Check out Radio Museum: go to schematics tab www.radiomuseum.org/r/general_el_all_transistor_p_807j.html#pic-tabs-1 You can also buy from Sams Publications: This looks like it might be the right one www.samswebsite.com/en/photofact/details/index/id/59580

You're very welcome!

"Gentlemen, we can rebuild him; we have the technology." The speeding up I did in the edit looked like it came from that show. Thanks!

May be able to watch ebay for one if you want originality. Design-wise, the switch design is a little rinky dink imho. However the schematic which is available online shows the probe on the left side for DIY. If you made your own probes you could just have one with, and one without the resistor and not bother with a switch. Thanks for watching.

Yes I agree, these are really nice radios. I think I will get in there and replace those old cracking wires eventually as it is truly a keeper. Thanks

That turned out to be true, but I guess I just wanted to show how it went together and I wanted to thoroughly clean and lube the pivots because it was a bit tight and the way the tuning knob interacted was it was slipping a bit and I wanted to have it moving easily. It really wasn't that big of a problem just took a bit of attention. Thanks for watching my projects unfold.

Thanks. Glad you like the list. Thanks for the comment.

Hi. You are welcome, glad you found it interesting. Thanks for the kind comment.

Thanks for the note. I did need to take deep breaths from time to time.

Thanks for those points. Yes, for those inexperienced, the use of an isolation transformer is one of the most overlooked essentials and is difficult to find correctly set up for a tech bench. Those for medical applications still pass through the ground/neutral and therefore do not do the type of isolation needed without modification by someone who knows what they are doing. In looking at my situation you will see I placed a foam insulating tube over the exposed post in the middle back of the bench. The other metal points higher up I can manage. In addition to everything on GFCI I have lots of current limiting as well for DUT. The bench top does not have metal railing under it so I have not had any coupling issues thus far. When soldering, the soldering pencil stand comes down to the bench top so I do not park it overhead when in use. I am definitely space limited so access behind is not possible for me. Thanks for the comments.

@@PracticallyFixed , I don't work on vintage AC-DC transformerless radios, and I'm retired from Audio repair now, therefore on whatever projects I do on my own, an isolation transformer isn't strictly necessary, but if I was working on such radios or using an oscilloscope a lot then it's really a good idea to have one if for no other reason than to prevent blowing up sensitive equipment (including vintage VTVM's). By the way, I've noticed from watching KZbin videos reviewing modern digital soldering stations that are "clones" of the more expensive pro-grade stuff, some of them leak fairly high voltage at low current onto the tip and could cause all kinds of weird behavior with associated test gear or perhaps damage sensitive IC's and components. One guy opened up a Yihua desoldering station to find that it switched the neutral instead of the hot and had all kinds of other construction and design errors built-in.

Isolation transformer was front of mind as I am about to work on a true hot-chassis set, without even the (now failed) capacitor isolation. Fact is, none of the videos here or elsewhere are instruction of fundamentals, including safety. I don't know where younger or inexperienced folks get the fundamentals these days as I believe classes on this in public schools are long gone. Being raised by an engineer "helping him" with tube gear (including TVs as we all did) as a kid, and then working in the R&D department at TI as a teen I picked up most of my initial training then, which of course continued in my working life (also retired). Newbies need an "Elmer", as in the ham world; I have never seen adequate instruction in fundamentals on any channel here. Just no substitute for an old hand looking over their shoulder and correcting someone as they are making an error. As mentioned, these videos are intended for just entertainment for folks like me who enjoy watching folks puzzle through troubleshooting and how to use logic based upon their understanding. I am trying to give back by videoing my own projects. Interesting point about the irons (I think I saw that video you mentioned a while back). Perhaps I should open mine up and take a look. Have done a lot of work with it and haven't damaged anything yet (have been using this unit for about 15 years), but you got me interested. Saw shango do a review recently of a station which created noticeable RF interference for him; my soldering station does not do that to a noticeable extent, but my relatively new hot air station does. Wonder if FCC relaxed their regulations to facilitate all these lower cost switch mode power supplies that are everywhere now.

