Electronic Circuit Troubleshooting! The Fix Made Easy!

Let's diagnose and repair this circuit together! This is Part 6 of the GRR Series involving the RCA CR-88 Receiver. 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
Part 1: • 1946 Secret Listening ...
Part 2 here: • 1946 Radio Receiver Te...
Part 3 here: • Capacitors And Electro...
Part 4 here: • Receiver Restoration S...
Part 5 here: • Electrical Troubleshoo...
Part 7 here: • Find Intermittent Elec...
Part 8 here: • 1940's Radio Receiver ...
Part 9 here: • Restoration Adventure ...
Part 10 here: • RCA AR-88 And RCA CR-8...
Restoration finished: • Finished! Restored 194...
#restoration #electronics #repair

[@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

[@XPFTP]

the blocking caps confuse me.. i dont get how they pull the whatever there blocking to ground and not go past then str8 to b + ... maybe down road explain how signals travel on the wires .. or if you will the cars on a road .. i guess they act like traffic control cops but whats stoping the traffic and making it do what the traffic cop says to do .. confused? lol

[@SS0341]

😊 Q

[@SS0341]

Qq

[@brucejenner4800]

I enjoy watching Mr Carlsons Lab as well, he is a veritable genius! And I find it gratifying that he shows no hesitation in explaining everything in a straightforward way. He's such a clever man, I think he deserves a medal for what he does here.

[@sKraat528]

Absolutely love this channel, and I learn valuable chunks on every video

[@peterream9437]

Clever people can explain complicated things in a simpler way. We had similar from one of the specialists during the Government covid lockdown. He would do a televised Q and A session with the journalists. Made listening and learning fun, Just like Paul😊

[@expressmail9977]

I don't know how somebody is able to absorb, apply, and explain that kind of knowledge. I wish I had a special autistic power I just don't. Mr Carlson thank you for taking the time to show us. You are the true GOAT.

[@ammoalamo6485]

I was lucky to have bought a similar receiver way back in junior high about 65-66. It was fun to power it up at night and hear sounds from across the world. I think it was called Voice of America - powerful, sending to Eastern bloc countries. BBC was there, and many Morse code senders keying way too fast for me to understand. I should never have sold it, but with the power supply the unit was way over 50 pounds and I could not lug it from apartment to apartment during my twenties. Mr Carlson is the best. Funny thing - any pther YT I can set the speed to 1.5x and comprehend everything, but with Mr. Carlson 1.25x is the max for me. p.s. I taught a 4H marksmanship class for a couple of seasons. It was my first time being addressed as "Mr. Alamo" by a bunch of students. We addressed the students as Mr or Ms, and all the adults addressed each other as Mr, Mrs or Ms too. It's a good way to have an attentive and respectful group, with everyone using titles + last names.

[@Brian-yt8fu]

I think Mr Carlson was actually born a hundred years ago. He has an amazing amount of knowledge about electronics.

[@NoPegs]

Good morning and Happy Saint Patrick's Day! 🎉

[@MrCarlsonsLab]

Same to you!

[@anthonymccarthy4164]

Seeing these things is so nostalgic for me, my father's generation of technology. I love your channel.

[@JFirn86Q]

I get so excited when I hear you say "I'm gonna cram your head with info" or "you're gonna wanna take notes". Everyone hold - I'm watching something right now!

[@DarrenHughes-Hybrid]

I love this channel! I learn so much watching it and electronics have always been so fascinating!! Thank you Mr. Carlson!

[@guyh3403]

Despite the fact I know nothing much about electronics, it still is amazing to see you at work like this. So interesting! Thank you sir.

[@MrCarlsonsLab]

My pleasure!

[@jayguditis2102]

That BFO can reminds me of my final exam in my first AC Circuits class in engineering school. We had a mystery box with 6 terminals on it, we were given an oscillator, a VTVM, and an oscilloscope, and had to derive the circuit inside the mystery box. Good times.

[@oldavguywholovesRCA]

I had forgotten about that old marking for resistors. Great video Paul.

