Technics SU-3500 Amplifier Repair

Mark repairs a subscriber's 46 year old amplifier. It certainly has a few suprises in store, and it doesn't help when Mark screws up!

[@Flavum]

I know next to nothing about electronics, but these videos are captivating. Mark's knowledge plus his pleasant demeanor keeps drawing me in. 😀

[@hernancoronel]

You will eventually learn!

[@Flavum]

@@hernancoronel I used to know Ohm's Law. Maybe that will help. 😀

[@gyrgrls]

@@Flavum It will eventually wear down your resistance. You might even meet a few cool conductors along the way.

[@Ian-Steele]

I agree with you. I have a basic understanding of electronics, but Mark makes it more accessible.

[@peterream9437]

Doesn't he just...It's years of experience right before your eyes. Can't learn that from a book....

[@dmichaels111]

I'm an old troubleshooter of electronics from the 80's. I miss those days and I relive them through these videos. More please ...

[@JonnyMac351]

Same repair tech 80's - 2000 it brings back memories for me too.

[@aalexjohna]

You are a liar and a fantasist.

[@philiptate8810]

Will someone PLEASE give Mark his own TV show!!

[@Petertronic]

KZbin is better than tv these days

[@HansDelbruck53]

A TV show would have commercials. Who wants that?

[@synaesthesia2010]

@@HansDelbruck53 Mark has commercials too. if you don't see them you must be using an adblocker

[@HansDelbruck53]

@@synaesthesia2010 I must be.

[@jtaylor8606]

He's already busy enough running House of Frasers in his spare time

[@pantelisEVs]

Beautiful amp! Great repair! Thanks Mark and i hope you are doing well!

[@gingerbreadaudio]

I'm blown away with your test equipment. It's a great video 👍

[@patprop74]

Mark, you really know your stuff, and you got all the fancy tools that help!

[@simonbailey7111]

Great work as usual a master in electronics can’t wait to get my device back. 👍

[@tenmillionvolts]

It's about time you got a tricky one. I was beginning to think you only filmed the easy ones, haha! Almost all of my repairs are as bad as this or worse. Suppliers have almost given up on support for repair now so it's up to us to fix them any way we can.

[@andrew_koala2974]

only recorded the easy ones NOT only filmed the easy ones In the event, you have been in a coma for four decades FILM has not been used since about 1980 You have to update your terminology and vocabulary. You can do that by reading those things known as BOOKS and most importantly - paying attention to detail

[@tenmillionvolts]

@@andrew_koala2974 Please accept my SINCERE apologies for OFFENDING you. I shall attempt never to comment near you again so that you do not have to put up with the filth that is my ill-educated self.

[@yanfishtwig2356]

@@andrew_koala2974 Nice example of pedantry

[@BryantBrothers-gm1qx]

Nothing EASY about any of these repairs

[@yanfishtwig2356]

@@BryantBrothers-gm1qx he makes it look easy or is it that hes at ease with the work:)

[@paulwooller4524]

I always look forward to seeing your videos - totally absorbing to watch. It’s almost worth me blowing something up just to see you repair it. Great stuff Mark👍🏻👍🏻👍🏻👏🏻👏🏻👏🏻

[@eltrash]

I like your smile and positive attitude throughout your repairs, even when things get difficult you never swear or anything

[@Ilovetosingem]

Very nice mark. Takes me back to when I didn't have the circuit diagram and just used a multimeter to track the components and drew my own diagrams. Thanks and stay safe you and yours.

[@careycummings9999]

I just love this channel! 30! years after getting my AAS in Electrical Instrumentation Technology, I can follow along while you troubleshoot cool stuff. I don't work on electronics for a career. I am more of a CNC repairman and Industrial electrician, but watching you patiently go through these old amps and other audio gems brings me back to my college days. And thank you for leaving your infrequent mistakes in! We all make them, so its good to be reminded that sometimes s%*t happens, but its ok, just carry on. Cheers from Long Island, NY.

