How to quickly fix antique tube AM radio hum advice by D-lab

[@joesheehan5475]

Mr D LAB! I have an old beautiful Firestone from the 1950s and it was humming loudly, I watched this video and replaced the electrolytic capacitor, researched the sizes I needed from a website. I couldnt believe when I powered it up and hear AM! Thank you man. This radio is no longer just a nice decoration. This is the first time I ever attempted a repair, but there’s no one around me that can do this stuff. You guided me thru it, I really appreciate it.

[@cheycasters]

Terry, you just do "it the right way man", Thanks! All the way from NW MONTANA USA!

[@kornami8678]

I like the Northrop Grumman shirt. I worked for them in Rolling Meadows, Illinois, the old Hallicrafters place, for 39 years and then retired.

[@daveogarf]

Yes! Please cover skip, by all means! We in Cheyenne, Wyoming were able to listen to KOMA-AM from Oklahoma City. It was a clear channel station, and most nights came in very strong. They had an informal contest to see how far their signal extended, and got one DX from Clark Air Base in the Philippines! That's a Hell of a journey!

[@ginkumpow3726]

Unbelievable how clean it is inside.

[@derkdiggler4995]

I love that old stuff and the way you keep it simple for us new guys thanks!

[@esdamiani]

Beautiful radio and Mach 5 car! !!

[@jimdawes7261]

That radio is so clean with so much room under the hood, I've noticed that RCA seems to cover parts of the chassis with plates in this case the whole thing. Nice little radio, nice vid.

[@d-labelectronics]

Thank you, it was a fun project

[@nivlac5]

I like this is GREAT way to get more people interested in electronics and ham radio. I really enjoy see people restore old tube radios, Terry you do an awesome job! Your warning about all American 5 radios should be heeded, you don't want to get zapped !

[@bobtpapa]

Great job on this project. I appreciate your getting right to the point and then moving on. No long drawn-out chatter. I am a first-time viewer of yours and I subscribed! Where do you get the caps that you replaced the old ones with? My first business as a kid was getting old TV's that were not working and making them work. My favorite was a Crosley table-top 12" FM/TV (1948 model?) Had a spinning channel selector and covered the FM band including aircraft freq. I listened to the local airport traffic! I was around 10 and it was 1959...

[@RuneTheFirst]

There were a few radios made at that time with bottom covers. Jewel (later made by Trav-ler) clock radios of 1953-5 had elaborate bottom panels. There were also a few Emersons with them. I was told by an old service guy that this was to try to minimize interference from nearby TVs. I don't know about that but it was an obvious expense that the public would not know was even there and died out with the switch to printed circuits.

[@jeffmitchell5847]

Terry's best line......"Clippety Do Dah" when referring to the clip holding the filter capacitor in place. I have heard him use it before. A classic. Honorable mention goes to his referring to the old WAX Caps as "Drippety-Do's" Don't you just love it?

[@moodyga40]

love your approach i do the same thing change them all 50/60 year caps

[@jvin248]

Good to change them. The main issue is curiosity -- which was 'the one' that caused the problem? Put a meter on the pile of removed caps to say "yep, it was this bad one right here!"

[@smstiao-tecnologia]

Nice repair mr. Tery ! This old radio have sound super clean.

[@toddgrimes3710]

Speed Racer...very cool. I have the same car. Where's Racer X? I enjoy your videos. Keep them coming

[@russellhltn1396]

Isn't he riding shotgun?

[@mikesmuseum]

I agree, totally. Why would anyone waste their time checking 60-year-old capacitors?! What the heck for?! That's like testing 60-year-old spark plugs 😂 - what fool does that, lol?! Put new caps in there and be done with it! Great video - Keep up the great work!

[@aftershock2222]

I love watching cap changing videos. Thanks!

[@tomj4506]

Most important thing you said is ONE AT A TIME ! Wish the newbies would listen to that. C U later Tom a.k.a. Zeno LFOD !

[@jvin248]

Speed Racer, I remember when that was on regular television.

[@Blaydrnnnr]

Still amazes me how those tubes hold up so well.

[@f.k.burnham8491]

Good job on that one. I always use a metered isolation transformer and variac combo when testing myself.

[@pedroizaragozablanco5981]

In México I was able to fix my tube radio with your video

[@corproblox3874]

this helps a lot as i just got a Marconi from 1954 with the same issue, thank you

[@danielthomas791]

….WOW!!….when you're good, you're good and you are the best...THANKS!!!....

