Marantz SM-80 Power Amplifier Repair and Restoration

Here's a quick video outlining the repair and restoration I finished on a sweet Marantz SM-80 power amplifier. It required a lot of troubleshooting and repair steps in order to come out of protection and remain stable under different temperature conditions. This is another great power amplifier that can be had regularly for under $300, granted they will possibly need quite a bit of work to get in stable condition. I went into this amplifier thinking it would be a walk in the park to get working, but it took a few hours to finally solve the (many) issues it had.
I have a few other amplifiers with me for restoration and repair that I will be creating videos for, so stay tuned!
Here is a great article outlining repair and restoration of another Marantz SM-80 by the venerable ‪@LiquidAudio‬:
liquidaudio.com.au/marantz-sm...
Marantz SM-80 specifications and manuals:
www.hifiengine.com/manual_lib...
Some inside shots from another site:
insidehifi.blogspot.com/2015/...

[@indranilmitra6535]

Nothing better than watching an old piece of electronic come back to life and perform well. Very satisfying and wholesome feeling! Good job!

[@PrimeHiFi]

Thank you! Glad you enjoyed it!

[@KuntalGhosh]

Rare to find an Indian in these comments let alone a bangali Indian 😂

[@Some_D0nkus]

Amazing work as to be expected. A mirror finish on all solder joints really brings these restorations to a whole new level.

[@Bangkok-ik1fp]

You are the Duke of the Fluke. Just took my Yamaha receiver out for a dusting and thorough cleaning. Unlike your amp this thing has so many ultra tiny smd's and IC chips with traces like thread that reflowing anything would be impossible. Glad I've taken care of it over the last 20+ years. Subscribed!

[@NOMADCREATIVESOLUTIONS]

Marantz is just one of those stylish brands that speak quality even if they dont always deliver

[@michaeljones19731]

They certainly don’t make em like the used to! Solid piece of kit there buddy.And another great job bringing that old gem 💎 back to its former glory. Maybe even better than new! 👍🏻👍🏻👍🏻🎉

[@LiquidAudio]

Nice work my friend and I love the Fluke 8080A, great meter!

[@PrimeHiFi]

Cheers, Mike! You've been an inspiration for me to work on my own gear and upload videos here on KZbin. - And yes! The Fluke has been a great investment for me. I think I purchased it for $200 shipped which was a killer deal. I may get another soon! Thanks for watching!

[@LiquidAudio]

@@PrimeHiFi Thanks Connor, that's really good to hear and keep up the great work! Killer deal on the Fluke, grab a couple more I reckon!

[@pejbartolo2365]

The subframe, the chassis, is used also in marantz PM72.

[@outfield1988]

Beautiful piece

[@nicodenhaak3961]

just found this channel. great restoration on the Marantz. with regards to the dry midrange: the big Cerafine buffercaps are not the best soundwise. they make a piece of equiptment sound dry, dull and a bit boring. the reason for that is that they take away too much third harmonics, which belong in guitars, piano and human voices. the way to go forward is installing Nichcon lkg filtercaps. these have a fast, dry bass response, and a great open detailled midrange. your amp will start to sound really "live" I'm also working in the same field, and experimented a lot with different series of caps. have fun, kind regards from the Netherlands, Nico den Haak.

[@tee-jaythestereo-bargainph2120]

Great Job man ! Subscribed 😃 Thats how you go threw an amp , Great to see younger people getting into 'Pro Serviced'

[@tee-jaythestereo-bargainph2120]

Would love for you to take on my Orginal Never touched @ all Sansui Au 717 integrated from South Korea 1978 The 717 traveled the world And in Great Cosmic shape I have orginal box manuel and Rack Handles still in Orginal packaging never opened or touched inside but I am about to clean Controls for the 1st time Ever - with Dexoit F5 I will never use D5 ever again But I used it alot - 'lessions learned' Appricate the video ' take care

[@jazzbase412]

Big thumbs up! I really enjoyed that.

[@zoinkz8188]

Fantastic work as always!

[@PrimeHiFi]

Thanks homie

[@Chaggy1978]

Excellent job Connor very impressive. I have a Marantz PM-52 SE that has a similar problem the relays won't click at all. It looks very similar to the SM-80 internally, but it's not identical. I think I will have to send it off for someone to repair as I do not have the equipment or knowledge to fix it myself.

[@jitrapornpha5104]

Glorious work

[@jonpatrick66]

Hi Connor. I just watched this video and enjoyed the quick review of the restoration process and end result. Very satisfying. I just subscribed and look forward to seeing you grow and succeed. 👍

[@PrimeHiFi]

Glad you enjoyed it! Thanks!

[@AudioElectronicsChicago]

so nice 👍🏻

[@may_12521]

fantasitc job connor!

[@PrimeHiFi]

Thanks dude!

[@Lenny-kt2th]

9:30 That layout of the subframe looks like it was used for a PM80 (I used to have a PM80SE).

[@brockercheddlie]

I love these vids

[@denisdube8893]

You are really a pro …

[@jmqwert]

Very nice and comprehensive restauration! You mentioned that many of the small signal transistors changed was noisy / leaky. As a Vintage restauration hobbyist, it would be remarkably interesting how you measure/ find those components. Through Thd measurement, signal tracing or just by knowledge? Anyway, keep up the awesome content! 😊👍

[@PrimeHiFi]

Thank you! Finding noisy semiconductors usually involves individually thermally stressing each component and listening / measuring for noise. Leaky transistors can be found a few different ways including using a transistor analyzer. Some "known" troublesome transistors are also easily found by referencing resources online that specify particular part number transistors known to cause issues.

