DR #51 - Pure Electronic Troubleshooting with an NAD 3240PE Stereo Amplifier

[@supermarioisacat]

Long time audiophile and repair video connoisseur here, only recently ran across your videos. _Really_ enjoy your concise, no fluff, straight to the point approach. Not sure why you don't have a bazillion subs, but it's NOT because of lack of quality of your content. Don't change a thing and just keep cranking them out - you've got a great recipe.

[@dualityrepair4770]

I really appreciate this. A little feedback goes a long way.

[@paulskvorc3627]

Totally agree with your sentiment and is reinforced by famed Paul Carlson's comment below. These videos for a budding hobbyist like me provide succinct, logical instruction. Job well done, and I look forward to more videos and deserved subs...

[@Mac-t4y]

Most of the equipment that Duality has presented in this channel has: Low $ value due to age, OEM no longer support. I do recommend to work on McIntosh products which still in circulation even as old as 40 years old and McIntosh is one of the product that increase value over time.

[@THOMMGB]

That was the best 7 minutes watching you troubleshoot this amplifier. Amazing. You make it look so easy, when, in fact, it's not.

[@dualityrepair4770]

Thanks @THOMMGB.

[@wedger1]

Great video, from an electronic engineer that owns the same amp, logical steps, justified in every decision with facts, no conclusions being jumped to.

[@lcagee]

One of the best amplifier repair videos i have seen. Thank you.

[@Ro32da72]

So easy to follow, and some great fault-finding tips along the way. Also; no messing about; straight through the diag and on to the repair - great job.

[@rickjames6948]

Okay, I'm IMPRESSED. Way to break it down smartly and in record time.

[@raygianelli3612]

Another great video. No cereal or filler, all red meat! You've got the best short form videos (which I'm a big believer in) I've ever seen on KZbin.

[@dualityrepair4770]

Thanks Ray. Plenty of people love the long-form videos. I enjoy them myself. But like you say, everyone's busy and time is unbelievably valuable, so I like to keep mine concise. What I'd love to do one day, or see someone else do, is to post 2 videos at once. One long-form, one short-form, each documenting the exact same repair, and see how they perform head-to-head. It would be an interesting experiment.

[@TravelOutlook]

Thanks Nick....loved the red "x" through the tested sections.

[@dualityrepair4770]

Thanks for the comment. It's satisfying to reduce an issue from 100s of possible sources to just a few.

[@mstorrente]

I like your direct style for explaining your method. Goodyear Jobs. Thanks.

[@MrCarlsonsLab]

Great troubleshooting!

[@dualityrepair4770]

Thanks Paul

[@SuperHyperExtra]

Approved by the great Mr. Carlson. Quite an honor!

[@musictypefoundry7345]

This is awesome. Well explained and easy to follow. Can't wait for the next one!

[@dualityrepair4770]

I appreciate the comment. Very glad you found it easy to follow.

[@ianmacpherson8385]

How cool was that? Highly informative and great delivery. Looking forward to the next installment.

[@dualityrepair4770]

Thanks Ian. Glad you found it interesting.

[@pantelisEVs]

Once again a very entertaining and informative amp repair! Thank you

[@dualityrepair4770]

Glad you enjoyed it @pantelisEVs

[@pascalphase2556]

I love your vids, amazing troubleshooting ! you gain a new subscriber from France.

[@afzaalkhan.m]

Excellent and Concise diagnostic analysis. Thank you . Rawalpindi

[@dualityrepair4770]

Thank you.

[@johnbravo7542]

Excellent,thank you for uploading this trouble shooting method.

[@EdwinSteiner]

Nicely explained video. Also your workplace looks beautiful.

[@MMc-p9g]

Fantastic video! So straightforward and clear! This is the first video of yours I have watched. I will definitely check out others. Can I ask if you test ESR values to find bad caps too?

[@dualityrepair4770]

Thanks for the comment and I’m glad you found my channel. I do use an ESR meter as you’ll see in some of my other videos. I didn’t use it here since both caps failed for capacitance.

