Kenwood KA-405 Amplifier Service & MORE than Full Load Test.

Mark strips down a 1979 vintage Kenwood Amplifier, sent in because of a bad channel. It turns out to need a front panel service - and its as good as new! Tested to full load, and beyond!

[@JanWesterink16]

You should rename you channel to the happiest electronics guy. I know absolutely nothing about this stuff but it is just lovely relaxing to see you working on stuff.

[@mattym8]

So true. This guy is the jolliest electronics tech on KZbin

[@gogs1606]

him and mr carlson the best ones

[@bobmckenna5511]

I have worked in the field, and I have to agree with you. He is far too chipper to be an actual electronic technician. Maybe because he’s working for them self :-)

[@SergZak2023]

Mark even laughs when he gets zapped by a residual 320v left in a capacitor!

[@weyayemanjoe3082]

😂 Nice one 👍

[@tedmich]

I believe VERY few techs will pull all the switches and pots then ultrasonic clean, oven dry, re-lube and reinstall, there's simply too much chance of breaking an old part that could be impossible to replace. I appreciate your confidence and completeness!

[@pauldavies6037]

I agree it is unnecessary this unit is in very good condition to start with old brital plastic can break so easily

[@analogaudiorules1724]

@@pauldavies6037 if you know what you're doing it is the right thing to do for longevity, with some of those parts, good luck finding exact fitment or old new stock

[@analogaudiorules1724]

@@pauldavies6037 It's the same thing with tech who don't recap vintage amplifiers then cry when one of them shorts out and takes out a transistor, ic or rare transformer you can't find or buy anymore and if you can find an official part is very expensive. An ounce of prevention is worth a pound of cure, this is the difference between a real tech going the extra mile and someone who does the bare minimum.

[@yanfishtwig2356]

Yes but knowing mark he'l just go to the back of his workshop leap on a lathe mold a mold or twizzle a transformer winder and make a new part. Cape or no cape 😁

[@JonPaul]

He's also washing out all the grease on the controls - I never see him replace that. He does spray a coating in on the contacts but damn, I've made the mistake of washing out that grease and it wrecks the feel of the turn of the "knob" (control)

[@lokesh5]

Mr.Mark is dealing & fixing the problems with a smiling face.. so positive in his profession.

[@codebeat4192]

Beautiful amp and repair and service, really love it! Also compliments for the way you filmed the process and progress. It is really a pleasure to watch and your feel for extras/details is exceptional. You are a craftsman that understands added value. I am glad YT recommended your videos. Thank you sharing your work with us, it makes me smile like you always do. 👍

[@fearandloathing.7823]

Beautiful amp and repair and service, really cycling it! Also compliments for the way you filmed the process and progress. It is really a pleasure to watch and your feel for extras/details is exceptional. You are a craftsman that understands added value. I am glad YT recommended your videos. Thank you sharing your work with us, it makes me smile like you always do. 👍

[@michaeldibb]

Always good to see a new Mend it Mark video and nice to see your subscriber numbers are increasing, deservedly .

[@quantumleap359]

Beautiful restoration and final checkout. Your work is superb Mark!

[@user-hi9xg8my4n]

Thank you for providing me with hours worth of entrainment. I’d rather watch your videos than the latest TV series!

[@StevieBGoode]

I just recently discovered your channel on random a couple months ago. I'm astounded by your knowledge and collection of machinery. I can only imagine how much all that equipment would cost in a lump sum. Keep up the good work!

[@soulsirius]

One of the most amazing teachers you are on KZbin. Thanks a lot for these wonderful instructive videos

[@BokBarber]

For reference, the KA-405 was on the "budget" end of Kenwood's integrated amps in 1979/80, and it's still an extremely sold piece of kit.

[@ryzentevfik]

Man, there is only one smiling person in the world who does this job so well and that is you. Every time you take us to the magical world of the 80s and 90s. Thank you. 👏🏻

[@bhopale1]

It’s always a treat to watch your videos and I always say craftsmanship at it’s best

[@TheBudgie29]

Another great job Mark, on a wonderful Vintage Amp. Can't wait for the next one to drop.

[@johnwalker6752]

Mark is a natural in front of the camera love this channel who ever thought watching electronics being fixed could cheer u up

[@capelhanbury-tenison1288]

Hi Mark, a great film and wonderful service. I'm so looking forward to putting it through its paces again soon.