[@europort5784]

I like playing a game in my head - Everytime Mark laughs when something doesn't work, I yell obscenities. Love the content Mark!

[@IlBiggo]

Thank you for restoring the Universe's balance. No technician should abstain from yelling obscenities when things don't work. Mark laughing about them could cause a crack in the space/time continuum, or something.

[@scottsgear]

Woohoo! I'm such a fan, thrilled to see a new video from you. Thanks for sharing your knowledge.

[@stevejones9945]

Great video Mark, always good to see fix's are not straightforward but, by process of elimination combined with your knowledge it makes for a captivating video.

[@andrewwturner]

It is always a treat when you release a new video Mark and you really didn't disappoint with this one! Can't wait for the next installment.

[@paulhalgarth1164]

That was a tricky one, Mark. Thanks for sharing. Looking forward to seeing if the repairs worked...

[@pablov1973]

I'm a big fan of your videos, I never seen so much attention and care for the details. Your dedication is far beyond to what an equipment owner usually expect. For not tell anything about amazing sense of humour, maybe the most happy technician around the globe.

[@pac1085]

Awesome! I love seeing the use of the curve tracer and how as great as the dca75 is, a real curve tracer still has its uses. I had a similar experience recently with an intermittent transistor that the 575 helped me find

[@SoddingaboutSi]

The SU3500 is a super amp. Rated at 43W into 8 ohm and capable of driving 4 ohm loads with ease. Did a full recap on mine and it sounds wonderful.

[@bazuka-rf7zr]

А есть люди, которым не нравится его звук.

[@danielknepper6884]

When in doubt recap it out😅

[@chrisyates8115]

The suspense! Fascinating work Mark!

[@hydorah]

Wow been a tough one so far! I'm amazed at your ability! When you held up something black and Technics I thought I knew what was in store, but I was wrong! It was a lot older than I expected. Love the construction of that amp and how over sized and understressed it is for 100w

[@fullwaverecked]

Always a pleasure Mark! Looking forward to your next. Cheers!

[@johnfitzpatrick2469]

G, day Mark from Sydney Australia. I really enjoy watching your circuit board investigations, testing; * Diodes * Capacitors * Resistors * Integrity of traces and solder connections * Oscilloscopes (frequency peak to peak) two independent channels. * Flow of voltage and amperage to specific specs of each component. * Dis- assembly and assembly of cabinets ( with repair and manufacturing of controls) Thank you for your time in producing these videos, sir. 🌏🇭🇲🤨

[@langerstrains9460]

Interesting amp there and what a cliff hanger.. can't wait for the next episode

[@johnsampson1096]

Hey, Mark, another great journey on repair, Thanks! Those three pushbuttons on front are for matching the output impedance of the phono cartridge, usually magnetic to the phono input of the amp. I still have a ton of vinyl records, especially 45s. Cheers............

[@postersm7141]

I would be ecstatic if I could get my old 70s amplifier down to -10 mV DC offset. The fact that you got that thing down to 000.33 is freaking amazing. This is a testament to the old early to mid 70s gear. And of course your knowledge and ability to do the repair!

[@I-LOG]

You really got me with that cliffhanger! Can't wait to see what happens next, love your videos!

[@gbanger2575]

I have an early 80s Harmon Kardon amplifier that has 2 phono inputs and selectors for the different cartridges, hi and low filters etc. Lovely sounding old amp. Love your videos. Keep up the good work, sir!

[@cjh0751]

A mend it Mark video on a Monday evening. What a treat.

[@audio-play]

You explained everything very well, Mark. That's what I expected. Bravo, thank you.

[@LBytCH1]

Thoroughly enjoyed this video - great work Mark!

[@mno555]

I love watching your videos and I wish I had your skill and knowledge!. My family also like to watch even tho they aren’t particulary interested in electronics. You are so positive and it affect us all😊

[@tony359]

Cliff-hanger! Great repair and I love the modular construction!

[@HG80369]

Great vid Mark. The golden age of Technics amps.