[@ElectoneGuy]

These 1980s NADs are excellent amps, but they suffer from the use of cheap components that were used to keep the costs down. A full re-cap is almost always necessary.

[@dualityrepair4770]

Agreed. This video only shows the troubleshooting / repair. It will receive a full service (including a full re-cap) before I'm done with it.

[@maryrafuse3851]

Cheap components do not make for a good amp. In the 1970's Sony and others managed to deliver high quality amps featuring great design, build and components. This NAD is a sad little amp.

[@ElectoneGuy]

@@maryrafuse3851 Bullshit. The 3240 is both a powerful and transparent sounding integrated. Rated for 40w/ch, the Power Envelope circuitry with +6db of headroom will easily crank out 160w/ch for real-world musical peaks. And, it does it while delivering excellent sound quality. Their main goal was to counter Japanese flashiness with simple, good sounding equipment at a fair price. In order to do that, they had to sublet out their manufacturing to third party factories in Taiwan and later China that used questionable longevity capacitors.

[@bobisyouruncle1]

NAD is overrated. If 6db headroom is your aim, well, that, nad is good at.

[@maryrafuse3851]

Interesting contrasting this NAD with amps of old that could run for decades without problems. Also the interior build quality in evidence with the Sony TA-2050, TA-F3A and Hitachi HA-330. All built in Japan.

[@darrenmarrable2530]

Thànkyou. I just learned so much good information.

[@gillanland]

Incidentally i also recently purchased 3240PE amp and your video is the only repair video that i could find!. Mine works, those capacitors haven't failed yet but looks like it needs full sevice( very old capacitors, corrosive glue, dry heatsync compaund and darkened areas on pcb from possibly overheating) . If you deside to make a video on full servicing i'll follow your steps. I have a question as well, there are some sort of breakers BK-1,2 A-40 on the output, i guess they are for DC protection but they are not relays so i don't really understand how they work. Thank you.

[@planetpeckham1]

What a super explanation! Subscribed.

[@saarike]

Simply great!!! Thank you.

[@gregpeirce6121]

Very clear and helpful instruction, thank you.

[@dualityrepair4770]

Glad it was helpful!

[@xpump876]

Nice trouble-shooting steps!

[@peterwikvist2433]

Great presentation Sir! Thank you for sharing.

[@midmodaudio6576]

Great video, very useful and informative. Thank you !

[@dualityrepair4770]

Thanks for the comment midmod.

[@simonstergaard]

could you do a video explaining how to inject the sine, and what are those 2 brown things on you wall that its connected to? i want to learn this

[@dualityrepair4770]

Yes absolutely. Good idea.

[@bobmulhiemer7564]

Thank you sir!

[@tjules7]

I like the way you go through that process of elimination until you pinpoint what the problem is. Very efficient. I live in North Carolina; I have an NAD receiver 7400. I have not used it for years and recently, I tried to turn it on. Sounds is coming in and out and at times, it sounds like what you hear when you radio is not using the correct frequency. How can I go about having somebody looks at it? Do you know a place in North Carolina I can go to, by any chance?

[@dualityrepair4770]

Hi Tony. I'm in Minnesota and unfortunately I don't know anyone around your area who might be able to help you. I might look at it if you'd like to send it up. If you want to talk more, email me at [e-mail].

[@test40323]

Huh, nice deductions. How do you find schematics for old equipment like this? Thanks.

[@dualityrepair4770]

Thanks for the comment. HiFi Engine is a great resource for manuals, which is where I found the schematics for this amp. If I can't find what I'm looking for there, or anywhere else online, I've also purchased manuals from servicemanuals.net. Usually they're $10 to $20.

[@test40323]

@@dualityrepair4770 , thank you!

[@Daltondoubledeuce]

Noob like me finds your vids essential

[@giovannipg3000]

Can you help me repairing a marantz amp ( 5.1 dolby )

[@davidstevens7809]

Seems like it should have dc output from that opamp.. and yes it would be see as a fault to the comparator that controls the relay. Im confused why i dont see any zeners being used with those dropping resistors and caps.. I would increase the cap values and the resistor wattage. So it wont happen again.

