Audio Signal Generator Restoration EICO 377

[@MrCarlsonsLab]

To learn about electronics in a different and "very effective" way, check out my Patreon electronics course here: www.patreon.com/MrCarlsonsLab

[@tylerufen]

Mr Carlson's Lab I'm curious where you start it at... do you assume prior knowledge (or prior failure) at all?

[@slainesmith]

Hi Paul, recently joined your patreon page, how do I PM you? I am new to this sort of stuff

[@MrCarlsonsLab]

What is your name there Chris? I will PM you to make this easy, then you can just PM back to that original PM..This will get you started.

[@slainesmith]

Hi, my screen name is chris johnstone. Look forward to hearing from you.

[@MrCarlsonsLab]

PM sent on Patreon.

[@SeattlePioneer]

This video is BETTER than being an apprentice electronics technician working at the elbow of a master. Thank you!

[@sirmeowcelot]

Mr Carlson's videos should be used as the standard for the education on this area.

[@cj-de2eb]

“No big deal, if the thing doesn’t work, we’ll just make it work… It really doesn’t have a choice.” I like that attitude. :-)

[@williambock1821]

I usually go with, “If it doesn’t work, we’ll turn it into a guitar amp.” 🤘

[@DrunkenUFOPilot]

If only that worked on software!

[@erin19030]

Thats confidence based on experience.

[@MrGigi-dz9cv]

It was made by human hands, we should be able to make it work.

[@KE8UYV]

After watching this video last friday, i bought the cleanest (and cheapest!) Eico 324 on ebay, and went through it and replaced all out of spec parts, rebuilt the power section, checked alignment, and am now cleaning up the enclosure. I think ill be doing the same witha model 377 next! Thanks, Mr. Carlson!

[@mearslab]

This is the quintessential Mr. Carlson's Lab video, love it!

[@Darylvb]

I do not understand why anyone could possibly dislike your videos.

[@johnhicks735]

I'm glad that there are people like you still out there fixing.& Repairing units.& Older equipment like that always now days to work as it was intended to do.,or it's purpose it was made for.

[@Thomasp671]

I love that blue old fashion look.... easy to read and not to complicated. Love it Paul !!

[@walterstroup7557]

Thanks again for your video on restoring the very early Eico 377 Signal generator. What a beautiful job you did on that sig gen…. I really appreciate the fact that you emphasize safety when working around high voltage and expressing that some early test equipment can be dangerous to use… The most enjoyable part of the video is when you totally went over the schematic and explained the circuit design and how it works… It brings back memories from when I was 13 and built many of the Eico kits which I still use now at the age of 76… Thanks again I'm a new fan …. Walter

[@bgdavenport]

My father was an electronics specialist in the 50s/60s. At a time when when 8 or 9 out of ten American households had one TV, I had my own that my father built from spare parts from the TV repair shop where he worked part time. He was a USAF electronics specialist working on air-to-ground and ground-to-ground missiles back then. Your voluminous knowledge, skill set, and attention to detail and safety remind me of him.

[@cwgreenley]

The knowledge in these videos is a treasure to mankind. These should be archived in the library of congress for future generations.

[@MrCarlsonsLab]

Thanks for your kind words Chris!

[@rtw8972]

Mr Carlson, I have watched many of your videos concerning tube radios and tube test equipment. Your analysis of the problems is spot on because I grew up with tube technology and I attended Valparaiso technical institute in Indiana in the 70’s. At 16 I was a certified repair technician in the state of Indiana. For a younger man I am surprised at the extent of your knowledge. Keep up the good work. Ronald Wisniewski

[@MrCarlsonsLab]

Thanks for your kind feedback Ronald!

[@rubusroo68]

one hour & 38 of pure genius. I leave after watching your content feeling a wee bit smarter! Thank You Mr Carlson

[@hollihobbi1230]

I have no idea what you are talking about, but for some reason your voice, knowledge, and genuine interest kept me hooked the entire time. I don't regret a single minute.

[@MrCarlsonsLab]

Thanks for your kind comment Holli.

[@toma5153]

Thanks for taking the time to warn folks about the dangers of cadmium. An excellent restoration. I wish you did a comparison of the frequency output on the different scales, checked by the frequency counter. Also, your discussions about electronic design using the schematic are always excellent. Learn something new on every video.

[@raymondheath7668]

Always love your in depth, but elementary explanations on the circuits. Gives amatures as well as old timers a better understanding

[@KenPaisley]

We'll make it work, it doesn't have a choice. That's why I love Mr. Carlson's lab! You have taught me so much in my spare time, I can't thank you enough.