[@joseportela205]

Thank you for your great videos. It is a pleasure invest my time on them!

[@DJWarlock-qd4ls]

I can even smell the welding... Thanks for sharing your detailed work

[@admiralhipowa7158]

Mark is a master craftsmen, that amp is a beauty.

[@TheWeepingCorpse]

Never stop being you, you are brilliant.

[@NivagSwerdna]

I like the fact you actually test the caps rather than wantonly replacing everything.

[@remcovantriest4357]

Thanks a lot for explanation on the load resistor contraption appreciated Mark 🙏🙏

[@Throtmanni]

It was the cleanest and most professional work I have ever seen. congratulations.

[@geekbot5000]

Thank God you posted again, I felt lost without you.

[@robwatkins1547]

Thank you Mark for another brilliant video, your attention to detail is second to none and it's nice to see a thorough job on all the work you do. Please can I add that who ever keeps messaging me every time I comment I will not text to anyone, I am not interested and if anyone else receives a message, just ignore it, it's possibly a scam.

[@gunnarliljas8459]

Quality stuff. Both what you're doing and the amp.

[@iantyler4045]

You certainly go the extra mile by putting all the pots and switches in the ultrasonic bath. Very thorough. For bent over pins I use desoldering braid to wick the solder away. Great video.

[@smarthub56]

who has knowledge of every electronic tool infact mark is a knowledgeable mechanic.

[@apislapis]

What a great looking amp Mr Wood is! Still don't understand all that you do but it's great to watch.

[@butcharmstrong9645]

I so enjoy all of your videos. I binged watched all of them in a few weeks so I am glad to see that you're putting some new one up! BTW, hello from America!

[@snapcracklenpop821]

Thanks. I'm learning a lot from watching your videos. You are a great teacher on top of your obvious expertise.

[@joefarr3304]

I look forward to your videos and really enjoy them. I'm not an audio electronics guy and pick up so many little hits and tips - throwing a square wave into an amplifier to help test the tone controls for example. Thanks for making these.

[@iracema1]

So much fun to watch your videos! I would much rather have vintage than new equipment!

[@rodneydelaney9227]

Great insightful channel, full of knowledge. Love it Mark 👍

[@geyerking]

Really impressive work, Mark. And really entertaining. Please more of it.

[@MattTester]

It always makes me nervous now when you spray a front panel with cleaner! Great to see quality components lasting, a really nice amp that I quite fancy myself.

[@johnmarchington3146]

Nice one, Mark. Another excellent job over and above what a lot of other servicemen would do, such as measuring the ESR of electrolytics and replacing the ones that measure a little on the high side. Also all the ultrasonic cleaning you do. Top notch.

[@ashleycox432]

Top work as always Mark.

[@davesawyer497]

Thanks for another great fix. I've watched a lot of your videos and they are all great. The other day I was working on a job and getting frustrated due to lack of progress, when I thought to myself to be more like Mark. Relax, Chill out, add an "Oh well" in there. It worked! :)

[@andyh5224]

Hi Mark. First one of your videos I’ve watched. You have very impressive skills and great delivery. 👍 The reason I pressed play was that my Dad, rest his soul, had this same amp as part of a separates system in a wooden stand. I remember being mesmerised as a little boy by the little light that shone up onto the metallic squares on the side of the record turntable as it spun around.😊

[@damianbutterworth2434]

You seem so happy when things are broken lol.

[@Ivorbiggin]

I tell you what Mark ……your thorough a lot of people wouldn’t go that far …..anyway hats off to you well done 👍 New subscriber

[@paulwooller4524]

Love watching your videos - makes repairing some sad objects fun👍🏻👍🏻🤗🤗

[@jaydub8085]

Your videos make me so happy! You appear like you're possibly the nicest man I've never met! Keep it up, and thank you KZbin algrorithm! I'm so happy I found this channel!!!!

[@dagreatstoney.5869]

Fantastic job, you have a gift to make very complicated work, look doable and actually enjoyable 👍

[@RSCuber]

This is one of my new favorite channels and I'm glad to see you getting views and subs. Very well deserved. My favorite thing to watch while I'm working on stuff myself!

[@robertcobb9026]

Brilliant chanel. A joy to watch please keep making the video's Many Thanks Bob from Ashford Kent

[@UKDrew]

Awesome as Always...Really enjoyed this one.thank you

[@wolfmon9]

Great video's Mark love watching your stuff and your from my part of the UK.