[@akdenyer]

Hi Terry, When I have done old valve radios I used to always check the anode resistors as they used to go high. I have not seen you check any of these. Do you ever check them? Those capacitors used to be great fun. One radio I did had a solid block of multiple capacitors in it. Luckily I had a diagram so I could reproduce it. Otherwise it was just a pitch block about 5"x 3"x 1.5" with wires coming out. That radio was about 1936 if I recall. Anyway great videos and a very professional approach to repair. Moist impressive. I used to run a small radio repair shop and loved these old radios. But sadly the days of commercial domestic radio repair are largely over.

[@Finom1]

Your amazing, thank you for sharing your wisdom with us!!!

[@clifffiftytwo]

As your title implies, a quick and straightforward approach to fixing hum in a radio. Additional topics in the comments are use of a variac and isolation transformer and replacing the power cord. Not everyone has these items but can still repair a radio with hum using this video. Additional items are covered in your other videos.

[@kazzTrismus]

you should really cover "skip" for the younger generation...they are fascinated by it and most have no knowledge of it at all...its a really amazing topic.. great video thankyou!

[@Blaydrnnnr]

LOL.. I didnt even think of that...I'm old as dirt and it was a common thing. Late at night hearing stations from far away places.. ( relatively speaking..)

[@videolabguy]

Get a transistor pocket radio that works well. Late at night, stand beneath a power line and you can tune in stations from thousands of miles. I presume it is inductive coupling to the long wires above. This should blow a kid's mind! I would listen to horse race scores from Arizona in northern California (Red Bluff) late at night in the summer and marvel at the range I was getting from a mere six transistors! Actually three transistors if you didn't count the audio amp portion.

[@mikec9537]

Another great video Terry. I. was surprised you weren't using an isolation transformer when powering it.

[@LouinVB]

Sometimes it's not so simple. Zenith 7H921. Not only did I replace the filter cap with one custom made by Hayseed but I also recapped the entire chassis. 60 hz hum is still there.

[@knottreel]

Nice fix. If you ever get the chance, I'd love to see a radio alignment.

[@danielthomas3057]

To make it safe you should have replaced the power cord with a polarized cord with molded plug. Then rewire the power switch to the hot side of the set rather than the chassis or cold side in the case of a floating chassis. A fuse in line before the switch would also be a good idea. I do agree with replacing all the capacitors. An IF/RF alignment would have optimized the radio's performance.

[@willrobbinson]

very good clean repair. those wax caps did need to go for reliability

[@caulktel]

Thats a nice AA5 radio, great restore.

[@MichaelLloyd]

One of the first pieces of test equipment that I restored was a cap tester. It works great. I almost never use it. When I do it's just curiosity not necessity.

[@barbmelle3136]

From Leo: People get silly about only replacing a single failed part. I was a bench tech for an Instrument company. We rebuilt controls that had been in the field for years. The main controller chassis had four 741 op amps. I would just snip all 4 of them out and replace them and a couple of electrolytic caps before I ever tested and calibrated the board. I could do this faster than setting them up to test and diagnose. I never got a controller in that did not need at least one. Those 741's in bulk were about 50 cents each, Obviously a tech bench and overheads for a fortune 100 company costs more than that a minute. We got a new foreman, straight out of business school who tried to write me up for wasteful work. I got it reversed as preventative maintenance, and higher quality for the customer.

[@MikeY-hl5pi]

Very informative. Thanks for sharing.

[@rockettcrawford890]

My favorite youtube channel.

[@K7MD]

Good Job. I would replace the bottom and back case screws with nylon ones.

[@daleburrell6273]

...do you think nylon screws would be strong enough?

[@dougmcartin3881]

That is a really nice vintage set. Don’t think it was used much. Getting hard to find them in such good shape.

[@rciancia]

Terry nice, job. Did you add a polarized cord and make sure the HOT side goes thru the switch ?

[@d-labelectronics]

Nope, cord remained stock

[@robozstarrr8930]

nice, for a little more safety, why not recommend using a 1:1 AC isolation Xformer when repairing hot ground chassis equipment?

[@roberthurless4615]

You didn’t have a glass of Robert Mondavi when you finished. Lol

[@robertcalkjr.8325]

Thanks Terry! That's a nice little radio. I wonder how much that it would be worth now?

[@daleburrell6273]

...clippity-doo-dah...clippity-ay(?)