[@jrbird7571]

Just found this channel and after I saw those beautiful Tektronix scopes in that lab, the thought of repairing my 564B came to mind. I'm glad that I never got rid of it. It has the rolling stand and shelf. This motivates me to repair it.

[@terrym1065]

One more issue diagnosed and remedied, totally amazing you found it so quickly and fixed with a finger nail😉 This is the best electronics channel on YT period. There's some good engineers/technicians with YT channels but none compare with the quality, depth of expertise and explanatory dialog as yours Mr C. I've been enjoying your videos from years ago, actually binge watching until I'm cross eyed. Think it's time to Patreon! Great video, well produced and presented, thank you. 73

[@MrCarlsonsLab]

Thanks for your kind comment Terry!

[@tonyking9235]

YES 100 PERCENT

[@jaredkusner1137]

An exciting class today. I have learned to take my time and think clearly about circuit , Then we go rite to the problem. Some simple easy thinking. Thanks so much.

[@johnwest7993]

Having started working as a kid at a TV/radio repair-shop in 1962 I figure I know quite a bit about tube gear, but I watch your videos because you know more. Someone really taught you well. BTW, I made a heavy-duty Lazy Susan to hold my heavy gear to work on.

[@tonyvancampen-noaafederal2640]

If I had to make a guess, I suspect that the M notation for 1000 comes from Roman Numerals I = 1, V = 5, X = 10, L = 50, C = 100, M = 1000 so that we are in the year MMXXIII. At some point after these radios were designed and built industry standardized on our current engineering unit standardization scheme. Great video, thanks for putting these together.

[@jrkorman]

which is why you go to the hardware store and by 4 mil plastic! Latin "mille"

[@gfodale]

Greetings, and thank you. I was a tech in the 80's. (not an engineer) I also got my amateur tech license at that time. A long time ago, and I just recently decided to get my amateur license back. My target HF rig is the Yaesu FT-101B. It's what I used back then. Not as complex as the radios I repaired in the Marine Corps, but a solid workhorse of a transceiver, and in my comfort zone. Off and on, I have watched your videos. All of a sudden, your videos have become more relevant. (Who'da thunk it?) I have my first repair challenge, and I need to straighten the face plate, as it interferes with the dial on the VFO. I'll be getting the external VFO, as it will come in handy, and may make this radio usable ahead of the repair. ( The face plate is stout and will require some force, but not hammer and anvil force. Still figuring out how to use a hydraulic jack to 'finesse' it. ) I plan to buy the 'cheap' parts radios when they actually are cheap, and repair a few, that I can turn around and cover test equipment costs. (really tight budget here.) Anyway, thanks again for educating and entertaining at the same time.

[@hestheMaster]

Thanks for showing all the steps in learning about a BFO and how it works Paul. I noticed the non moving plate ( stator) below the bent one you fixed was also a little off as well as one on the other side. A little trick I learned a long time ago is to use a flat feeler gauge (for automotive use) to set an even gauge as I don't have long finger nails. As a teacher on YT you are the best as far as electronics is concerned.

[@DavidTipton101]

An easy fix Paul, you would have to wonder how it got bent and when. It could have been like that for years. I had an issue with a mica cap recently, I didn't think to pull it apart 😕 Good video Paul.

[@SN-1006]

I love the new pace on this channel. Quality is not traded for quantity that's for sure. I hope you're no too much stressed out, Paul. I can't say enough how much I've learned throughout the years here. Thanks Paul for all the effort 😘. Soundquality, illumination, content, all is very professional on this channel. I wish you a happy weekend, Paul. Much love from germany 😊.

[@MrCarlsonsLab]

I appreciate that!

[@leetucker9938]

Mr C on my TV , awesome

[@johnglielmi6428]

It is so very rare that Mica Caps go bad. It was good to see how a failed one performs for future comparisons.