[@boredwithusernames]

Thoroughly enjoyed this one Mark, keep 'em coming ;) 👍

[@andrewstewart8704]

Another top notch repair Mark!

[@davidrobertson1980]

Kenwood quality of course, great to see another one of these still in service. I still have my own Japanese *amps* from 1976, only had a couple of issues like accidentally burning out the power supplies in two of them overdriving far too long, guess they weren't really meant for mobile disco use lol

[@kevinisaac9139]

Brilliant job Mark you are very thorough and really interesting 👍

[@PhonoDirect]

Recently I have restored two identical Kenwood KA-501 from roughly the same period. The same story, no bias trim pots, only pots for the VU meters.

[@d_j_duane]

Hello, These days you don't find much technicians that do these types of devices any more (Where I am at least). I would really like to have some like you nearby to fix some of my old HiFi equipment. I just found my old JVC VN-300 1975 (I think)… And theirs no one to fix it... Great job in refurbishing these equipment's as these were made with quality and longevity in mind...

[@NickT6630]

Excellent video!!! You can tell they made much better electrolytic capacitors in the old days.

[@henriktoth56]

And most importantly those were not stressed by switching mode power supply, which is a killer of capacitors in its circuit.

[@ray-charc3131]

​@henriktoth56 I lately find that contact plates with batteries easily go oxidation with the growth of brownish or greenish stuff( depending on metal or copper contact plates it used), they happened on small handheld led lamp type torch and rechargeable battery handheld drill. I think the inside buck switching mode circuit causes them. I take out the batteries to completely disconnecting the circuitry after the use, the problem vanished

[@butterfliesandtape]

the solder vacuum is so relaxing to watch. nice nozzle cleaning. that's a tasty looking amp. love the simple three inputs.

[@Toytowner]

I had one. They were mint till the switches went noisy...

[@mollyfilms]

Really nice to come across someone you respect, is an expert in his field and explains exactly what’s going on. Makes watching this a good feel rather than a lot on YT these days which is total trash.

[@Jammerk40]

Very nice work! Ready to play for another 20 to 30 yrs

[@bussypaul7326]

Hi Mark! Good to see you again! Eagerly waiting for the next! Love from India!

[@magentaline]

Thank you for the great videos! I like the new shop.

[@mlprd]

I used to have this amp, it was incredible.

[@kerrygleeson4409]

Fantastic work Mark great channel 🦘

[@fluke196c]

Made my day! Sharter video and Mend it Mark!

[@Trucam2020]

Excellent video as usual. Thanks 👍

[@marktubeie07]

Always a pleasure Mark, nice one mate !

[@knifeswitch5973]

The “look” with the grounding rings, priceless. I know it very very well.

[@roncarter5532]

What a lovely bit of kit. I do like silver hi fi equipment, even better when it has VU meters.

[@marcparsons1726]

That was a proper education! Beautiful Kenwood Amplifier.

[@Alan8889991]

Dr. Mark, great job , as always, gretings from Croatia....

[@schummiehugo]

fantastic job happyman !

[@darrenwendell1723]

Great service as always.

[@bouser210]

I got the same amplifier for 5 dollars . A lot of hissing sounds and speaker connections work when they want. Great video.

[@artifactingreality]

I just found your channel. I like your style. I have subscribed

[@Timothycan]

Great job, very thorough. Only thing: I've had two amps faulty, one Denon and one Kenwood (a later one) that had intermittent faults, that of one channel occasionally failing. Turned out to be dirty contacts on the speaker protection relays. I note you didn't clean or replace the relay - those faults can be (as mine were) very intermittent, only showing up occasionally. I don't know how common that fault is, only that I've seen it twice now!

[@robinsutcliffe-video_art]

Good service again! At 25:21 in case it's not known - to test the EQ needs a Square wave, because EQing has zero effect on a Sine wave.

[@andymouse]

Bass will have an effect on a 100 Hz sine wave of course etc but the square wave is quicker.

[@robinsutcliffe-video_art]

@@andymouse true it will affect some frequencies indeed

[@GuyFowler]

Zen and the art of electronics maintenance

[@hazemal-najjar4834]

really i feel happy when i am watching your videos its really great and your knowlage 100% great keep going BOSS

[@nicksmith4507]

Nice amp, great video as always.

