Amp Repair And Restoration - Kay Model K550

Tons of information to help you repair and restore amplifiers! Lots of tips and techniques that you won't find anywhere else. In-depth component testing and more! Click the SHOW MORE tab below for links.
To learn electronics in a very different and effective way, and gain access to Mr Carlson's personal designs and inventions, visit the Mr Carlson's Lab Patreon page here: / mrcarlsonslab
Capacitor video displaying ceramic disc noise (and more) Here: • Which Capacitor Do I U...
#learnelectronics #restorationvideos #repairvideos

[@MrCarlsonsLab]

To learn electronics in a very different and effective way, and gain access to Mr Carlson's personal designs and inventions, visit the Mr Carlson's Lab Patreon page here: www.patreon.com/MrCarlsonsLab

[@michaelraymondellis6997]

Thank you!

[@MrCarlsonsLab]

@@michaelraymondellis6997 You're very welcome Michael.

[@welderfixer]

Mr. Carlson, I can only imagine your history of electronics knowledge. I'm in awe with every video I watch. I'm lucky to know the difference between a cap and resistor. Thank you for efforts on your videos.

[@Realroyrogers]

I wonder how much that cost? A very fine job!

[@emilycs8823]

I usually stay away from audio content because of all the pseudoscience and ridiculous claims people make. But it's nice seeing your input on these audio restorations with an actual basis in science, without the nonsense people inevidbly get into with capacitors, or whatever.

[@phuckodclown4389]

In my mind you are Doctor Carlson, a true master of electronics

[@L.o.u.i.s..]

The Professor.

[@billchavez8473]

Crazy! I know this is a bit old, but I was just thinking exactly that. Dr. Carlson. A master of electronics, and a master of explanation.

[@denislajoie63]

I was going to write the same thing in my comment and saw yours just before I posted. You are bang on!

[@blueseruser]

Amen, brother…….! He is. Truly extraordinary!

[@jessemontano762]

Yes. Prof. Carlson

[@jonnydotnet]

There are experts and then there is Mr Carlson. An order of magnitude greater than your "normal" expert!

[@practicalmedicine4359]

I recently got out of the hospital after over 4 months (COVID is no joke). My wife was aware of my enjoyment of your videos and had the nurses play them, as wel asEEVblog, and big Clive while I was unconscious in the ICU. I’m so glad to be able to enjoy them again. Thanks for the time and effort you put into these posts.

[@kharakim]

Your tip on how to check speaker polarity came just in the nick of time. Yesterday I repaired an old speaker with a new surround, and I had no idea how to determine the polarity, because the manufacturer didn't mark the contacts. At first I thought that, since I don't have any resistors, I wouldn't be able to do the check. But when you did it without the resistor, I went ahead and got a clear movement of the cone, apparently without any damage. Many thanks!

[@OzirisTechnologies]

I never comment on any of your videos, simply because I do not know what to say, but I think this is overdue, thank you very much for your quality content. I enjoy every single one of your videos, moreover, THANK YOU for not dividing them into 12 parts like everyone else. I have severe PTSD, Ham radios and electronics help me keep my mind busy, and watching your videos helped me deal with my condition due to your very relaxed approach. I love the effort you invest in the quality of your audio, I can feel a true HAM at work. What I would give to have an Elmer such as you. Please never stop making videos.

[@reg-net8956]

Mr Carlson's Lab is the best electronics show on the web!

[@sumduma55]

I have to second this assertion.

[@chrisa2735-h3z]

Big Clive is pretty amazing as well!

[@vinceotten129]

@@chrisa2735-h3z what’s “Big Clive”?

[@kahlid-ataya]

you are the most generous teacher

[@RadioWhisperer]

There are so many repair tricks in here it's fantastic. I never thought to check how noisy the resistors are with a signal tracer. I always went by condition and value, this will make my repairs much better, ty! That and I never thought about speaker phasing in a two or more speaker system. I'll never miss that one again. Im a patreon member and I need to start following there more closely. The library of information you have built up here is amazing. Thank you for passing along this treasure trove of knowledge and practical experience! I have a EE degree, but none of that education covered the practical things I've learned from you. Always learning, always growing, and you've made that easy to do, thank you!

[@welderfixer]

Paul, so glad to see a new video from you. Hope you and yours are well.

[@More_Row]

Thank you so much with providing us with such high quality repair and restorations here on KZbin for all to see.

[@smallenginedude71]

its honestly unbelievable that such high quality content is free on youtube.