[@welderfixer]

I can only imagine how intelligent the engineers who designed electronics in the 30s-40s-50s were. This radio may as well been from a planet more advanced than ours. Genius! Paul, I am always in awe of your skills, knowledge and experience. Thank you for sharing. If I could ever become proficient at electronics repair it would be too generous gift from the "man above". I change many expensive boards and I know there is only a couple dollars worth of bad parts on them. Saving board and my customers money would be great! Let alone being able to repair my own audio gear.

[@davidkatona7485]

You truly are very brilliant and knowledgeable. Thank you for explaining electronics in a clear and understandable way.

[@MrCarlsonsLab]

You are very welcome!

[@poivre22]

You are a master of your craft and a fantastic teacher. Thank you!

[@MrCarlsonsLab]

You are very welcome!

[@denisdespins1127]

Awesome info ! I had been wondering about these Mica's for YEARS. God Bless my Friend.

[@MrCarlsonsLab]

Thanks Denis!

[@freddienz]

That is the first SSB Tx i have heard in many years! Ahhh memories.

[@evaDrepuS]

I am still learning a lot of the basics, and am always up to watch you and Adrian from Adrian's Digital Basement work on stuff, as you both have a very good methodical approach to working on electronics of different types.

[@MrCarlsonsLab]

Thanks for your feedback David!

[@kahlid-ataya]

your videos makes me relaxed

[@W1RMD]

I've always said that I wish I had a doctor with this kind of dedication, confidence and knowledge.

[@christopherjbutler]

Always happy to see a new video from you sir!

[@MrCarlsonsLab]

I appreciate that!

[@jeffminnick5209]

Some exceptional fingernail work!!! Live it, have a great day Paul WD8JM

[@mikefinn2101]

Sure learned something new Paul great video but you set the gold standard in electronics learning. You're the best of the best. Loved watching

[@ariedekker7350]

Thanks Paul, for the topic, your time for this video. Once again it was great fun. On to the next episode. pe1krx

[@MarcelStrucker]

Your new lab is great to see!

[@althepal6818]

Very interesting as I refurbished my CR91 and the BFO was and still pretty weak. Now, I know what to look for.

[@nathkrupa3463]

Nice video Mr Carlson sir you are awesome ❤

[@RJB64RJB64]

Even if I never do any electronics repairs I do enjoy watching the process of diagnosing, fixing and improving older equipment. A suggestion for Mr. Carlson. On the testers you have designed could you possibly label the switches and LED's so we viewers could more easily follow your testing and commentary?

[@davido.hamilton3254]

I agree with your comment. There are plenty of engravers out there who engrave 'lamacoid material'. It looks more professional.

[@Go4Corvette]

Thanks for the great video. Seeing this brings back memories of when I was first learing electronics back in 1974. I ended up working on the first automotive computers with GM and loved the job. Take care, Mike

[@rl2109]

Nice video for troubleshooting! I liked the cap tester, too...! Gonna search your library to see if you made it... God bless ALL of us! WWG1WGA

[@hymermobiler]

Hoovered up the content of this one & waiting patiently for the next one. Thank you for sharing Mr Carlson!

[@clytle374]

Good video, I learned some stuff. Never ran across the M being used for kilo.

[@leradiodigiorgio-iu1edh]

A very performing receiver and fault finding on the bfo very accurate and not easy to repair congratulations always very interesting to follow you in the repairs you will learn a lot

[@bob_mosavo]

Thanks, Paul 😁

[@richardgoebel226]

Great way to start my Friday.

[@W1RMD]

This series has been great! I look forward to the product detector and BFO videos. The video quality is perfect. Please don't apologize for the adjusting of the camera for different shots. You do great camera work that really doesn't leave much room for improvement. Looks like you've got your lab working better than ever. Best regards and have a great weekend!

[@wagsman9999]

I can imagine a day when Mr. Carslon restores a 1940s receiver, and it starts receiving a 1940s broadcast. Right out of the Twilight Zone!!!

[@alanletterman]

Hopefully the knowledge you are placing into my brain will push out some of the useless garbage I no longer need. The solution was simple if you follow the diagnosing process carefully. Thanks for the video!