[@Bhamgurl1]

How about an IF alignment? It's had to drift out of alignment over 50+ year's

[@nor4277]

That radio looks.brand new

[@jamesmdeluca]

Greetings: Since the subject of isolation transformers was raised; I agree they should aways be used when working on all hot chassis units while using them wit isolated units is wise as well. i have not seen this option mentioned before, but switchable 110-220 vac transformers can be used as an 120:120 isolation transformer bypassing te switch or jumpers and using one winding for input and the other for output. Yes, only half of the original power rating is available. OTOH: When restoring a unit designed for lower mains voltage than the higher mains voltage encountered today; I would replace the 5V tube full-wave rectifier with a pair of 1N4007 diodes and using the 5vac winding to reduce the input voltage to the input winding by wiring it out of phase with the primary to subtract the AC reaching the input winding. Some people will worry that he diodes being more efficient than the tube will result in higher B+ but I think that is nonsense. Don't forget the 5vac must only be connected to the input side. Hope this helps.

[@evananderson8452]

Great Job. Should an old radio like that have the plug changed to a grounded one?

[@ianbutler1983]

Evan, polarized is the usual answer. That way the grounded (neutral) conductor is always the one connected to the chassis. Otherwise there is a 50/50 chance of the chassis being hot.

[@nor4277]

Just once I would like to find a tube radio that in that one condition,it looks new someone cared for it well.nice repair .I like your idea of replacing all the old caps to start fresh ,that what I do ,so I don't have to do things twice,I might make a exception with a transistor radio ,but a old cap is a old cap ,I just got a G.E. MICKEY MOUSE RADIO THATS solid state I will probably shot gun the caps ,but the radio plays perfect ,I may wait a bit ,but I am going to do the filter cap,or should I shot gun then all? Anyone or Dlab

[@dhpbear2]

6:40 - That twisted-together resistor and mica cap looks a bit 'Howya Doin' :)

[@2right4words]

Terry, you didn't check any of those old antique resistors?

[@kevinwallis2194]

found your youtube channel searching this exact problem. Im working on a 30s-40s coin op radio. I would like to know how to determine what caps and where a person might find replacements.

[@joewood2222]

Hi how to you know what caps you need or what capacitor replacement to use. Gonna try my first ave time repair any help would be great thanks

[@DavidBerlind]

I have two questions Terry. First why no alignment?

[@DavidBerlind]

2nd, what's your rule of thumb for capacitor replacement? For example how many microfarads and volts were supported by the original capacitors and what were the ratings of The replacements? You mentioned the voltage and I know you can go higher on the voltage. But what about the capacitance?

[@jonpardue]

The trusty B&K tube tester!

[@RobertKohut]

Nice!!... One more generation of enjoyment... :-)

[@NebukedNezzer]

nicely done

[@preiter20]

Nice shirt swag Terry! I have a Hallicrafters S-120 that has loads of static noise at 700 k.c. And below. I cleaned the tuning capacitor with Deoxit checked for contact of the fins but can't seem to find the cause of the issue. Unit has been completely recapped and performs great above 700 k.c. Any suggestions?

[@preiter20]

Paul J Pachasa JR thanks Paul. I will take a look!

[@christopherhowey5426]

On the Panasonic 630v replacements were there any other numbers on it that I need to lookup. Im working on my old tube am radio that I bought. Its almost identical to the one u fixed.

[@williamreadon9052]

it would be completely insane not to replace all the original caps they were old tech and never meant to last as long as they did, why not take advantage of modern tech for literally pennies love the vids they remind me of my dad fixing the old tube tv and radios

[@robertcalkjr.8325]

I would have replaced them before I ever plugged the radio to a socket. I just don't understand why someone would take a chance of doing more damage... You're going to change the caps anyway - why not look into the radio and change the caps first before you plug it in??

[@johnmoyer2849]

I check thefilter caps for a/ c .Then replace them and any other caps.

[@kwacz]

what if you replaced all the capacitors and even the resistors and it still hums?

[@dhpbear2]

1:37 - One thing I've NEVER seen re: these types of radios is it running on DC!

[@mikewmount]

These are AC radios and the AC is converted in the powersupply to supply DC voltage to the tubes.

[@kenbarr3486]

I have sane rca 3x 535 with same problem. Where can I get capacitors you used?

[@rubenproost2552]

Am band is virtually empty nowadays where I live. Same with long wave and short wave. Only fm is still crowded, well for another 10 years or so before that disappears. Already disappeared from cable.