[@lawrencefusco3096]

I attended the Connecticut school of electronics in the 1970s and learned everything from individual components to microprocessors which were new at the time and very simple compared to today. It was a great electronics course and I did very well at job I had at the phone company which I recently retired from. The thing is every time I see one of your videos I often wonder if I had a teacher as great as you how different my life would be! You are the best teacher I’ve ever heard I learn so much every time I watch a video and you are so inspirational it’s amazing! God bless you!

[@1959Berre]

After a hard day's work, watching this is the perfect relaxation. Pretty sure Uncle Doug is going to enjoy this one.

[@questionmark9684]

Absolutely! Exactly what I feel!

[@stevepuffery8918]

Thank you Mr. Carlson. For being the one and only tech I know of who recognizes the art and value of impierical design work that went into the things.

[@MrCarlsonsLab]

You are very welcome Steve.

[@matthiasmartin1975]

This was a very good one. The resistor noise demonstration was impressive and totally new to me, i only ever heard about that in theory - it is quite a different thing to have it actually demonstrated. I also loved how you showed how to not puncture the speaker membrane. It is this attention to detail that is unique to your videos. Most people would not even think it possible to explain things down to that level of detail. Most of us figure things like that out after some decades of tinkering, but having it taught right away from a master saves lots of time and frustration.

[@crescentmoon610]

I love when he does amplifier videos! Love watching the master at work.

[@ahedproductions]

It's really amazing how you get something on the bench and then take your time to tell the whole story in a timely and orderly fashion, clear cut and simple, laying back on basic electromagnetic and physical laws helping to put the whole restoration (or whatever you take on doing and filming it) in a much needed clear perspective. This is not only very professional, because all your content just is, but your teaching and tutoring skills really come as a surprise in this field. Most tech wizz staff will have a very difficult time to even socialize in any coherent way, let alone explain, teach and convey proper and useful knowledge and experience, while maintaining a very lively vibe along 90 minutes of video. Bravo, sir, and thank you for another great hour and a half, it got me immersed better than a favorite movie!

[@denislajoie63]

Hi,The level of detail you go to is beyond... No one of my teachers ever explained anything about the outside foil on caps! Thank you sooo much!

[@MrCarlsonsLab]

Glad it was helpful Denis!

[@PeterDyall-bn7ut]

It’s such a privilege to see these amazing restorations. Thank you.

[@robertenache8463]

A dry-wet solution in a single package. Must be a great amp. Thank you Mr. Carlson!

[@FluxCondenser]

I’ve said it before, nobody does it better than Mr. Carlson. Really enjoyed this and loved the demo of the noisy resistors. I actually bought one of those signal tracers based on your suggestion a while ago and like the noise test feature. I ran into quite a few noisy wire-wound resistors in an amp I restored a couple of years ago. I actually diagnosed the issue using Super Freeze electronics spray. So, similar to your heat test, except going the opposite direction with temperature. When operating the amp and spraying the problem resistors with Super Freeze, the amp instantly started playing properly and quietly. When removed from circuit and connected to an ohm meter, I could clearly demonstrate how the resistance of the problem resistors fell into their rated tolerance when sprayed with the coolant. And, as they warmed up again, slowly returned to much higher resistance. So, the expanding/contracting of the resistor not only created noise, but also changed the resistance. I ended up changing all of those wire-wounds. There’s a video of the Super-Freeze/Resistor demo on my channel if anyone is interested.

[@bparker86]

I could sit here and watch you repair/restore electronics all day everyday. You are a hell of a mentor thanks for the great lessons over the years Mr Carlson your awesome man😊

[@MrCarlsonsLab]

Thanks for your kind comment.

[@chokkan7]

I found an old Kay 703 a few years back; got it for a song, as it didn't work. After checking through the chassis, all the components were still to spec with the exception of the multi-stage filter cap. I left it in place, soldered in 3 elcos of the appropriate value, and she now works like a charm in all her 2Ws of glory. The topic of today's video is more involved than anything I'd have thought Kay ever contracted for (they didn't build their own amps); the Hammond reverb pan was a total surprise. My guess is that this little jewel had some tone in its day, and that the owner used spit, baling wire, duct tape, and whatever else was available to keep it working as long as he could.

[@goodun2974]

The Kay was probably made by Valco.

[@doctorjohn-burgtekie]

Mr. Carlson - I was hoping we would hear you doing some guitar shredding on this repaired amp, very nice video.