[@dustonsmoot8103]

Nice work man.

[@LockdownElectronics]

Excellent as always!

[@brianhoskins1979]

You can't beat that old HP rack mount test gear. Really nice they are. I've always wanted an 8903 Audio Analyser but not managed to get there so far and, to be fair, I wouldn't use one enough to justify it.

[@hungvanpham146]

I love your show so professionalism

[@russax1373]

Lovely Amplifier and a great video

[@paulmichaelfreedman8334]

I use Kontakt K60 for pots and switches. Always a great result and also very good lubricant.

[@3rdandlong]

Loved the old Kenwood Amps. Powerful, with excellent audio quality. Think I saw one in a thrift store recently. Guessing someone got rid of it because it won't work. But from my previous experience, I never went wrong with a Kenwood.

[@hernanmartinez1591]

I would really like a descriptive video of your lab. I fell in love with the HP multimeter! 😊. Greetings!!!

[@leemparry]

Top job, as always! I don't suppose you've got any plans/schematics for that ESR meter? I definitely need one for the shop!

[@bobert4522]

Search online, I can guarantee it came out of an old electronics mag 👍🏻

[@fredzwijnenberg5361]

Please share the schematic Mark...i need it to..its works good..😁👍👍

[@richardhack9830]

I was nicely surprised to see Mark using his ESR meter - testing electrolytical capacitors in circuit ! A Google search (simple 100kHz ESR meter) quickly took me to good & efficient schematics, using basic TL082s. Thanks again Mark, pls keep up the good work ! - No need to guess what my next "project" will be... 😅

[@decibel_tastic2869]

The one I built was by an Italian guy, I used the entirety of a cheap moving coil voltmeter as the display. It's indicative really. Be aware, discharge large caps pre-test, although the design has a couple of diodes reversed across the probes.

[@richardhack9830]

@@decibel_tastic2869 Hello, deciBel_tastic. I have a minor question about your ESR meter. There's always a zero adjustment in the schematic diagrams I found. Is it necessary to readjust at zero regularly, or is it a "set-and-forget" adjustment? Mark had build his adjustment with an external knob. My aim is to use a walwart SMPS power supply (+ some extra capacitor to smooth it down). Thanks in advance for sharing your experience... 😃

[@microteche]

Old school servicing done right enjoyed the video

[@dgedi78]

Working great! The soy sauce in your ultrasonic cleaner certainly helped 🤭

[@DavidFRhodes]

Enjoy your videos Mark. i think i've seen all but one of them now. You're a really good teacher..have you thought of maybe doing some fundamentals videos? Not formulas, but how to use a scope and whatnot. I was EE in school for a bit, but have a huge gap between theory and troubleshooting and soldering. thanks

[@j.harbottle8928]

Yeah, good idea David, Mark's a good teacher ! Love these vids , like the ol Techmoan's !

[@BoBB2000]

Plenty of that already on youtube

[@teslasapple]

Nice and smooth as usual

[@2626sylver2626]

Beautiful job 👏 👌

[@SergZak2023]

Mark's paper towels can double as blue notebook paper...or vise versa. Good job on the service, Mark!

[@standishgeezer]

Superb job!

[@fillo1971]

Mi fanno sorridere certi commenti, fai li fai qui controlla là, ma invece di polemizzare fate un video riparazione anche voi e vediamo che sapete fare e con che competenze. Mike te l'ho già scritto per me sei un tecnico veramente professionale, oltre ad avere tanta serenità la trasmetti anche. Grazie Mike 👍🏻💪🏻💯

[@daveg8htfadlibaudio250]

Quality video Mark as always, attention to detail spot on. Have you any valve stuff to do in the pipeline as I think you would do it equally fantastic in your informative way, and it would take me back to the 70's in my head when I built quite a few single ended and push pull amps for my disco when I was still at school. Keep up the good work. Regards Dave. 😀

[@telegraphhill803]

I also tried ultrasonic cleaning in the past but now to mechanical cleaning of contacts with fibre brush and contact grease at the end. Needs more time but I give an guarantee of 3 years for my work.

[@butterfliesandtape]

interesting to see what bass and treble do in that waveform you showed us on the monitor, loudness too! very interesting!! lovely amp!

[@rongeernaert1208]

Nice tech repair of this Kenwood amp !

[@vintage_audio_INDIA_7777]

Appreciate ✌️