[@sootydave1]

Paul, you have done it again. excellent video and instruction. Now on to the next one.....

[@tombrockman6225]

love all the new video,s , thank you ... im watching for BFO STABALIZATION MODIFICATION VIDEO for my old receivers NC 183D,,,,, HQ 160,,,,,,,, HQ 100...

[@tennesseered586]

Very informative. I didn't know about M meaning kilo on the old schematics. Thanks for that, Paul!

[@donl1846]

Awesome as always Professor Carlson, thank you for sharing..........

[@MrCarlsonsLab]

My pleasure!

[@billstoner5559]

I’m curious, Paul. You may have answered the question in some earlier video, but… Where did you get your electronic education? Do you now teach at university or tech school? Greatly enjoy you videos. Thanks for sharing your knowledge. 😊

[@ljubomirculibrk4097]

Hello One more quality video, thanks! Cant be a dielectric problem in mica caps, must be a housing degadation-moisture...

[@MrCarlsonsLab]

You're very welcome!

[@dbingamon]

That new lab looks great

[@MrCarlsonsLab]

Thanks Daniel!

[@dffabryr]

A real master !!!

[@Greg-et2dp]

MR CARLSONS LAB YOUR VINTAGE RCA CR-88 SHORTWAVE WITH SSB DESKTOP RECEIVER IS AWESOME I LOVE VINTAGE SHORTWAVE WITH SSB DESKTOP RECEIVER 😊😊😊😊😊😊😊😊

[@KeritechElectronics]

Schematic and unit quirk wise, I've never encountered M for kilo, but I've seen Polish schematics with T for nanofarads (as in Thousands of picofarads), or µµF denoting a picofarad. And like in this schematic, capacitances with no unit specified are in picofarads. Nicely repaired :)

[@domenic5136]

Another great video, I learn alot from them.

[@solarbirdyz]

I don't have a fraction of the experience you do but I can't think of a time I've seen a variable cap shorted like that when there's not also some other clear impact damage. Of course, I've never worked on anything as sturdy as this beast so maybe that's it - whatever happen left no obvious damage here, but would've on a plastic housing, or something like that.

[@UKDrew]

Awesome as Always...Thankyou for another Great Video... Pleasure to watch and Learn

[@drtidrow]

5:40 I've got a Hallicrafters S107 that does something similar - for the BFO input they have a capacitor on the schematic that's marked as a "gimmick", and in the radio itself it's just one turn or so of insulated wire around one of the lugs of a tube socket.

[@HavingFunRepairs]

Really wished I had the knowledge you shared at 3:40 prior to when I started restoring an old Triplett VOM. Learned that lesson the hard way.

[@Steve-GM0HUU]

👍The old convention where 100M indicates 100,000 Ohm I think may stem from Roman numerals where M was a thousand. M for Mille (Latin for thousand). Another very interesting video Mr Carlson and thank you. As well as more top tips and technical information, this prompted some reminiscence of bygone days trying to tune SSB on old BFO comms receivers. It's a little tricky but with a stable VFO and some practice it can be done as demonstrated. Using the RF gain to adjust the SSB level for better product with the BFO is a good trick that some may not be aware of. As you demonstrated it makes a huge difference, especially with stronger SSB signals. That bent plate on the BFO capacitor was odd. Maybe some previous owner was an AM only guy and wanted to make sure the set couldn't receive CW 😂.

[@richardcranium5839]

first time i heard of mica was helping (lol) dad replace the "windows" in our old moore heater. really interesting stuff if you caught the edges of the old ones that had been heated and cooled thousands of times you could flake it off in layers. no so with the new stuff.

[@A.A.ron77]

Well, that was amazing. you found a bent variable cap, and were *actually* able to bend it back easily, and pick up audio!!! wow. I wish anything in my life was that easy. ANYWAY, what antenna is the receiver at that point?

[@MrCarlsonsLab]

You can look up my "369 Antenna."