[@dave1135]

Me too, Mr Carlson can repair anything, but can he shred? Lol

[@johnwallace1729]

@@dave1135 We need to hear some Iron Maiden thru that vintage beauty

[@imantisocial3179]

+1 for shred

[@no_more_free_nicks]

+1 for shred

[@AnilKumar-vk9qs]

Phone number chahie

[@thomasmoore8142]

Paul, the best thing was checking the speaker phase before finishing the unit. Most repair folks would have waited on that and if the phase was wrong they would have botched the primary wiring to fix the issue, leaving the next technician scratching their head. Thanks as always! And your Patreon page is worth every penny too.

[@Wim37u]

As one speaker is the reverb you can still flip the phase in the reverb unit and in or out of phase may be more of a personal choice than with a real two speaker box.

[@jeroldlawrence5186]

Its me again. Just got a new sds1000x-e oscilloscope. A lot of bells and whistles that i don't understand yet. Learning something new everyday, thanks to you. Thank You !!

[@blockbertus]

It always amazes me how good your audio/voice sounds like when you speak into the microphone at the beginning. Warm, clear, no background noise... Kind of ASMR.

[@radioaktiv7841]

It's like he's in your speaker talking to you, stunning quality

[@Dallas-Rife-UDX-347-Tennessee]

I’m an idiot when it comes to the things you work on in your videos , but it’s always a pleasure seeing you work and hearing you explain things . You have a great channel and skill on a level most of us can’t comprehend. Keep up the good work , Merry Christmas to you and your family , see you next video

[@paulcilluffo]

Excellent video I realy like your way of explaining theory of operation thats the hardest info to gather from available sources thank you paul

[@MrCarlsonsLab]

Glad you liked it

[@paulcilluffo]

Yes Paul theory can never be over rated I am a retired Ford electronics tech the most over looked section in a repair manual is Description of Operation .I often times wondered how one could attempt to repair a failed system if he did not fully understand how it was intended to work .Again please don't stop short on the theory of operation because its a very nice touch thank you again. I also notice with every project in every video there is a beginning and a completed end to the project you never not fix the item or give up and the ending closer display is a finished repair .Some channels are all over the place with at the end of the video no completed repair or a part two or three or a failure to fix the item your channel has high standards and that it would seem to be part of your make up thank you for allowing the viewer to be a small part of the process by indorsement of your channel Paul from Michigan the Great Lakes State

[@cuteswan]

1:29:42 "Electronic tonalities" for the win! (…except for an Oscar, apparently). You did an amazing job bringing it back to life, the inside sounding (and looking) as gorgeous as you and the other fellow did with the outside. Thanks for bringing us along for the journey.

[@bradleyleben7785]

Great looking and great sounding amplifier. And you did a fine job teaching. I’m glad you brought us along on this restoration. Brad

[@laurigardner6227]

I am passionate about sound, and so seeing the science behind the sound through this restoration has been relaxing and generally wonderful.

[@montygore]

Hi Paul. I have been a guitarist all my life in many bands since late 70's. Years ago I have had bad shocks from amps and microphones. I am a testament to the probles. Thank God todays tech as yourself know the danger. Thank you for your videos.

[@apollorobb]

This capacitor is excellent a very high quality capacitor it tests perfect with a very sensitive tester .......Lets replace it lol.. Great Video Paul

[@KarenMichelleLane]

Where was the capacitor autopsy? We want to see the gluts ! LOL

[@chrisa2735-h3z]

I am especially impressed with the restoration of the case! It is very time period Correct!! Also I love when people leave the patina behind- it's showing how much it has "lived" so to speak.

[@gregneill4246]

Would've been nice to have seen the "hand drawn" schematic as an example of the genre.

[@ravage444]

I’ve watched several guitar amp repair channels on KZbin. It’s great to finally see someone competently repair an amp. From a fellow engineer, I learned more from this video than all other channels I’ve visited. You not only spared us of reckless and cringeworthy fumbling; but, you also excellently explain your process and reasoning. Top rate quality video!! Thank you for raising the bar higher.

[@gebular118]

Great format, great information, the best audio of any site on the net. Thanks for all the time you take!

[@user-qm7nw7vd5s]

FANTASTIC little gem of a channel!

[@MrCarlsonsLab]

Thank you kindly!

[@johnopalko5223]

Having repaired and restored a few Hammond organs in my time, I recognized that reverb as soon as you took the back off the cabinet. It brought back some good memories. Thanks.

[@GregoryMcLean]

And here I thought we were gonna see Mr. Carlson playing the guitar! ;)

[@questionmark9684]

I would like that.