[@JCWise-sf9ww]

Mark, I can relate to your repair work on newer and vintage electronics. Had that happen to me, find the problems only to have something else needed fixed, when you think it's all fixed and then find out you screwed up something. Can't wait for your next video on what happen to the Technics stereo amplifier.

[@spoonsmith9506]

Really enjoyed this. One of the better fix it editing I've seen. Love your little chuckle too Mark, lol.

[@JamesE707]

The Towers International Transistor Selector ... wow, you've brought back memories! I've not seen that for .... many decades!

[@WayniKlaru14344]

Outstanding !!! Brilliant video. Very informative and educational. Love to see the next one. Thank you so much.😊👍

[@larswillsen]

You make everything look so easy .. we viewers feel very helpful too 🙂

[@Grottolova]

Ahhh YES! I cherish these repair vids!

[@darrenwendell1723]

A pleasure to watch your expertise.

[@kwd-kwd]

love the repair vids please keep doing them.

[@lssoundcompany5034]

Mark, you're Wonderful. You've Won the Watson Watt Outstanding achievement award !

[@robwatkins1547]

Excellent as always, I like your honesty, others would blame faulty chips etc but not you, I've used the wrong resistor is your reply. That puts confidents in people knowing that they are dealing with an honest person, but in the same sentence, I wouldn't like to play you at cluedo, your like a real investigator, no stone is unturned.

[@BrianLyod-nj1vg]

Brilliant video and and you explain so well. I'm only a hobbyist but as I teach myself I watch your videos and slowly the stuff you don't explain in your choices I am answering it myself. You would make a very good teacher and you convey brilliantly the practical application on the bench of just repeating the basic questions of simple circuits. It years and a long time to have the faith on the meters to actually repair stuff as you do, but it's good to see great knowledge applied and make it accesable for the journey. Inspiring stuff mate x

[@paulb4uk]

Superb work so far, they made it to be easily repaired well thought out design.

[@tbirdsteve1]

Great stuff Mark, very entertaining. Wish you could fix my 90's Technics stuff.

[@superbad123]

great Mark, can't wait to see part2

[@nicodemoseletronica4306]

I always follow your work, I'm passionate about electronics here in Brazil and it's very rare to repair older devices, congratulations on the work......beautiful bench, my dream, God willing, with my oscilloscope....

[@jameskolar9655]

Love your little chuckle when you detect an obvious fault, then you explain it and instantly fix it! You are speaking a language I don’t understand, but wish I did. Ha ha! I enjoyed this vid. Thank you.

[@CuriousMarc]

That is such happy restoring! Nice job!

[@montageproductions]

Fascinating process for the trouble shooting, but also an amazing but tedious job of setting and resetting camera angles!

[@mixolydian2010]

Cheers Mark really enjoyed the video, can see from all the cuts a lot of work goes into the video editing. All the best.

[@lifeisfuneh]

This was fun to watch! Thanks!

[@Jesselovespinball]

Thank my lucky stars !!!! Another mend it Mark video !!!!! Best Monday ever !!!!!

[@Raj-gn7xm]

Absolutely love that somebody wants to dial down deep into these vintage electronics. I hate to see waste and love it when somebody can make an old amp new again.

[@Jonathan_Doe_]

The stereo mode switching is probably great for those 60’s mixes that have instruments/vocals hard panned. The L+R mono would stop you having Jimi coming out of one side, the drums out of the other… Or the individual L or R mono modes would let you isolate the hard panned instruments.

[@SierraLimaOscar]

If I recall correctly one of the argument for that switch (which was popular on amps of the period) was that you could use two amps as individual mono blocks and double the power.

[@Jonathan_Doe_]

@@SierraLimaOscar Ah yeah that makes a lot of sense!

[@godfreypoon5148]

It's also great for when some muppet youtuber takes an unnatural liking to one channel or the other.

[@Jonathan_Doe_]

@@godfreypoon5148 That *my left ear loved this video* issue seems less common now, think it must’ve been a video editing/codec issue.