[@leonardpeters3266]

Such a beautiful receiver. Well worth the effort. It is interesting that most of the glitches seem to have been human induced. That seems to be a theme that runs through allot of my repairs too. I wouldn't say 100%. But I'll bet 40 --- 60.

[@jeffryblackmon4846]

Very good video.

[@mp6814]

Fantastic vid, thanks!

[@MrCarlsonsLab]

My pleasure!

[@tonyking9235]

ME THINKS THAT MICA COULD BE SUSPECT . HO WELL LETS SEE MR CARLSON WILL FIND IT . HE ALWAYS DOES 😊😊😊😊😊

[@Ultra-Violet]

Thankyou Mr Carlson 👍🏻

[@MrCarlsonsLab]

You are very welcome!

[@muddyexport5639]

Thanks!

[@MrCarlsonsLab]

You bet!

[@jrkorman]

@MrCarlsonsLab - Where is that capacitor labeling documented. I've got my old (1951) Allied's Radio Data Handbook and for a 6 dot cap it shows that as the greatest significant digit of the value. Thanks for a great set of troubleshooting videos.

[@MrCarlsonsLab]

There are many on the net, this is correct, (the first blue chart down from the top) www.tpub.com/neets/book2/3g.htm

[@hiscifi2986]

I think one of the main assets of the AR88s was that it had two tracked RF stages before the first mixer. This meant that non wanted signals were over 40 db down on the wanted signal, at the mixer stage. Modern transistorised transceivers have untuned front ends, and just rely upon the first transistors, and mixer, to have good strong signal handling properties.

[@benjaminbrower540]

How many radios have you built? I'm thinking you should build one for KZbin.. Awesome stuff as always Paul.. love the educational leave you bring

[@ClaymateDesigner]

Very interested in your homebrew capacitor leak tester...

[@stephenhemsworth2649]

The AR88D version of this does have some white spot paper/foil capacitors that look like micas in the RF box. They are longer and darker in colour than the actual mica ones, about 15x27mm. A couple of them are really difficult to get at.

[@parlance.electricco]

23:00 that glorious mystical sound first heard and loved during childhood years DXing (people used to think I was a girl until my voice broke and it used to annoy me so much)... imprinted into my neurons...

[@jptucsonaz8503]

Hi Mr. Carlson, Great work as always! 🙂 I did notice @ 20:48 when you moved the camera, the the right side of that BFO variable caps plates still look off-center, especially the upper right one. This could just be the camera placement, but it looks very close to touching as well. Like you said... 2 caps with shorted plates... Wow! How strange. Makes me think the unit was dropped at some point! 🤕 A much closer review of all of the mechanical moving parts seems warranted! Checking for bent shafts, cracked bearings-clips-etc., or loose hardware like grounding straps, or solder joints. Even metal fatigue cracking. Back in the day while in the military, I had an very used piece of aviation electronics that I kept finding odd things like this... Eventually 17 or so major flaws and hours upon hours of inspections and testing and never being able to get it to work within specs, until I hit the one broken part that was irreplaceable and had to scrap it. Further investigation found that the squadron tech had slipped and dropped the unit to the deck in order to catch his balance and not fall off of the back of the plane - in this case, a better choice! Of course, it would have helped knowing that up front! I look forward to the rest of this radios' troubleshooting, and the improvement mods, including the product detector. That should prove interesting. Oh, one last note... Those really old & oddball schematics with the non-standard marking (by today's STDs) ... I take and make a big RED note on copies indicating that fact, then mark in red the "k" in place of the "M" In those locations. Otherwise, you'll confuse yourself and others not in the know, and that disrupts your troubleshooting mindset trying to remember silly little non-conformaties...

[@scotttodd3506]

Great video as usual- have enjoyed all the ones on this radio's restoration, but shouldn't C83 and C84 be referred to as DECOUPLING or BYPASS caps rather than blocking caps? The latter would be used from the plate of one stage to the grid of another to block DC and pass the signal.

