1940 Zenith "Long Distance" Portable Diagnostics & Electrical - Vacuum Tube Radio 6D510 Part 1 [4K]

Portable Zenith from 1940. Let's go through it and see if we can get it to play and sound good again.
See the checklist which appears, when status changes, for tracking what is discovered that needs addressing in Red, followed by Green when resolved.
ERRATA:
The San Antonio AM1200 Station is WOAI, not WAOI.
NOTE: This is not instruction, it is for entertainment for people like me who enjoy watching projects and the experiences gained. If you attempt to do any of the things in this video you are at your own risk. I am using special tech-bench safety equipment not detailed here so don't take for granted you can just plug these old items in safely without them being checked and repaired correctly. Check out the link below to Mr Carlson's Lab video below.
ACKNOWLEDGEMENTS AND REFERENCES:
[note: am in no way representing how these folks have shown doing these things - I don't even think they would approve.]
Awesome discussion of bench safety including variacs and isolation transformers by ‪@MrCarlsonsLab‬ Mr Carlson's Lab (highly recommended):
• Tech Tips Tuesday, Iso...
Thanks to shango066 for championing the approach of "fix it first", before mass re-capping. See shango066 for many examples of that approach.
‪@shango066‬
Modification method for a commercial Tripp Lite isolation transformer for tech-bench use by Todd Harrison, his channel is called ‪@ToddFun‬
• ToddFun.com: Isolation...
Schematic: Nostalgia Air
Camera: Canon G7X Mark III
Mic: Rode Micro
Video Editing Software: Power Director
People interested in the following topics may be interested in this subject matter: 1940s radios tube radio repair, tube radio restoration, vacuum tube radio recapping, Zenith Radio, Zenith tube radio

[@zorka4098]

Still catching up to your channel. I have restored several of this model radio, one includes the ingraham cabinet. I have been most impressed by these small table models and their ability to pick up long distance stations with that simple wave antenna and the upfront rf amp. Really enjoy this model and it is how I listen to distant ball games in the summer.

[@knifeswitch5973]

Stubborn knobs, sometimes a bit of heat will do the trick. Sometimes…. Nice job! Zenith dialfaces are dreamy 😊

[@jimnewman5596]

Having the RF section makes a big difference in the radio sensitivity, the zeniths that I have worked on seem to sound a little better than the other brands. You did a great job by using the sticky glue to restore the speaker cone.

[@PracticallyFixed]

Hi Jim. Thanks, the speaker dressed up pretty well. Nice sensitivity as you say. I like it. Thanks again.

[@terryblackman6217]

That's one extremely sensitive radio. I very much enjoy the way you present your videos and am learning a great deal from them. Any chance in the future you could show how you align a radio. Many thanks. Terry

[@PracticallyFixed]

Hi Terry, sure. In the next part I show doing the alignment. I may not be explaining in great detail every step (I have already videoed it), but once you look at it you can just ask any questions you have. Am still doing the editing, correcting my misspeaks, etc. Glad you are enjoying the videos. Thanks

[@DERB_Seymour_Indiana]

Hey PF. Looks to be a good one. Some of the Zenith's with the wave magnet were pretty sensitive for sure. I think we all do things a bit differently, but certainly not wrong. My thought is these old radios I repair will not be used very much at all by me or anyone else for that matter. As long as they play as they should and are fairly safe, I think that is plenty. Good job on this one. :)

[@PracticallyFixed]

Hi Doug. It is hard to know what the future holds for the interest in this technology. I am interested in it for the technology, the diagnostic challenge and nostalgic reasons. I think there will always be people who are fascinated by the stages in development of any technology. Thanks

[@DERB_Seymour_Indiana]

@@PracticallyFixed I suppose, but I think the number of those interested has been steadily declining. I think the ones like you and I from our generation had an interest from the beginning as the technology was advancing so fast. Now a days kids just tend to think this stuff has always been around. LOL

[@PracticallyFixed]