[@greggaieck4119]

What a Kool amplifier

[@whstark]

Really like this video allot of interest and inside info. After 50 years. You are the Mr. Rogers and Mr. Wizard of antique radios. Remember Melting old transformers in a toaster oven to replace some if's .

[@salliemorrill2671]

That was fascinating tests on caps & resistors. Never knew that you could "listen " to a resistor. Thank you for taking the time to make this video. God bless.

[@MrCarlsonsLab]

Thanks Sallie!

[@jacktietjen3125]

I'm not a electronics person, but watching your video was very interesting. It gave me a better window of understanding how a amplifier works. Thank you.

[@ianbutler1983]

Jack, II think if you go back and look at one of Paul's videos called "how a tube works", you will understand a lot more about how old amps work. Ian

[@jacktietjen3125]

@@ianbutler1983 Thank you Ian. When I get the chance, I certainly will. Stay safe.

[@A100Hammond]

Thank you for this video! I learned SO MUCH about older components!

[@msaradio7455]

Cant tell you how much you've helped me in this field..thank you for taking the time to share your knowledge.

[@MrCarlsonsLab]

Glad to help!

[@pepesworld2995]

ripper video as always. man i could never remember all these old timey types of resistors & caps

[@HeliBenj]

This is some real A+ tier work you do Sir. Well done and thanks for sharing

[@milchormiraflor4764]

I can’t stop watching and admiring your videos Mr. Carlson! Thank you!

[@MrCarlsonsLab]

Glad you like them!

[@robertforbes7666]

That is so interesting about microphonic capacitors being an "effect" feature that adds to the personality of the amp!!

[@leonardpeters3266]

Really a nice restoration. Strange design. I did a similar restoration on a tube amp Leslie speaker and modified it to take a line input from the player's new Hammond keyboard and of course power on without having a Hammond B3 hooked up to it. It was hard to preserve the glued paperwork on the chassis and still refinish it. I replaced the bearings in the rotating drum. When I was removing the drum a wasps nest fell out (YIKES). It almost got me almost as excited as when I didn't discharge the filter caps in my Marshall 30 years ago. There's a mistake you'll only make once. Beautiful, thoughtful work as usual Mr. Carlson.

[@PaulinesPastimes]

My brain explosion for the day. Excellent. 👍

[@jpdad2004]

I know next-to-nothing about electronics, but always enjoy these and always learn something I can apply later! Thank you & keep the lessons coming.

[@otekrec]

Mad props for preserving the character of the amp by things like keeping the ceramic caps! 👍🏻

[@hestheMaster]

That was both fun and educational. Thanks Mr. C!

[@davidportch8837]

another terrific restoration Paul - super quality work and some great insights into components and design... many thanks

[@jdirolf]

So meticulous! What a labor of love. Thanks for sharing

[@markphilpot4981]

This was an involved video and you showed some effective troubleshooting as usual. Got it to be real quiet after that workout. Good job Mr Carlson! Stay safe mates!😊👍🏻😷

[@anandarochisha]

Good Job Mr. Carlson. The opening of the 1951 Sci-Fi flick "The Day the Earth Stood Still", pleasing vintage Sci Fi noises..

[@faxcapper]

Frost morning.....BIG mug of coffee and a Paul fixes something video. It doesn't get any better. :-)

[@RadioWhisperer]

Another great video as always, ty

[@jpalberthoward9]

You and my Grandpa would have gotten along famously. He was a World War One Vet, and he started building crystal sets in about 1914. He learned the Morse code by listening to ships out on Lake Michigan. This was before any commercial broadcasting existed. He was thorough and meticulous, same as you, and he taught me the fundamentals of all this at an early age. Watching you work reminds me a lot of him. He was a real good guy, and he could fix just about anything. That little amp is probably going to be a really first rate studio rat. Good ribbon and condenser mics will probably make it sound like God shouting from the mountain top.

[@exogarwinoputt4257]

This wasn't just a restoration. It was a renewal. Thanks, Mr.C

[@MrCarlsonsLab]

My Pleasure!

[@skfalpink123]

Absolutely mesmerizing!

[@fullwaverecked]

Thank you Mr. C! I'm still learning a lot from your excellent videos!

[@okinawajapan1]

Wonderful video. Love your teachings. Thank you for sharing this knowledge. It's rare to find it. Grateful. Please keep it coming!