[@arsimahmetaj6272]

Excellent work

[@humbuccaneer84]

Lately fascinated by. Neon bulb relaxation oscillators. This is really beyond my bulb... A metal rail. In place of 3in1 caps... keep chassis original and hole free.

[@tomwilliams8675]

I wish I knew more, but very cool.

[@ElieWar]

M is the Roman numeral for 1000

[@tomharris1457]

That was fun! Tnx

[@wansolve289]

Grest video series Paul, thank you for taking the time to put this together. Question; when you replaced those bad Mica capacitors you opted for Poly replacements, what was the deciding factor against using modern Mica caps?

[@MrCarlsonsLab]

You will hear the explanation in the previous video of this series. (one back)

[@utubejeffo]

I dearly love the easy ones. Some fumble-fingered tech goobered the little variable....or somebody tossed something in there, like a manual or a cable. Good job as usual! I still wonder why RCA printed the tubes upside down on the schematic!? Thanks Mr. C.!

[@vincenzofidanza2539]

Hope you show a product detector in circuit made , connected and tested on one of these receivers, thanks.

[@georgek2734]

You Have a little spider running around his web below that vibrable cap between 20:23 and 20:25 😂

[@kenanshobbies9970]

Paul: Great video! And not just this one! All of the videos in this series are great to watch. As a fellow ham radio operator and an at-home radio repair technician (not to mention a Patreon supporter) I find all of these videos, a wonder resource for me as they aptly fill in the gaps of my ever-growing troubleshooting experience. I have a question about your Agilent U1252A DMM. In previous videos, you have used the Agilent/Keysight model U1253B with the OLED display, but I don’t see it here in this video, nor have I seen in the past several videos of yours. I’m curious if you still have and use it, or did you replace it with the U1252A? The reason I’m asking is because I am considering getting rid of my U1253B. I absolutely love the meter, but I cannot stand the battery life on it. It seems as if I’m always charging it, or, if using an alkaline battery, always replacing the battery. I’m considering replacing it with a fluke 87V. What are your thoughts? I don’t know if you like to do product reviews, but it would be great to see a video or two from you describing the test equipment that you like to use and why. Thank you for taking the time to read my lengthy dissertation.

[@itsonlyme9938]

Looking forward on how to reduce the drift on SSB. I am guessing an voltage regulator for the heater on the local oscillator and bfo and my be a zener diode for the 150 v plus rail. I have noticed on my AR88 the VR150 voltage does change by about one volt when the RF gain is reduced.

[@williefleete]

There something enjoyable about adjusting the voice pitch using the BFO

[@Greg-et2dp]

MR CARLSONS LAB I LIKE YOUR UTUBE VIDEOS 😊😊😊🎉🎉❤❤

[@geraldhaggard1018]

I'd been a little confused about the BFO, thanks for the information. Do believe I can trace down A BFO issue in a Hallicrafters receiver I own. Thanks again.

[@MrCarlsonsLab]

Glad to help Gerald!

[@drtidrow]

4:20 Yep, the 'M' is the Roman numeral for 1000.

[@irondogindustriesllc9025]

Do you light your lab/repair area with LED lights? Is there anything special about them? Would you recommend replacing fluorescent bulbs with LED replacement bulbs?

[@bacca71]

Back in the day (50s thru early 60s), "M" was a thousand, "MM" was a million (analogous to 'MEG'). I recall a rather awkward transition period when that changed - really confusing.

[@762Scott]

Kind of like when they went from cycles to Hertz. Not particularly confusing but, yes, awkward. I grew up with kc's and mc's. I like them better, ha.

[@richardcranium5839]

i suspect those micas drew moisture. am surprised the chassis is not rusted.

[@alexkay1874]

12:18 how do these blocking capacitors accomplish what you are describing ? I see they are connected to GRD how is the frequency it is shunting to ground Determined?

[@MrCarlsonsLab]

You can research, "Capacitive Reactance."

[@OldePhart]

I'd love to know what occurs that makes them noisy but I imagine you would need more careful disassembly and a microscope. It just sounded like arcing so would there be visual evidence?