[@kubiedubie]

The amount of technical detail that I learn from your videos absolutely blows away anything that I have learned in any of the university level electronics courses that I have ever taken. Awesome work!

[@MrCarlsonsLab]

Thanks for your feedback Jake!

[@BruceNitroxpro]

@@MrCarlsonsLab , It helps that your business IS electronics... and it shows.

[@DuggTO]

I'm pretty sure my dad had one of these Eico generators. Nice to see one restored. THX Mr. Carlson

[@bryancunningham1095]

Mr C. I think your right on the black color on the cadmium plated chassis, some older transformers used a paper wrap for insulating that contained sulfur compounds, when the transformer blew or got hot the sulfur combined with the cadmium to form cadmium sulfate which will cause it to blacken. Your videos are great and i learn something each time.

[@chesterkuzia7286]

High voltage is very exciting to work with! Keeps you on your toes!

[@ancienttech4636]

Or knocks you on your ass! 😂

[@kharakim]

Another one of Paul's peerless presentations. Anyone who can't learn continuously in this classroom, simply can't learn. The wonder is that so much education can be so stimulating and entertaining.

[@williambock1821]

Your knowledge never ceases to amaze me. “A car battery sitting next to it…” WHO ELSE would instantly know that? 🙌 Hehe,I also liked ,”The only way to get this stuff off is to remove it” 😁

[@erin19030]

In the Army most of our radio equipment was battery operated by 2 x 12 volt batteries. In the shop we had a vented area under a bench. The batteries sat on a wooden pallet, not on concrete.venting was a must, now you can see why. My friend owns a plating company. I set him up with a computer in the office. So he decides it would make better sense to have it in the shop for time card record keeping . It lasted two months. He called me to fix it under warranty. When I got it in my shop Nd opened it up, the sulphuric acid had totally destroyed the circuit boards. We ended up in small claims court and the judge laughed at him, awarding me the judgement. Common sense says fumes are fumes!

[@mikeharnett2410]

SERIOUSLY cannot wait for the CCLT, the Carlson Capacitor Leakage Tester. Many thank you's in advance Paul.

[@cliftonmeager8101]

Hi. I just found this channel and one of the first things I watched was the work on all the old test equipment. It takes me back to when I just got into electronics. I repaired TVs and radios when tubes were a big thing. Great videos.

[@retrobrw919]

The oscillator circuit in this piece really is still in use! We literally just talked about this type of oscillator in my college op-amp course over the past week! Great restoration as always.

[@wingshooter1967]

Not exactly sure why I enjoy watching your channel so much but I do very much enjoy it! I used to do a lot of troubleshooting for the 20 years I was employed as an licensed aircraft mechanic A&P.

[@user-qm7nw7vd5s]

Brings back childhood memories! I worked on the silver version, but still tubes, handed down from my much older brother. He got it brand new from the original Radio Shack in Boston; not a little retail outlet, but the real thing, a big sprawling hub of activity. Mine was shiny new, and with some tweaking I got it to work fine!

[@BruceBoschek]

Thanks very much. I enjoyed this one particularly since I built a 377 back in the late 1950s when I was a teenager. I used it for years and it never failed me.

[@aopstoar4842]

I have now worked up the courage to repair an old Electrolux Assistent food processor from the seventies. Old capacitors and resistors just the like the ones in Mr Carlsons videos. After a couple of years rest it was used to make bread dough this week but it soon smelled like something was burning inside. Metal capacitor from Denmark is a nice detail. I did not know they had been in the business. Thank you for another video. Principles applied and explained and frequency ranges revisited.

[@erin19030]

Thanks Mr. “C” , your theory description was spot on. Even I learned something and Ive been in the Biz since 1960.

[@benzcrazy]

Thank you for all the information ,these videos are so much help ,its refreshing many things my father taught me ,He was a radio and tv repairman as well as a IBM computer guy .

[@DanielMelendrezPhD]

I cracked laughing when you said: "Well, that's a good sign......wave". This is by far the cleanest and the most "attention to detail" channel on KZbin. Congrats, Paul!

[@MrCarlsonsLab]

Thanks for your kind comment Daniel!

[@gambini_modding]

Gotta love the passion you put on explaining the logics behind your work. KZbin´s algorithm has the custom of putting your videos when i am aspleep. I am learning electronics without even knowing!