True. Here is a story. I was talking to my son who is in his mid 20s now who really likes vinyl records. I asked him why he was so interested in it, thinking of clicks, pops, skips, warping etc. He said it was because it was something he could actually hold in his hand, and if he had a simple player, he could listen to the music as much as he wanted for as many years as he wanted. I said yeah...so? He said everything else is something you cannot see or hold, if you don't have a subscription, cell/internet payment, etc., you don't have it. You have to pay monthly to have it, you never really Own it. Interesting observation since I always saw things like spotify, apple music etc as something new but that may be most of what they know. Even our ability to watch YT is rented. For the tech-minded, to try to understand processors, power and digital semi-conductors and diodes is to understand the vacuum tube. Otherwise the little black chip is just a black box full of black magic no matter how many n-p junction diagrams you look at. The elements of the vacuum tube you can actually see, and a CRT? Amazing. I remember building one of those foxhole radios, you know the ones with the detector made from a pencil point and the flat of a blued razor blade? Just looking at that arrangement, trying to get the semi-conduction just right, I realized I was actually looking AT the symbol for a diode. So that and the galena whisker set up was where they got the symbol. Wow.

[@DERB_Seymour_Indiana]

@@PracticallyFixed That is interesting for sure. Always just took for granted that things would always be there and not go away. Of course that has proven to be untrue. There are lots of things that are simply not around anymore. Smart kid. :)

[@garyk.8674]

I'm between Waco and Temple and i'v picked up that Shrevport station, only at night though, with some of my repaired radios with a long wire antenna. Go Astros

[@PracticallyFixed]

Go Astros is right. They need to get busy, getting swept by Seattle today was bad news. Rangers have been hard to catch.
Considering the reception in my garage/shop that I was surprised at getting that Shreveport station. Not bad without the external antenna. Part 2 will be out soon, and it gets aligned. Thanks for watching and the comment.

[@garyk.8674]

On the stuck knob, i wonder if a little heat, maybe from a hairdryer would work.@@PracticallyFixed

[@hestheMaster]

You never mentioned the safety caps capacitance . Since the spec in the circuit was 0.05uF for both C9's do you put in
the next lowest modern value say 0.033uF? I always thought 0.05uF was way too high but lowering the value too much
may cause line voltage interference in reception. Like your thoughtful repair progress. Very step by step. Steve

[@PracticallyFixed]

Hi Steve. Taking them in the order of appearance: In the case of this chassis, for the "Across the Line" cap, [Line (Hot) to Neutral], I used a X2 safety cap (the yellow one you see) at 0.047uF. I position the X2 behind the power switch so it is not continuously energized when the radio is plugged in. I also like using a fuse (in this case, 0.375 A) so if anything shorts I don't rely on a 15A house breaker to save the day.
For the "Floating Ground (neutral) to Chassis" cap, I used a Y2 safety cap (the blue one you see) at 0.01uF.
Thanks for the comment; I endeavor to use a logical progression and try to identify a serious issue early (e.g. visual damage, prior repairs, blown power or output transformer, or field coil etc) and get it otherwise working with a new output tube grid coupling cap, before changing all the other caps, other work etc. Then I frequently check the working radio after doing one or a few cap replacements to be sure a mistake hasn't just been made or I have introduced a wire dress problem. I use the list so viewers can track what I am doing. I may need to check tubes are correct and in the correct sockets earlier than I do... Following prior repairs is the spice of life. Thanks again.

[@joatmonuk]

Nice little compact unit, can you tell me the name of the glue you use to repair the speaker, thanks.

[@PracticallyFixed]

There is a text note that it is a 50-50 mix of water and Aleene's Original Tacky Glue. I had seen Don @RestoreOldRadios use it a while back as he said it dries flexible, and have had good success with it. I recently noticed Don had switched to a different glue which was acid-free. Turns out Aleene's also sells an Acid-Free product, but I have not tried it yet. You can obtain both in the USA via Amazon or perhaps in hobby stores. Is the cone so brittle because it is made with paper which is not acid-free in the first place? Thanks for watching and the comment.

[@OLDtuberadioguy]

Do you concern yourself with “foil end” testing on your yellow jacket caps? If so, what method do you use for identifying the foil end?

[@PracticallyFixed]

Hi. Since it easy for me to do, yes, but usually I cannot see much, if any, difference. I use an oscilloscope just above my desktop, I hold on to the body of the cap while testing which lead picks up the most hum. Then I mark that lead as the outside wrap with a small back dot next to the lead. I can see how this would be more noticeable for old paper/foil caps, but for these, as mentioned, I usually don't see any real difference, but I check them anyway. Thanks

[@OLDtuberadioguy]

Thanks.
That is what I do also, sometimes hard to even see a difference on the scope. Thanks again.

[@toddcummings7843]

Do you sell these?

[@PracticallyFixed]

Perhaps someday, but not anytime soon. Thanks