[@farouqhannibal1916]

Owsome video bro ,can i ask you for help please,am buzzy trouble shooting you a wharfedale wh-va 3447 receiver ,i placed 16v 2200uf capacitors ,with stock limited and i replaced it with 25v 2200if,reconnect all controllerboards.but it was given to me from a friend who tryed to fix it an all components and plugs was disconnected.so its a puzzle.lol.can or do you have advice reconnecting he power switch mode PCB .bcos i cant get any schematics on the web ,for the correct wiring diagram. Would appreciate it from south Africa technician.

[@dpyles9396]

Excellent method

[@adejupe8308]

Great vid pal 😊

[@nun9496]

Nice Neat and Clean !

[@rickjames6948]

Where do you repair guys get the schematics from?

[@bertroost1675]

Many can be found on hifi engine.

[@reinhardengling2227]

Gut erklärt, Danke.

[@dualityrepair4770]

Gerne!

[@peter.stimpel]

Nice lesson

[@dualityrepair4770]

Thank you

[@bobdoritique7347]

Merci for this video.

[@dualityrepair4770]

de rien

[@N2YTA]

Didn't you rule out the power supply when you demonstrated that the power amplifier worked?

[@dualityrepair4770]

Not quite. The power amp uses the other 2 sections of the power supply (43V and 71V). I had to rule out the section of the power supply used by the preamp (20V).

[@briancoish1695]

Nice one.

[@dualityrepair4770]

Thank you

[@quantumkid1097]

Where are you located?

[@dualityrepair4770]

MN (55129)

[@tenminutetokyo2643]

Do a Carver m-400t cube amp.

[@dualityrepair4770]

I did the plain M-400. DR #37.

[@Mr-Speaker99]

❤🎉❤

[@marekwaczynski3894]

So again CA is tricky with low quality-short lifetime caps.

[@jrworpjrworp7254]

Goof video, shows exzellent how to search for faults

[@Hr.0ldenberg]

Moin, der Mann hat absolut keine Ahnung, wie man ein Verstärker vorab prüft. Er hat wieder einen scope noch ein Sinus Generator noch belastungs Widerstände. Somit ist das ganze Video was man hier sieht für die Tonne. Junge Leute, die gerne etwas lernen möchten sollten sich nicht an dieses Video halten ‼️👈 Dieser Text wurde per Ki erstellt und kann Fehler enthalten. Die hauptaussage dass der Mann keine Ahnung hat bleibt aber erhalten!!!!!

[@kilgoretrout4461]

Thanks for these great tutorials.

[@bertroost1675]

I wish you were my neighbor

[@davidstevens7809]

Oh my.. when i saw you use solder wick.. i looked at the ground. The caps cant cause the problem..with them off the board you should still get a voltage on both sides of the dropping resistors.. the caps give you stability. All of the solder looks dry..come on if your gonna teach. Stop blaming the caps. You simply do continuity test and youll find no connection between the rear of the resistor and the pin on the ic.. second thought.. the signal ground has bad connection also..thats the only way the voltage could go up on the other rail

[@helixworld]

If the power supply is unstable, the RC circuit of the tone control can cause it to oscillate. Then the muting circuit stays open and there would be no output. Anyway, I guess that is one possible explanation.

[@KuntalGhosh]

That is the worst heatsink i have ever seen on an amplifier..

[@envisionelectronics]

You have to understand how power envelope works to know why this heat sink is good enough.

[@dualityrepair4770]

This was a very messy amp. Something was spilled in there at some point, that's what some of the residue is on the heat sink. It's a miracle that it works at all. I wanted this video to highlight the troubleshooting and repair only. This amp will be fully serviced before I'm done with it.

[@Andrew-rc3vh]

The internals are cheap all round. 5% carbon film resistors are noisy, ceramics are dirt cheap poor tolerance, even the PCB is cheap. There is nothing at all pretty inside and reminiscent of the build quality of a Hong Kong/Taiwan import of the era. Oh and the hifi mags called it a "Best-Buy"!

[@suatkaleli5075]