[@martinetkin2548]

Hi Connor, where are you located? Do you repair electronics as a business? Martin

[@Stelios.Posantzis]

1:20 That's nuts... 1:45 and 4:04 Very impressive build inside. Any idea why Japanese amps always go for EI transformers while European counterparts have the de rigueur toroidals? .5:14 Judging from all the parts that needed replacement though, for a less than 30 years' old amp no less, and the flaky pcb tracks, wouldn't you rather the money was spent elsewhere rather than those flash cheeks? (which btw, only you would know about?) 8:30 Yeah, but wouldn't you better have the lid on when taking this measurement so that it reaches proper operational temperature for that extra little bit? Doesn't look half bad now but that was an extensive repair. It needs the matching cd player but I wonder if the matching pre-amp would stack up too.

[@goosgitaar]

Nice

[@mikemmikem2758]

Another great video. I'm sure what made this amp sound even better was taking the THX logo off, and my first thought was just that - why is that even on it?

[@roberthertel5565]

Very impressed with your electronics knowledge, how does one learn ? Are there classes available or is it mostly online these days ? Guess there are always textbooks but I'd prefer classes if they are available in New Jersey 😎. Thanks for the video, I just subscribed 😁

[@PrimeHiFi]

Hi Robert, I am self-taught. Have been working on electronics for the past five or so years. It's a very fun thing to learn. Having a passion for electronics will push you far!

[@roberthertel5565]

@@PrimeHiFi thanks for the reply, sorry mine was so late 😁

[@GraeboProductions]

You can always take electronics classes at your local Junior College.

[@JoeMuc2008]

Cool! Congrats on this bargain! A great amplifier, however I don't really like these solder bridge cascades around the power transistors. I mean, it may look cool but that's about 13 solder connections between each pin of the power input jacks to the power transistors with alternating polarity between them! And another lot of bridges from the transistor outputs to the speaker terminals. It may look clean but personally I would prefer some big fat wires instead to keep the amount of breaky interconnections and possible losses to a minimum. It looks a bit out of place for me in such a high-endish piece of kit.

[@daneprostamo-brown6552]

love ya work and the videos you put out! did you have a reccomendation for desoldering braid and flux for repairs you conduct? i always find in my repair efforts that poor efficacy of desoldering wick results in the most time lost

[@PrimeHiFi]

Hi, thanks for your kind comment. Glad you enjoy the videos. I actually haven’t used solder wick since I purchased my Hakko FR-301 over a year ago. Getting a good desoldering gun has been one of the best upgrades in my audio lab. In terms of flux, I prefer MG Chemicals 835 liquid flux for the work I do, but your results may vary.

[@user-xq2kq1tm2q]

I really like the audio rack you have. Where can it be found?

[@PrimeHiFi]

Not sure! Got two of them second hand. No brand name on them anywhere unfortunately...

[@lesarnolfinis6775]

I have an old Accuphase amp from the 80's I am considering restauration but I wonder what the cost would be in terms of parts/man hours. I guess I would approach an expert.

[@01sapphireGTS]

It would be great to have access to a local tech with your skillset and level of attention-to-detail, and caring. I would be much braver to get into projects. I routinely pass on project electronics.

[@PrimeHiFi]

Thanks for the kind words! Good technicians are hard to come by. Glad you enjoyed the video 😊

[@PrimeHiFi]

Thanks for the kind words! Good technicians are hard to come by. Glad you enjoyed the video 😊

[@denisdube8893]

Wow

[@stevesmyth4982]

Why would anyone design a PCB with so many wire links that each require two soldered joints which in turn introduces unreliability when a properly designed PCB would do away with the problem?

[@davesubers3415]

Where are you located do you do work for others. You do good work.

[@PrimeHiFi]

Thank you for your kind words! My schedule is currently full and I’m not taking in any work, but I have references if you’d like 👍🏼

[@georgekiriinya8597]

Can wrong bias destroy a power output transistor ?

[@MrPONCHO467]

Do you take work I have a Audio Research vt200 that doesn't power up anymore .

[@leonardvld9334]

you listen to Papooz I love this group

[@KuntalGhosh]

I like the look of those green 2sa1910 bjt's. Toshiba don't make them green anymore. Idk why. They kinda look classy with one set having a green color. 2sa1943 also came in green for many years. But they don't make them green anymore None of the new batches i got are green. It's all boring black..😢

[@KuntalGhosh]

Is it worth making clone of this Amplifier pcb for home use?. Is the distortion really that low compared to some of the modern class ab well made designs available.

[@kennethfarquhar8518]

Great job man

[@user-tr3kw7mp8j]

Where are you? I have a Luxman L510 need repair

[@PrimeHiFi]

United States

[@hatimibrahim9220]

Well, that one is built like a tank

[@Mr0Tubby]

I need Jeffrey Dahmer to do this to my brain

[@rolandd5397]

Considering its only 30 years old and having that much bad parts. Insay bad quality in this one. I have 40-50 years old vintage gear dont have this kind of problem

[@PrimeHiFi]

At the time, Marantz was using above average components and had designed the amplifier elegantly. Unfortunately, Elna capacitors were part of what's known as the "capacitor plague" which affected many amplifiers of the 90's and early 2000's, even high end equipment that used them. Elna capacitors are usually very nice and last decades with no issue. This line however had a defect which caused them to prematurely fail. Marantz couldn't have known this at the time. What I do fault Marantz for is the incredibly thin traces used on the PCB that make troubleshooting and repair a nightmare. Either way, at less than $250 all-in, I'd say this amp is a winner. Thanks for watching!

[@MRPricks]

Just a few hundred joints lol

[@audiononsense1611]

So typical of CAPs from this Era (cheep junk) sad...