[@dalemettee1147]

This amp and the tuner that went with it were in the same look as a reel to reel tape recorder RS 1500 US. When stacked together, they looked amazing!

[@BPantherPink]

Mark is a Laughing Buddja with the sweetest smile !! Well done on the beautiful moulding !!

[@LeslieMacP123]

Someone gave Mark a beautiful mind and fantastic hands. He can fix everything. He s a master. He s a celebrity of these thematic channels. And as for all the celebs we want to watch more and more: Mark at the grocery store for example, or Mark taking a boat. That would be brilliant.

[@aalexjohna]

Mark taking it up the back passage?

[@AllenCavedo]

Very nice! Excellent trouble shooting logic. Great bench gear.

[@bussypaul7326]

Great work! Waiting for the missing knob replacement!

[@Jesselovespinball]

Leaving us hanging!!!! Lol can’t wait for the next one Mark ! Keep up the great work !

[@peterlarkin762]

I always understood the 13A fuse was to protect dead shorts in the cable, and most hifi has a mains glass fuse rated correctly for the device. So the glass fuse is the device protection really, and non UK versions won't have any such fuse in the plug. Also, the ceramic sand fuses only go down to 3A which would still be too high a rating for many amps. Great vids, thanks Mark!

[@bobfrankish8883]

Great vid Mark. I owned one of these back in the day and loved it. I have also repaired a few. It was much easier back then because all the semiconductors were available from Technics. It has reminded me that I must get round to repairing my old Sugden power amplifier and pre-amp unit. It's only been broken for about 12 years, so no rush! Incidentally, I have 2 sets of the Sugden test equipment, low distortion signal generator, AC millivoltmeter and distortion analyser, don't know if you've come across them or remember them. I live in Huddersfield and Sugden were based just a few miles away in Cleckheaton, so a lot of old Yorkshire engineers used to have these. The sig gens are quite amazing for their day at 0.02% THD as I recall.

[@denisconnolly5064]

Mark, many years ago I discovered a really good alternative to using a multimeter to test components. It required a 'scope to display the test results but it was quick and effective. The 'scope displayed the properties of the component under an AC test current. A diode gave a right angle, a resistor a diagonal, a capacitor a circle. Subtle differences in the display revealed leaks, high ESR, etc. A great bit of kit.

[@mohsentabouna6401]

it's a curve tracer, it's actually built in on some old Hameg scopes labeled as component tester. you can have any scope to display a curbe trace in X-Y mode using an ''Octopus'' circuit

[@mikeh2520]

@@mohsentabouna6401 No, that Hameg scope has a component signature analyzer and not a "curve tracer". Many other people mistake that as well. You saw a real curve tracer in this video @24:30, the type 576. Look at that point again. It is plotting a series of steps of operating points to display the characteristic curves of a device in current / voltage axis. A signature analyzer is looking at devices in a single operating point area. Even the DCA75 transistor analyzer that was shown in this video has an actual real low current curve tracer that you can use by USB to see the characteristic curves of devices displayed on your computer. But the DCA75 can't source enough current to be useful for matching output transistors and is only good for small signal devices. Transistors need to be tested and measured at their intended operating point in the circuit for current and voltage to find a matched pair with similar curves or to get a good reference check.

[@RodrigoLuques]

I was missing your videos Mark! Regards from Brazil 🎉

[@amplituhedron5582]

Great video, even greater news there is a second installment coming.

[@Alexelectricalengineering]

So nice, amazing troubleshooting 👍👍👍 Greetings Alexander

[@paulio0898]

I love your videos, such a great style 👍thank you

[@erickuyper3087]

your videos are very educational

[@iantyler4045]

I always suspect NTE replacements but those look okay. Nice fault finding and very entertaining as usual. (I wish I had a curve tracer!)

[@myturkishlife1777]

These technics amps get a slating by some folk, but this seems pretty well laid out... Great video 👍 Kind regards from Turkey 👍🇹🇷

[@Theoobovril]

Great as usual, Mark.