[@malcolmhodgson7540]

Having seen how the amp was internally wired to the mains cord and the fact it was a non-polarised 2 pin plug, I have made a note NEVER to plug my guitar into anything old ever again!!!!! It’s a wonder your customer lived long enough to employ you!!!!! We learn so much from your videos.

[@RozsaAmplificationLLC]

Beautiful...restored! I love you, Mr. Carlson!! lol Great clip, as always.

[@billbrowning3021]

That's a very interesting characteristic of the ceramic caps. I've been an electrical engineer for 37 years and I tend to think I've seen it all...and then I watch your videos and learn something new nearly every time.

[@hakare4]

First Mr Carlson video where all original caps tests ok! Wasn't expecting that when first seeing the condition of the amp!

[@rondrew1]

Beautiful restoration as usual Paul.

[@Antony_Jenner]

Hey Paul. I am glad you mentioned the disk caps being microphonic and adding positive feedback to the sound of the amp. Also back in the days of 10 to 20% tolerance its far to say that every amp had, like you said it's own personality. Good work as usual.

[@charlottejet4338]

Another Carlson spectacular 🇨🇦🇬🇧

[@bradwilmot5066]

"you would need a steering wheel on the front of it to keep the thing on frequency"... - Thanks, now I have an image of a steering wheel on the front of my Kenwood TS-520 that isn't going to leave my head any time soon... :-)

[@MSSONGCHAU]

Thanks! Your videos are always well worth the time.

[@jasontwynn7356]

Always great info and a learning experience. I watch you're videos all the time. Great job 👍.

[@derkchurk5879]

Good ole Johnson/Nyquist noise, great demonstration!

[@jaykay67design]

Very interesting video - I am always amazed at how you can reproduce the function of old equipment and repair it 👍

[@zbaby82]

I would just throw away all worn out electrolytic capacitors. I wouldn't leave them in the amp. And I certainly wouldn't stuff them with new ones. And I've heard that a C or D battery is safer than using a 9-volt one for testing speaker polarity. I really enjoy your videos. This was an excellent restore.

[@nevillegoddard4966]

You're right Zac, a 1.5 volt battery doesn't need a resistor to test a speaker safely.

[@DrMurdercock]

The new toltex on the amp looks absolutely AMAZING. the chrome cab corners, the piping, fresh chromed handle. Amazing looking amp

[@brianwood5220]

Lovely job Paul. Someone will be delighted to receive this back.

[@theduckisok]

As an old tube guy, this was GREAT!

[@GeorgeWMays]

Mr. C, you are the coolest guy on KZbin. Thanks a bunch for this project. It is fascinating and much appreciated.

[@gonzow0815]

You Sir are my personal hero.

[@paulgraf4140]

Great video 👍, great repair/restoration 👍 as always!

[@Joe_HamRadioGuy]

Great restore. Nice looking amplifier im sure the customer is going to be very happy.

[@bryandowdey1779]

Excellent work Paul. Very nice job!

[@TheLuxkywalker]

Ain't gonna lie, I was kinda expecting Mr. Carlson to pull out a guitar and play the heaviest riff ever. Jokes aside, nice video, very educational.

[@MrCarlsonsLab]

Thanks Ciro!

[@TeslaTales59]

I like your observation and comments on the glass jewel pilot lamps. I have some red and green ones from way back.

[@titoher]

Excellent explanation again. Thank you.

[@acestudioscouk-Ace-G0ACE]

Great attention to detail, thanks.

[@sonnydixonvideo]

Beautiful work!

[@Zero_Ego]

Love Mr Carlson's fine attention to detail. Award of Excellence in Education.

[@johnsonlam]

Really learn a lot, wish I have the time to watch more.

[@tracyc7813]

I really enjoyed many of your videos but this one is my favorite thus far. I would have loved to hear someone playing guitar through that when it was done.

[@cBroadbo]

Exceptionally done!

[@farmerdave7965]

In modern equipment the transistor blows first to protect the fuse.

[@MrCarlsonsLab]

LOL, correct you are!

[@lokig8640]

Really like the full length video where you go into lots of detail

[@utubejeffo]

Learned something: it's not the SPRINGS that make the reverb, but the little pickups at the ends of the springs... the springs are like "diaphragms" in a microphone. Very nice! Thanks! Excellent as always.

[@gervaserybak6999]

outstanding video again !! I was just thinking about you two days ago. That I have not seen a new video for a time. Now we know what you were doing. Great trick on the resistor. The space sounds took me back to the movie "Forbidden Planet". Thanks for the time and effort you do for the videos and for us. I hope you and the family are safe and well.