[@Lesstroublesleeping]

As usual a cornucopia of information! I ALWAYS pick up a new trick or insight when I watch your videos - even if I've previously restored the same piece of equipment. I really liked your 'warning' not to reform caps. I recently ran into a gentleman at a local electronics shop who talked about reforming caps... I absolutely agree that there is no reason to reform with the current pricing on caps. I'm in my mid-fifties and semi-retired from high tech, but really feel now that I need to 'fully retire' so I can go onto Patreon and continue my education from your projects there! Another big thank you for all you've contributed to the field of electronics - both old and new!

[@MrCarlsonsLab]

You're very welcome!

[@Kettletrigger]

A restored old-time workbench? I couldn't resist...you got me with this one. I'm now a Patreon supporter.

[@MrCarlsonsLab]

Great, see you there!

[@philipdecatanzaro1822]

This is quite an extensive repair. I'm not sure i would have gone this far to get it operational. I just bought one of these and this vidwo will be really useful. I'm hoping to align many radios in my retirement. Thank you.

[@erin19030]

You blew my mind with the very clever way of removing the parts nest, from the chassis.

[@TheRadioShop]

Simply amazing Paul. I think you topped this one. The detail of the restoration was great. Sine.......wave, loved it!. Thanks for sharing your brilliance.

[@MrCarlsonsLab]

Thanks for stopping by Buddy!

[@kaa522]

Great restoration, your 377 was factory built, the tested date and the fact rivets were used on tube sockets would be the giveaway.. Most EICO test equipment I've ran across were kits, to say the quality of the build is erratic would be an understatement. In the late 50's my Father built an EICO 249 VTVM which I still have and use regularly on my bench to this day. This was the kind of gear I used when I was making my living servicing TV, radio and audio before I got my FCC license and started working on transmitters.

[@6A8G]

Hey Mr. Carlson, re. removing controls from the front, I had an old pair of needlenose pliers which no longer closed correctly. I ground the ends off & wrapped the ends in two layers of package tape. I use these modified pliers to remove the nuts on faceplates. This helps protect the faceplate from scrapes. Thank you very much for yet another very instructional video.

[@eecajledo8430]

@ 1:22:46 (If the thing does not work we will just make it work. It really does not have a choice.) That is such a positive go get em attitude you have about theses things Mr Carlson. Probably the reason your so successful in your career.

[@danielrine3103]

Mr. Carlson, very nice job, this test piece looks and operates like in the day... I just love vintage electronics, nicely done....

[@Stuartrusty]

A beautiful restoration job, a thorough and clean job on the chassis. Clearly someone who takes time and pride in his work. Thanks so much for sharing your experience and knowledge.

[@Maskddingo]

Cool! I found an EICO audio signal generator (later days) at goodwill a few years ago. I couldn't resist, but I haven't got around to fixing it up yet. This is some good inspiration, and guidance. Thanks!

[@skycarl]

Another great video. Thank you Paul. These are real packs of knowledge. and btw,,,, I want to also mention that anyone wanting to up there electronics game should seriously consider the Patreon program available here. It's truly a fantastic deal.

[@jabelsjabels]

More tubes = more better! Thanks for the outstanding video as always!

[@danielrine3103]

Mr. Carlson, I will be restoring an Eico 377 and this video is wonderful in that it will give me some ideas of what to do and how to do it. I have a schematic in front of me and as you go through the circuits I use my schematic to follow and this video helped me to understand this circuit. Thank you kindly for sharing this knowledge.

[@MrCarlsonsLab]

You're welcome Daniel!

[@erin19030]

Ive just restored one of these audio oscillators and it works very well. I made it a standard on my test bench.

[@codydowling1120]

It’s not even started yet and I can already extend gratitude for yet another great video. :)

[@kenhancock8931]

that's what she said!

[@codydowling1120]

😲 oh lort... you boys are not right...

[@poormanselectronicsbench2021]

@ 40:55 , we can see you added a new power cord (to assembly instruction original connections) , and @ 54:20 you state that an old electrolytic cap, if shorting out, can burn up your B+ and filament transformer, but, how about installing a properly rated fuse in this older equipment to protect it better from future component failures that may damage hard to obtain or irreplaceable components? Some of this old Eico, and Heathkit gear (and other manufacturer / models as well) , have no fusing on the primary line/mains side, but if you check similar newer models of the same types of equipment it was added over the years. If no fuse is added, that unfused line/mains circuit will feed your transformer, or in some AA5 configurations (with a solid state rectifier, the shorted filter capacitor/s,) all the current they can ask for until the smoke show is over. Granted, like you said, this is your device to do what you want with, but IMO checking for proper fusing, and adding it if it is not there, is a good practice to follow.