@@PracticallyFixed , I don't know if the FCC specifically relaxed regulations on RF emissions or if UL safety codes have been watered-down ----- but with so many people buying "cloned" or counterfeit equipment directly from Asia, basically they get what they get because there is little to no regulatory oversight of such equipment. If you watch Big Clive's channel, he frequently does teardowns and reviews of equipment that turns out to be highly dangerous. But anyway, younger generations typically don't have the chance to learn electrical and electronic safety until they make a major mistake which they might not recover from. Learning to use power tools as a kid in the late 60s, I discovered what could happen if you were using a metal cased, ungrounded power drill while standing barefoot or in damp moccasins on a concrete slab floor in the basement or garage. Our schools had wood and metal shops,, auto mechanics for the gearhead types (wasn't my thing), and an electronics shop.. We subscribed to Popular Mechanics, Popular Electronics and other similar magazines as kids, so we were always reading about electrical and electronics projects that you could do yourself. In 1970 or 71 my dad, my younger brother and I partially gutted our cottage at the beach, rewired the electrical, improved the plumbing, and changed out all the windows and put up new paneling. I got zapped a few times by the power tools and I was much happier in the late 70s and 80s when double-insulated Bosch and Makita tools came out that didn't need grounding and wouldn't shock you through the plastic casings. Nowadays, of course, the prevalence of cordless tools makes both pros and DIY-ers even safer. Also, as an amateur guitar player, and still amateur all these years later, we all found out the hard way that playing guitar while standing on a concrete slab could zap you because the strings were connected to the chassis of the amp. If you want to see videos on KZbin where the techs are very careful to remind people that amplifiers should always have a 3 wire earth-grounded power cord, watch guitar amp repairs. The good techs are all very careful to reiterate this fact over and over, and to point out when the switch or fuse are placed in the neutral line instead of the hot line, or if the chassis grounding is done in a way that's unreliable. By the way, I posted some soldering related videos on my channel recently including a review and tear down of a $45 Harbor Freight Schneider soldering station that isn't half bad for the money (certainly much better than what I had to work with as a kid in the 60s), as well as an investigation into the crappy direct-from-China soldering iron tips that are so prevalent on the internet nowadays. It's one thing to buy a cloned soldering station direct from China, but people, especially newbies to soldering, are really better off buying name brand tips, solder, flux and other accessories from authorized distributors in the US instead of buying from faceless Asian sellers. If you skim through the comments of any soldering-related video on KZbin, you will find dozens of people complaining that the solder "won't stick to the tip" or "falls off the tip", or "it won't melt, it won't flow"...... and of course,"what am I doing wrong?"

Hi. I cannot say. When doing some research on this unit, I did see it "somewhere" that it was important that these audio output OP Amps not be run unloaded or they could fail, and since these ICs are extremely hard to find, and the unit did not belong to me, I thought it would be irresponsible of me to not take that precaution. I do know that in general, it is something I have heard about for decades regarding amps, and the Sony R2R, with vacuum tube output amps, that I just had on my channel had an internal 8 ohm load on each speaker connection unless the speaker was plugged in. Likely the answer in general is, it depends - for this unit, I played it safe.

Thank you. ​@@PracticallyFixed

Where did you get the schematic, and do you know if the 8 track portion had a gain level adjust for tape playback. I have this exact radio, and it plays quad tapes great, but regular 8 tracks are quiet. ​@PracticallyFixed

The schematic I used was sent to me by the radio's owner but it was from Sams Publishing. Search samswebsite. It was from Ford 5FD4804 which it says includes D8AF-19A188-AA. $22. There were some differences between that and one of the circuit boards inside, which does happen sometimes, but it worked for my purposes. If you have a different part number you may want to see if that shows up at Sams. I do not know of a gain adjustment like you mention. There is a troubleshooting table in the Sams info with a number of components (ICs, diodes, transistors and switches) you can check. There are some differences in those components to check in stereo and quad mode so those unique to stereo mode may be involved. Replacement for some of those may not be available and it is not easy to work on. That would mean checking for continuity and voltages as shown on the schematic and hopefully just some switches and diodes, rather than ICs. Before getting deep into all that you may want to try different stereo tapes to be sure, or maybe take a known working quad tape and tape off the slot so that it "fools" the player's switch into thinking it is a stereo tape as a test. It may be "just" that switch that is operated by that "finger" I mention which feels for the type of tape, or the leads going to it. When a stereo tape goes in, it switches its common from the quad circuit (normal position) to the stereo circuit. If the stereo side of switch is oxidized, (which seems likely due to it not being contacted for decades) you may get the failure you mention. If I were working on it, I would probably snoop around there first checking that switch for continuity and function. You may want to try just operating it a lot to see if it will wake up. If I recall correctly, I think it is a microswitch and you may be able to take it apart (don't lose the spring!) and see if you can clean the contacts. If you get it figured out, please post back here what you found to help others with this unit. Sorry for the long answer. Good luck.

@@PracticallyFixed Thanks for the reply. If I figure it out, I will post.

Thanks for watching. I can barely see these wires. Here is another silver mica surgery video I did for a slightly different design in a GE radio. There are other variations. Getting the right replacement caps can be difficult and if the slugs get moved around too much is can be hard to get them back. In some cases I have had to use a sweep generator to help. kzbin.info/www/bejne/aX-Xe4Ocmt-Hi6s Check out its playlist for the whole project, I think there were 5 videos covering that radio. I ended up using an expensive bit of test equipment to help me get the slugs set right. Not a simple fix. Some of the older IF cans use variable capacitors instead of variable inductors (slugs). Those do not have this problem. That is one of the reasons some folk prefer to not mess with these "newer" radios, as in late 40s/early 50s onward. Glad you enjoyed it. [edit number of parts to the GE 875 playlist]

@@PracticallyFixed Thanks for your comprehensive reply.