[@eugenetheodore2956]

Hello. I recapped a Majestic radio & replaced resistors & 2 bad tubes. When I turn it on all I get is a low volume hum. Going across the dial produces nothing. Do you have any suggestions?

[@johnsimms3957]

About how long will the new caps last?

[@dd313car]

You don't care about the outer foil side of nonpolar caps ? OK, it will work but mostly with more hum. Unfortuneately newer caps have no longer band markings for the outer foil. If build in properly the outer foil works like a shielding and reduce hum and interfearence. But with an oszilloscope you can find out where the outer foil side is. The marked side of a cap should go to ground or the lower potential. On old caps those side is marked with a wide band on the cap .

[@jsaylor1229]

I'd like to know how to convert that to a guitar amp maybe raise the output wattage if possible

[@inerlogic]

I've got a 5 tube GE with all new caps that still hums :/

[@ZnenTitan]

Now the chassis on the radio is just as "hot" as the one on the Mach 5.

[@bingojamas4786]

Hello. I just recapped this exact radio and replaced any out of spec resistors. It played BEAUTIFULLY for a couple of days and then stopped completely! I checked just about everything : different tubes, all coil resistances, component values, the usual. All voltages are spot on except on the AVC line going to the first two grids which is at 5V! I even replaced the couplett. No change. I can hear the tone from a modulated signal when I radiate it into the loop antenna just fine. Otherwise it is silent. Help anyone?

[@tiki_trash]

Did that radio have a differentiated AC plug? (hot and neutral)

[@bobvecchi7981]

That would be a “polarized plug”. Probably not, unless it had been changed at some point. But that wouldn’t guarantee safety. But he should have used an isolation transformer which would have eliminated the shock hazard.

[@mahmoodalam1616]

Very good I am from India

[@allmc2008]

Can a bad 12at6 tube cause a hum sound on a record player

[@richardbrobeck2384]

Nice

[@snoobiedoo6705]

I myself would have went straight to the pens instead of the J hook method would have left a cleaner look other than that I enjoyed your video

[@thegreatfixer]

i am wondering how much power this consumed

[@inerlogic]

They make nice space heaters

[@russellhltn1396]

No tricks? But I liked Trixie!

[@Only1Shadow]

Hey why don't you get a cap checker... Lol. They're all bad or soon will be. Mica and Ceramic will survive, but just about anything else from that time will be dead or dying.

[@michaelalbro6856]

Hoping racer X wasn’t in there.

[@TheTrueVoiceOfReason]

Chim Chim, get your toe out of my eye!!!

[@TheTrueVoiceOfReason]

I was waiting for you to do a Pops impersonation. "I gotta get in shape! One two. One two. One two. Ooohhh my back!"

[@NebukedNezzer]

A "Loop Stick" antenna is wound on a ferrite rod. this is NOT that. its just a "loop" antenna.

[@daleburrell6273]

...the radio HUMS because it doesn't know the WORDS?!

[@rayislooking2]

Go Speed Racer

[@SteveHacker]

Great video as always, but NOT NEARLY AS EDUCATIONAL AS IT COULD BE if you’d actually show the work, rather than just showing it already finished. I’d MUCH RATHER see an entire hour-long video of every bit of the work being done, than a 9 minute video that amounts to little more than glorified “before” and “after” snapshots. The people who need the education need to see how ALL the work is done, and the people who don’t need to see all the work likely already know enough that this video teaches them nothing new. GREAT channel, and GREAT video, but really it’s little more than a “teaser-trailer” for the full-scale instructional video that should follow...

[@isoguy.]

Agree with sentiment, though we should be thankful that he takes his time to show us anything. Ive always said our legacy to the next generation is not the fame or money we collect in our lifetime, its the skills we pass on for which we will be remembered. Its our duty to teach the next generation, not to see how much money we can get out of them for our skills. (Mr Carlsons Lab for example)

[@d-labelectronics]

You rock man

[@SteveHacker]

ISO Guy ... Oh, I totally agree! The world would ABSOLUTELY be a lesser place without Terry’s videos...

[@n8nkqrp595]

Oh oh. Watch out for the Purists! Coulda restuffed those beautiful nasty old wax and paper caps using little multilayer ceramic caps then resaled them using original or recovered bee's wax. I'm outta here. Purists are freaks. PS - thanks for not using junk Chinese bright yellow axial caps from an auction house. They'll fail in a few years I'm sure. 73 OM