[@josephp.polnaszek9134]

Hello Paul, I just wanted to add that muriatic acid also works very nicely for removing galvanizing and cadmium from metal. I really enjoy your videos, you do an excellent job of it. Please don't ever stop. Joe n0usg

[@MrCarlsonsLab]

Thanks for your kind words Joseph!

[@coldfinger459sub0]

In my college trade school I’m taking electronics and my instructor just offered one of these to me because it’s been sitting on the shelves for decades collecting dust. I’m his only student who got tube fever and started building tube amplifiers so he’s been slowly offering me all the old electronics gears from the 1950s 60s now that I just seen this video I will start the restoration of this old piece of equipment in my class to show the other students. Thanks I will be joining your Patreon soon.

[@MrCarlsonsLab]

Hey, that's great. Sounds like you're the student that the others look up too.

[@Uncle_Buzz]

You always have the best sounding audio... I guess I should expect that. Loving and binging these videos. Cheers! NI7I

[@bigmac965]

"...stare deep into the magic eye." Love it! Thanks, Mr. Carlson!

[@MrCarlsonsLab]

You're welcome Mac!

[@betonmolenislol]

can't even have a drink in peace around _your_ videos anymore. that sine wave joke caused a wine wave from my nose. great content as always. there's more tube gear coming my way as well, i don't think i can hide behind the solid state any longer. i better become a patron.

[@jackallen6261]

Keeping everything together is a Brilliant idea! Why didn't I think of that! Thanks so much for your videos!

[@LJJKD1947]

Wonderful video, loved your schematic explanation of the 6SN7 square wave circuit portion.

[@hadireg]

Ton of knowledge in a single video!👍👌 Thanks Paul! I still feel the need to watch this video some more times!

[@DaruoshAghajaney]

Fantastic restoration video. When you opened the case and I saw the condition inside the unit, i said "Wow, it;s impossible...". I really enjoyed your technics and how you did the restoration steps in a very neat approach.

[@erin19030]

Once a month I would splurge with my spare cash and buy an EICO test equipment kit . EICO's business took a dive when it entered the home electronics field with radios, tuners and amplifiers. Their meat and potatoes potatoes was test equipment . These days i spend time restoring vintage EICO test gear. The 460 is on my bench right now.

[@thomasrice2888]

Should be at sea now but a bad accident and a broken back keeps me at home. Why not learn electronics when I’m able to sail I will have increased my electronics knowledge! Always a plus!

[@SDsailor7]

Beautiful work Mr Carlson just beautiful! big thumbs up!

[@MrCarlsonsLab]

Thanks Rob!

[@garybevis8691]

Hi Paul, great video again! My goodness that was a labor of love. You are fortunate to have access to the bead blaster, it is one of my favorite restoration tools. Very Sherlock Holmes of you to deduce the black corrosion on the Cad plating to attack from Sulphide from Lead Acid batteries. I have seen a yellow corrosion on Cad plated chassis before, but not black fortunately. I simply devour and delight at each and every new video here and on Patreon. I'm just finishing building my take on the Cap discharge device. I really enjoy your videos, brilliant engineering, and dry sense of humor. You truly are a treasure and I admire and appreciate EVERYTHING, you do. Sincerely, Gary Bevis

[@MrCarlsonsLab]

Thanks for taking the time to write Gary!

[@driverat8s]

My Dad had this one. Brings back memories.

[@johnparichuk8367]

I had to chuckle at your comment, "smoke generator"!. Throughout my 22 years in the Navy, I always referred to the initial power up of a repaired piece of equipment as the "smoke test".

[@bryanmcwhirter9945]

Thankyou. I have been following for sometime now and I appreciate your passion for the old gear, as we called it. I have some old Ieco and Heathkit gear and still use them, kind of a pack rat, and glad for it. Will be restoring my 1958 Quad audio amp, 2 mono blocks but a stereo preamp, all 220 of course. Don't believe there were actually marketed in north America at that time, but have the original Manuel with schematic. Thanks for the inspiration.Best to you!

[@berndb.5097]

Hi Paul, Eico did a verry good job to the faceplate design. They choose the collors that perfect matched to my eyes :-) I like that.... Thanks to you for bringing back gear like this to life. This was again a verry impressive video.