Shango066 has shown using the variable capacitor for finding the replacement caps when doing SMD surgery. It is probably the best way to do it. I didn't have the right parts handy.

Thanks. My first exposure to Hallicrafters was my Dad had a S-38B he took onboard ship with him during Korea. I restored it many years ago and if I recall right, it also had a gimmick to do with the BFO circuit. The Astros have been plagued this year with injuries especially with starting pitching. The team had to release a couple of really big dollar contracts that were not producing as well. Been an up and down year.

Right you are. The external wire helped a lot but the missing IF amp really makes a difference. Thanks for watching and the comment.

Hi. Yes I have done this too. I mentioned near the end that I attempted this but the variables I had did not go to low enough capacitance ranges. (guess I need to go shopping, oh no) As shown, [ 1:34:00 and 1:41:20 ] I toyed with adding capacitance in series to lower the range of the variable capacitor, but since I would be choosing between discreet options, 82pF, 100, 110pF etc., I just used the 82 and it tuned in. Thanks for the note. [edit, added time stamps where it was discussed]

Hello Steve. That is a very interesting find. The K-412 circuit (in Sams) looks very similar to the Run 1&2 version of the Atom due to the couplate (this one is a Run 3 without, but still almost the same). Looked in my RCA tube manual at the licensed RCA circuits but this 4-tube version wasn't shown. The case mold looks the same with some minor changes. What led you to finding that connection? Thanks

Hi ya Doug. Thanks. I enjoying trying to diagnose these things and finding out if I got it right. Good luck on that GE, looks like fun. Thanks for watching and the kind comment.

No, I couldn't find it either; not even one advertisement. Appreciate that you watched and the nice comment. Thank you.

@@PracticallyFixed Hey man, been pretty quiet lately. Hope you're still at it and doing ok.

@@knifeswitch5973 Howdy! Been really busy with my son's wedding and chasing bee and wasp issues. Going to a bee cutout this morning and gotta go. Trying to get the next radio done soon - down to the alignment. Thanks!

@@PracticallyFixed well congrats to the newlyweds and I already learned something this morning 🐝. Good luck on your cutout.

Thanks. That's true about the pads. Don't have any replacements on hand. The ones I have are for cassettes and for 8tracks, neither of which are appropriate. Will keep an eye out for them. Thanks for the comment.

They are heavy aren't they? Thanks for the note.

Haha! Thanks. Yeah we had some issues to deal with but all better now. Thanks again.

Thanks very much for the comment! And also for letting us know about those sponges, good info to know.

Thanks! The O-ring substitution was ingenious. Thanks for the comment and glad you enjoyed the video.

Thanks for the note. Good luck. Do keep in touch. I may be able to give you a few tips that aren't all in the video. One of the biggest tips is the location of the motor oiler tubes which I show near the end. The oiling of the capstan bushing has more to it than I showed. Thanks again for the comment and a thumbs up. :)

Thanks. Not bad for 60 years old.

Thanks Doug! Been having a lot going on here but trying to get caught up. Had considered wood but just decided in my case it would delay getting the job done. More project vids on the way. Very much appreciate the note. Very best.

Hi Jim, thanks for the note. More to come soon.

Thanks! Glad you enjoyed it. It was a fun project.

Good meeting you too. Hope you enjoy!

Yes, it is too bad about the music, really missing in my area. Glad you enjoyed it!

Thank you for contributing that! You saw that much of the actual gear in situ still remaining when you got into the industry, and I can imagine some of the "old timers" told you all about how it was to work. They would have known when it was installed, who provided it, training and whether it was to be under wraps or not. I think the concept was inspired and the design, ingenious. Thanks again.

Thanks for the suggestion - I went back to the video to take a look. If you mean the new black power cord, it is located far from the rectifier socket. The lead from the switch that now goes to the rectifier is blue and is a solid wire and is bent away from the socket but all that is hard to see on the video due to 2D perspective - things may look closer than they are. Then I reopened the back to check that the speaker wires were not near any of the tubes and they are all clear. I am pretty sure I check those things, but a degree of complacency does cause mistakes. Thanks again for the comment for me to check it.

Thanks for watching and hope you found that detail interesting. Some things in plain sight that we see all the time and take for granted sometimes have some interesting backstories - such as town names on water towers.

Ok, ok Gord. Come take a look at what your comment and others like it caused! 😊👍 See, I read this, but it took some time. Thanks for the encouragement.

Howdy! That's some good DX'n there. KTRH used to be a 50kW channel but not anymore, so that is a great pick! In HOU we like to point out to visitors that ELP is almost exactly halfway to L.A. "The sun has ris', an' tha sun has set, and here we is, in Texas yet"

Thanks for stopping in. Cheers