[@wdavem]

These videos of yours are at the top of my list for 'handling real world examples' because of your presentation, documentation and editing. Also it sounds like you are using a venturi de-soldering, which is something I've only imagined before. I did build a similar device for killing poisonous spiders long ago (equally effective), but it's comically enormous for electronics de-soldering (1.5 meters long).

[@wollaminfaetter]

That was quite the mystery from Mark - The Electronics Whisperer (y) Thank you very much! I understood nada, but really enjoyed it 😁

[@0ActionMonkey0]

Amazing patience & knowledge, i so wish i had this intelligence!

[@anjkovo2138]

Very Interesting. I enjoyed watching that 👍👍

[@joefarr3304]

Cliff hanger....... ohhhh mannnn.... I repair stuff from time to time, nothing like you, just my own junk usually, but I would never have found that transistor with the thermal fault. I would have put it on my atlas tester, it would have probably said it was fine and I would have moved on. Brilliant job sir and great videos.

[@michaelchapman4269]

Absolutely love your videos Mark, if I knew half of what you do I’d be happy. I have a vintage NAD amplifier that could do with a service and a little incandescent lamp that need replacing behind the VU meters, would love to see you repairing it on here (obvs would pay!!) let me know if you are not overwhelmed with stuff!!

[@wildskel6350]

What I like about this, apart from the mad skills the dude has, is when things aren't working he's very philosophical, just chuckles and tries something else. Even when I'm attempting easy jobs I get the hump something fierce if it isn't going to plan.

[@derekblake9385]

Your knowledge is incredible.😮😮

[@SPINNINGMYWHEELS777]

very cool Technics - it has options that my Crown IC 150A has on it.. I love the ability to tune each channel frequency and quick reverse stereo or mono dial ..but the Crown is a Pre-amp super clean .

[@conhawks]

thoroughly enjoyed that mark and learnt some, clyde.

[@gordonwelcher9598]

In a Japanese amplifier, I have seen a plastic transistor become intermittant and put the entire supply voltage on the speaker. Several angrily placed taps with my Widlarizer rapidly changed it's geometry.

[@godfreypoon5148]

In that case you should have diffused its junction around the whole workshop.

[@AccuphaseMan]

The two phono inputs are generally for two different tonearms and not necessarily separate decks. It's fairly common to have one arm for MM and one for MC or a stereo and mono cartridge.

[@weevie833]

I'm going to use "knackered" for something. As always, great video, Mark.

[@mnicholson2003]

Dig the new editing and prod!! Love your channel!

[@mikeh6876]

I really love to see the way you work......... Note: the 2SC4793 is an obsolete part. You can use a MJE15034G - cost about $1.50 U.S.

[@davidc6459]

Great video and great repair, I'm not far away from you, in Penn!

[@kerrygleeson4409]

Fantastic Mark so interesting thanks for sharing 🦘

[@AC_Milan1899]

Beautiful piece

[@johnfloy]

Mark i just really enjoy your repair videos. I still don't understand how you are able to keep track off all those screws taking apart all this stuff ;) Cheers!

[@chug70]

Fantastic Mark !

[@Lhenndyn]

There is always a small dead transistor hiding somewhere ;) Tricky one ! Perfect job.

[@3rdandlong]

Those Technics Amps were gold when it came to audio equipment. I'm a product of the 70's and 80's so I remember them well. Was hoping you were going to test it by cranking up some Led Zeppelin. Technics amps were meant for listening to Zeppelin tracks. I wish those were still around new. Such an iconic piece of equipment for audio.

[@nickm8494]

Best chuckle in the business.

[@technodaz]

Great work as always! pleasure to watch. I have an amp I'm trying to repair but the manual reads like bloody stereo instructions. I wish I had your level of skills or deamination , nothing worse than a manual that says the problem is here but good luck finding it. I've tried tracing it back so many times and I just can't get my head around a 300 page pdf.

[@joe1569]

Curve tracer was nice help. Great technique