[@scotthettel949]

After watching so many of your video's with great interest I joined your Patreon course and look forward to learning a whole lot more to further my amateur radio hobby.

[@MrCarlsonsLab]

Great, see you there!

Just love it. And just cannot wait for the cap leak tester (parts already laying around) and the bench to get populated and in use !

[@matthewh4550]

Hi Paul, another tour de force! At this point I've watched pretty much all of your past videos and I'm a subscriber to your Patreon course which is great by the way. I always learn something from these fantastic videos - you mentioned somewhere that you've got some old TV sets for future videos and I really can't wait to see one of those get the Carlson treatment in the lab. Keep up the good work, you're a real gem and I hope you realise how much a lot of your viewers must really appreciate what you're sharing here with us.

[@MrCarlsonsLab]

Thanks for your kind feedback Dennis!

[@kei_otake]

It's so interesting to see these older videos of you using the Heathkit before you began using your Low Voltage Capacitor Checker! This is my first time commenting, have loved your videos for the past year now. Thank you for your passion and dedication!

[@deadfreightwest5956]

27:00 - Good point. One common cleaner NEVER to use on aluminum is Simple Green. It will attack it over time, and you can never quite get it off. Paint won't stick. Beautiful restoration, BTW.

[@rich1051414]

Unless you want frosted white aluminum that is. Not a bad look... if you want it. A lot of 'degreasers' will attack aluminum. In food service, there's this 'generic' purple degreaser that will turn aluminum white instantly. A single drop and there's a permanent white dot on an aluminum surface. Oh, and you are not getting it off. It is corroded aluminum deep into the surface. You would have to grind it off, completely resurface the aluminum. I don't know about paint sticking or not, I would have thought the inverse would be true, due to the pitting.

[@neptun733]

if you like to paint aluminum you need to have a primer for aluminum.

[@thermionicemission6355]

Cute cat!

[@MichiganPeatMoss]

That epic turning point video where the capacitor tester was announced. :) It's still on my list to build - late 2021.

[@johnthegrim8602]

What else can one say? Perfect. Thank you Paul, you are the "Mr Rogers" of the electronic engineering world. I plan to sign up for your patreon acct. very soon.

[@MrCarlsonsLab]

Thanks for your kind comment John!

[@harrystevens3885]

Another wonderful restoration and the 1:38 just flies buy, professional from start to finish and simply the best thing on KZbin for me ...FANTASTIC VIEWING!!

[@MrCarlsonsLab]

Thanks Harry!

[@erin19030]

I was a working tech in my day starting with Radio -Tv-Phono repair. From that I went into electronics research, design and teaching. Then i ended my work life teaching electronics at a major east coast college. Ten years into my retirement life I find myself restoring vintage electronics test equipment and watching Mr. Carlson.

[@harryhall5092]

I have a 377 that has been sitting around and always wanted to go through it. I wondered on how accurate it was and the trueness of the sine and square waves. your video helped me decide to go ahead with it. Mine is a much later one (silver face) inside it says May 4 1971. The circuit looks the same with minor differences with the variable cap being a two gang. I noticed that yours was a 4 gang with the two sections tied together. The sine/square wave is a slide switch instead of the rotary type. This unit is nice and clean with excellent front face. Thanks for the video, I really enjoyed watching and I'll be checking resistors and changing all the caps and cleaning all the controls and switches, looks like a decent piece for my work!

[@MrCarlsonsLab]

Great! If you restore it, keep me posted.

[@erin19030]

Ive got one of these units on my bench right now. I finished the re- cap process. Next up I tested the R’s and replace anything off value. You answered my Q about the shaft coupler on the Freq. control. I forgot about that theory over the years. Thanks! My only problem occurs ar the top band. If I adjust and calibrate 100 Kilohz and tracking is good the square wave looses its integrity and looks more like a sine wave. The frequency begins to go ooff cal.around 200 Khz and the end of top range is 250Khz. The 6SN7 is the original EICO tube, it tests good in my EICO tube tester. All the components in the square wave shaper test good and Caps were replaced. I did not use a 1k ohm resister across the output when I tested it

[@arndbeckmann825]

Hi Paul, just love the restoration of the Eico 377.

[@MrCarlsonsLab]

Thanks Arnd!

[@erin19030]

Love that baked on blue paint application!

[@erin19030]

Nice job on the chassis breakdown and treatment. Its much farther than I could go. When I worked in industry I had access to a machine shop and could do the blasting.

[@montygore]

Beautiful job.

