonathanpalmer155 yeah and stench, lost pads and loads of mucky flux... love it

[@andymouse]

Oh the venerable 2N3055 ! used in everything from Tesla Coils to High End Budget Amps, nice relaxing video, shame about the test speakers and would have been nice to see a sine wave and get the noise Figures...cheers.

[@audionautica6843]

Yep - they sure are popular. I did noise figures on a 3120 in another video.

[@andymouse]

@@audionautica6843 Thanks.

[@viktor928]

Hello, I have similar I believe the first one NAD3020 series 20, my left channel just start getting distorted, my power button gets scratchy when turned on how much will that kind of service cost me would you take on my project? Where are you located? Thank you!

[@audionautica6843]

Hi. I'm in Sydney, Australia. I'd advise against using if it is distorting - these do not have any speaker protection and you don't want to blow your speakers. They are relatively simple to work on, however it is impossible to know what work needs doing until it has been looked at. Sounds like the power switch needs replacing, but there are likely to be other issues based on what you have described. I recommend you find a competent tech in your area. If he suggests replacing all of the electrolytic capacitors as the "solution", find a different tech.

[@santospoland]

One other comment if I may, just a small observation but I can't verify my claim. At the very end of the video it appears to me that the lid was not cleaned up to remove any of the rust that had built up over the years. If I am mistaken I do apologize but it was just to say that ideally all corrosion should be removed to prevent any of it falling onto the PCB and its components over time and to keep the corrosion from spreading. I really liked your video and chose to subscribe. Cheers!

[@audionautica6843]

Welcome to the channel and thanks for the sub! Of course a lot of factors have to be taken into account in making a video and repairing an amplifier. It just isn't possible to show everything on a video, and if I did, people wouldn't watch it because it is too long. I did film pretty much everything for one of my Quad 405-2 videos and the raw footage was almost 3 hours, it was still 1.5 hours by the time I edited it down, and it took forever to do the editing. I don't have time to do that regularly. A repair is not a restoration. You can tell just by looking at corrosion what needs to be removed and what doesn't. This is a low cost amplifier that someone picked up cheap on Facebook market place. He is absolutely over the moon with the result. Thanks again for watching.

[@No_Plastic]

Great video. I have NAD 302 version, the light is on but can only hear extremely low sound if I crack the volume to the max. Can you suggest anything i can try? Thank you.

[@audionautica6843]

Sorry, can't really suggest that much off hand. Try removing the links on the back panel between "Pre-Out" and "Main In" Use a source with a volume control (like a phone) and connect it to "Main In". You should be able to drive the speakers normally. If this works, it tells you the fault is in the pre-amp section. If it doesn't work, then the power amp section is at fault. You could also (with the links installed) see if the "Tone Defeat" switch makes any difference. Also I read somewhere that sometimes the Soft Clipping switch on the back panel can give problems - try cycling it a dozen times and see if that helps. Whatever you do, don't go spraying WD40 into switches or controls. Only ever use proper zero residue electronics switch cleaner. Good luck!

[@No_Plastic]

@@audionautica6843 Thank you so much, I will give those a try 👍

[@zyghom]

AMAZING change in the look (and maybe the sound). However, if you have added red loctite instead of blue, the sound would be warmer a bit ;-) (blue is always cold(ish))

[@audionautica6843]

I should have used oxygen free loctite

[@richardsinger01]

Single crystal silver plated oxygen free loktite at the very least.

[@terencemcculloch3294]

The silicon used on that trimpot may have been the acid cure type which will corrode metal.

[@Jason-wc3fh]

Yes. The corrosion is actually from the silicone itself. Definitely not the right product to have used on this.

[@andrewhenderson6219]

Hello Stephen . Thanks for the Video . I am a New Subscriber. What part of Australia are you from . And are you a Qualified Electronics Technician. Cheers Mate.

[@audionautica6843]

Hi. I'm in Sydney. I'm an electronics engineer. I don't work in electronics anymore. This is my hobby. Oh, and welcome to the channel!

[@MINECRAFTandSEB]

why is there always a sharpie mark on one of the big capacitors? Mine has one as well

[@audionautica6843]

I hadn't even noticed - might indicate something during Factory Acceptance Testing - very common to do something like that.

[@nathenduplessis9645]

Good day we have the same amplifier one of his channesels has blown where can we buy parts or get someone to fix it we are from south Africa

[@audionautica6843]

You will need to find a tech in your area who can work on it for you. I am in Australia.

[@izzzzzz6]

Any speaker protection in that thing?

[@audionautica6843]

Nope.

[@bertramlefarge69]

Sweet sounding and powerful for the rated wattage, just the poor build and birds nest wiring let it down.

[@audionautica6843]

Correct - but that cheap build is also what made it accessible to the masses and why it became the most popular amplifier in the world.

[@dominikkrauze6812]

Hi. How check and adjus the bias in the NAD 3020A. Thanks

[@audionautica6843]

You download the manual from hifiengine and follow the directions, or you take it to your local audio tech and get him to do it. Problem is if you are not sure what you are doing you can blow your amp. I once blew an amp while trying to adjust bias because I didn't realise my ammeter had gone open circuit

[@Radfordperson]

@@audionautica6843 I blew the series power regulator transistor by accidentally causing a short, when measuring the output stage bias on a Quad 303, fortunately, this was the only fault I created!

[@audionautica6843]

@@Radfordperson Yep - we learn from our mistakes, especially if the magic smoke is involved.

[@felixlaboy1453]

Amazing video buddy. Are you in the NY area.

[@audionautica6843]

Thanks - no, I'm down under.