[@jimmyg.9781]

Thanks for the vid. The blue EICO stuff is my favorite. I enjoy all of your restoration vids.

[@boulder89984]

What are the odds that the person putting this together saw it still running after all these years? Can't replace quality and pride at any price. Nice rework Mr C.

[@DonDegidio]

Hi Paul, Absolutely amazing restoration. Thanks for going through the time making the video. Enjoyed it thoroughly. Took me a couple of sittings only because my dad's health required my help, otherwise I would have been riveted watching the monitor. Two thumbs up is not enough. :-) 73 WB3BJU

[@bloguetronica]

A Wien bridge oscillator indeed. Recognized it the moment I saw the bulb. Another great restoration!

[@zyspan]

Same here - brought me back to college days 35 years ago.

[@BjornBlomstrand]

Thanks for a very instructive youtubeclipp. I have learned a lot of you. Bjorn

[@gregorythomas333]

My Grandpa, who taught me electronics very early, also taught me how to KISS. Keep It Simple Stupid! And how Paul leaves everything together until after re-installation is a great example of that little rule. I wish the original "Tested" markings were able to be left on...I love finding those while working on older equipment.

[@igvc1876]

ok the first sentence had me pause for a moment, not gona lie. nice one :)

[@Derrick6162]

I have a plain jane 377, recapped a couple years ago. Good generator. Nice job Mr. Carlson. 73

[@MrCarlsonsLab]

Thanks Derek!

[@billmartin1591]

Great, intense work, good as new plus

[@lelandclayton5462]

I got an RCA WA-44c I have been restoring. Had to change the dial tracking by attaching a knob to the dial face itself. I plan to toss on a BNC connector so I can use it with modern devices. Also old PCBs are a pain in the rear to remove old worn out parts from. I lifted three traces and had to use a jumper wire to repair the broken traces.

[@peteleoni9665]

This is a great general vintage resistor/capacitor tutorial for beginners. I feel the title should reflect that.

[@erin19030]

Ive got the silver case 377 with black numbering. Its the same works inside, some use the newer Noval based tubes. My inspection sticker is dated 1965. I love the blue baked on paint job of your 377. However I do believe the silver look is more space age looking. The antique radio repair bench in my little shop is all EICO equipment placed in a wall of silver pieces. I also have a Barker & Williams Audio Generator. The color scheme is a hammered powder Blue steel case. It made to Mil-Spec. I worked for B&W in 1961 and picked it up upon severance. Yes , EICO did cheapen the construction of the 377 Audio Generator. The chassis and panel metal are made of a Cheaper,.and thinner grade of brushed Aluminum. The 4 ganged variable tuning cap was reduced from a 4 gang section to a 2 gang sections.

[@Moosetraks21]

Really beautiful piece of gear. I love the blue and red color scheme.

[@bergarteric5713]

Good morning Mr : I love your magic hand ( and your mind !!! ) i'm totaly in a dream when you work and your explaination is a cool moment for my brain !!! thanks Mr for your vidéo and your explications !!!! I love your chanel because i'm leaning many many thing for my passion .. Thanks for the share !!! god bless you and your family ... Sorry for my gramatical but i'm living in France and i'm leaning American langage myself ..

[@CliveChamberlain946]

Hi Paul, I don't know how orthodox you are on restorations, but adding a neatly placed BNC jack may not be a bad idea (as long it as it doesn't clash with the "look" of the panel). I would add two.. the 2nd would be a 50-ohm square wave output driven from a single 74HC14 fed from a 7805 running off the heater supply, likely. The tiny dead-bug circuit shown by W2AEW (see: TDR using an oscilloscope ) is soldered to the back of the BNC so it's close to the jack and offers 2ns edge rise time, making this good-looking old-timer able to keep up to specs and signal purity of any modern equipment.. OK, that's my 2-cents for the day.

[@mikemiller4838]

Love the videos. Am now a patreon supporter. My number 1 fav channel on the tube. Keep it up. Thanks a bunch.

[@MrCarlsonsLab]

Great Mike, Lot's more video's there too!

[@QARepair]

😂30 years ago when I was young boy that spider compo net in hands will be like scrap but in these days that's something - vintage. You are a very clever man 👍

[@drewsmith6066]

Cool video it looks brand new now..great fix...the guys a Wizard.

[@nikmilosevic1696]

Another fantastic restoration and great video. Cant wait to see your capacitor checker design.

[@MrCarlsonsLab]

Thanks Nic!