[@felixlaboy1453]

@@audionautica6843 oh ok buddy. I’m Trying to find someone to look at me pioneer sx 1250. It works fine. Just a few lights in the front not working and the left speaker plays with a little static sometimes.

[@audionautica6843]

Nice receiver! I'd find a competent shop in your area. Lights should be easy. Static could be a few things. But definitely worth keeping on top of the maintenance for such a lovely receiver.

[@felixlaboy1453]

@@audionautica6843 Thank you I really appreciate the reply and the advice buddy keep up the amazing work man thank you once again

[@windymiller6908]

Deepest condolonces to your family.

[@tigerbalm666]

"Not too bad"??? I own several receivers made in 1973 that looks brand new!

[@nathenduplessis9645]

Where are you from that you maybe can help us with the amplifier

[@audionautica6843]

I'm in Sydney, Australia

[@georgeap4893]

Great content on yr channel! But you seem to have far more ads than anybody else I’ve encountered……

[@audionautica6843]

Thanks for supporting my channel!

[@ianhayward4386]

You could have put the star washers in vinegar, it would have restored then sufficiently for this restoration.

[@audionautica6843]

I've never tried that - I'll have to give it a go.

[@gdwlaw5549]

both my NAD's failed. Regret not keeping them. Thank you

[@audionautica6843]

Thanks for watching! Sorry about your NADs.

[@karlrawstrone8568]

It happens with age. So long as you didn't want any more children, you would only need your 'nads for cosmetic reasons. I gave one nad to a friend years ago.

[@gdwlaw5549]

@@karlrawstrone8568 sort of taking conversation DOWN a level

[@karlrawstrone8568]

@@gdwlaw5549 Attenuating ;)

[@andymouse]

@@karlrawstrone8568 Lol !

[@schlass265]

Noob here. Why did you have to de-solder then resolder something when you ajdusted the amp?

[@audionautica6843]

Whether you need to do this will depend on the circuit, but the service manual should always make clear what the procedure is. You are always trying to measure the bias current (in a BJT final configuration) as a BJT is a current controlled device. Biasing sets it so that the transistor is always turned on, because when it switches on and off it will cause distortion. In some amplifiers, you can just measure straight across a series resistor - no links required. In some you are required to actually put an ammeter in series and measure the current. Others (like this one) will have you remove a link. From memory (without looking at the circuit), I think there is a resistor there that is used to measure the bias current. The resistor is only able to hand the bias current, if you left it in circuit at normal power outputs for a period of time, it would burn out. Hence the reason you short it out again once the bias has been set. Writing this all from memory, so its not guaranteed, but you get the general idea...

[@schlass265]

Cool, thanks a lot! What's a BJT?

[@audionautica6843]

Bipolar Junction Transistor.

[@markwhitfield5412]

LOTS OF dry joints all over the board rings around joints etc etc. need a good seeing too, that's what she said...

[@audionautica6843]

nope.

[@santospoland]

As you adjusted the bias it would have been more practical to show us how you were adjusting the pots as it would have been more instructive. You could have simply introduced how you were making measurements and simply informed us of the values as they went up or down relative to the pot adjustments. Just a little note I suppose.

[@boblambert8985]

Great work, but it's apprise, not appraise.

[@audionautica6843]

You've lost me. Can you apprise me of your appraisal?

[@barrybradfordlocksport]

Audio to low to hear you

[@thethirdman225]

Just to clear up what has become a common misuse of terminology on KZbin. There is a difference between corrosion and rust. While both describe oxidisation, there is a difference, just as fire is also oxidisation. Rust affects ferrous metals, iron and steel. If that lid is made of steel - and I’m sure it is - then that discolouration is _rust._ Corrosion affects non-ferrous metals, aluminium, copper, tin, etc. This actually _does_ matter because the chassis will almost certainly be made of ferrous metal, while there will be a lot more non-ferrous metals inside. Thumbs up anyway.

[@audionautica6843]

Yes - it's rust - but there is a difference between surface rust and more serious rust. If in a damp or humid environment it will proceed at a faster rate. In a dry environment, it should proceed very slowly. So then one has to assess - for an amplifier of that age and vintage is it worth stripping back and repainting the lid, or more to the point - is the owner prepared to pay for it. I wouldn't - not for that amp, anyway.

[@thethirdman225]

@@audionautica6843 My point is that while the process is basically the same, the terms are not interchangeable.

[@MrJan123an]

MADE IN TAIWAN...

[@MINECRAFTandSEB]

Man the 3120 has such a messy and bad looking interior, my 3155 is golden in comparison.

[@zaphod_beeblerox]

wtf are you cleaning transistors and replacing washers???? ffs

[@audionautica6843]

1) Because this amp is over 30 years old and thermal grease dries out over time. It then no longer transmits heat, the transistors then overheat and die. 2) If you are going to properly test the transistors, you need to take them out, in which case the thermal grease needs to be replaced anyway. 3) Because silpads are a much neater and more elegant solution than the thermal grease. I once had a computer whose' network name was SLARTIBARTFAST. Had no idea it was from Hitchhikers' until you made me Google it just now!

[@Radfordperson]

@@audionautica6843 Great program that, The Hitchiker's Guide to the Galaxy. Love it!

[@rmle23]

Very poor quality electronics made by Tatung.

[@audionautica6843]

I guess it depends on how one defines quality. When I studied quality control, it was defined as the ability to consistently and repeatedly produce a product within its design specification. NAD did that - they made decisions about a price point, and in doing so the NAD 3020 became the most popular amplifier in history. I myself prefer to see amps that look like they are Mil Spec, but hardly anyone would buy them if they were.

[@writenamehere0000]

in your topic "i" is missing