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 Post subject: UPDATE: RC-30 Manual Homemade television
PostPosted: Mar Sun 22, 2020 7:49 am 
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Has anyone attempted to create some of the circuits in the RC-30 book? I just wanted to see if anyone has tried them. I am attempting at the Black and White television (Without the IF and tuner of course.) These circuits seem to have a deal of flexibility. Thank you!

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Last edited by Mr. Highlander on Jul Thu 02, 2020 6:34 am, edited 1 time in total.

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 Post subject: Re: Diagrams in the RCA RC-30 book
PostPosted: Mar Sun 22, 2020 4:28 pm 
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I think that most of the RCA tube manual circuits can work. There may be some typos that you would need to find. Many were based on one or another production RCA set or instrument.

The problem for construction with these example circuits, is that they require specialized coils and transformers that were usually not full specified, and now are no longer made anyway.

For something like a TV, you would need to source these components, then deal with chassis layout, lead dress, and adjustment. Might best be viewed as an educational project.

Ted


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 Post subject: Re: Diagrams in the RCA RC-30 book
PostPosted: Mar Sun 22, 2020 7:29 pm 
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Those are the problems I had. I found that Talon Electronics had many of the original parts (Flyback, Vert. Out Transformer, Horiz. Stability coil, Thermistor). You can use the Sams to cross-reference the parts to other manufactures. That's what I did for the yoke. There also were the typos too. In the manual, it listed the video peaking coil as 18uh. However, further research in Beitmans and Sams found that it was 180uh. Otherwise, that was the only typo I found (besides a few spelling errors). They also left out the picture tube circuitry. That meant a picture tube substitution was possible. The manual called for a 16BGP4/16AYP4. I wanted a slightly larger picture tube with mounting rims, so I chose the 19EKP4 tube. The only change would be different voltages for G2 and G4 voltages. Lack of mounting specifications meant other tube subs that were cheaper. The Novar tubes were never popular, only used mostly by RCA. So, while the tubes are plentiful, the sockets are not. Compactron sockets are much more common, so I cross referenced the Novar tubes to Compactrons. Also, since I cut out the tuner and IF sections, the series string filament voltage would be short of the line voltage. So using higher filament voltage Compactrons would help that. Here is the substitutes:
22JU6--17JM6
17BS3A--34CE3/34CD3
15KY8--21LU8
8FQ7--8B10 (Substituted because 8B10 has phase detector diodes and triode sections are similar)
11LQ8 & 1/2 6GH8A--15BD11
6HZ6 & 12FX5--13J10/13Z10 (Used because of higher audio power wattage versus 17BF11 etc.)
1B3/1G3 -- No Substitution.

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Last edited by Mr. Highlander on Jul Wed 01, 2020 9:21 am, edited 2 times in total.

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 Post subject: Re: Diagrams in the RCA RC-30 book
PostPosted: Mar Wed 25, 2020 2:07 am 
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Really a very ambitious project ! I guess it can be done but the real challenge would be collecting all the necessary original RCA special parts... 47 years later ! Also, these were basic illustrative purpose circuits without any construction details, circuit layouts, alignment instructions, etc... a very good experience in building RF/IF circuits from scratch would be needed but I expect any good experienced old HAM will be able to successfully complete such a project. I allways wondered if anyone then ever attempted to actually build the most complex circuits which can be found at the back of these RCA tube databooks. In the RC-28 there's is a schematic for a complete color TV using no less than 30 tubes ! But there's also the following warning note:

"Circuits xxx through yyy are included in this manual primarily to illustrate applications of RCA electron tubes. Because of the exceptionally high voltages (up to 21,500 volts), high frequencies and large bandwidths that are required and of the many special components that are used, home construction of these circuits is not recommended."

Anyway, please keep us posted about your progress. This is quite an interesting and unusual project.


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 Post subject: Re: Diagrams in the RCA RC-30 book
PostPosted: Mar Thu 26, 2020 8:43 am 
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If I could, I would. However, the unobtanium is much greater in a color set rather than a black and white. RCA also advised against it for home construction, as much alignment equipment that I do not have is needed for the coils. I am sure a color TV servicemen with a large selection of TV parts and testing equipment would be able to pull it off.

All right, enough speculation from me. Will keep posting updates on the Homemade B/W set

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 Post subject: Re: Diagrams in the RCA RC-30 book
PostPosted: Apr Fri 03, 2020 12:40 pm 
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Tubologic wrote:
Really a very ambitious project ! I guess it can be done but the real challenge would be collecting all the necessary original RCA special parts... 47 years later !


I was standard practice at one point at least for RCA to provide entire RF coil kits for TV's , I have one sitting in front of me on my desk. I took a couple of items out of the boxes for the photo. These have everything required by the home constructor except the Yoke, Lopt and frame output transformer and the two typical blocking osc transformers.

RCA were very good with documentation and sharing their research information too. I have all of RCA's wartime research papers that led to the development of deflection scanning systems & FM sound etc. In their deflection department, Otto Schade was their chief investigator and produced very impressive theoretical & practical work.

Speaking of something being on my desk, it reminds me of a story that might cheer a few people up in these darker times, but the mods might delete it, if its not funny enough:

A pathologist was being questioned on the stand in a courtroom. The lawyer said to him; now you certified that Mr. Brown was deceased, but what steps did you take to ensure that was the case, did you check his pulse ? No, replied the Pathologist. Lawyer; did you check if Mr. Brown was breathing ? No, replied the Pathologist. Then the Lawyer said; well if you did not check Mr. Brown's vital signs, then how could you be sure that he was in fact deceased ? The Pathologist replied; Because his brain was in a jar on my desk.
The Lawyer became exasperated and replied; Notwithstanding the fact that some, or all, of Mr Brown's brain was in a jar on your desk, is there any possibility that Mr. Brown could still have been alive ? The Pathologist replied, Yes, he could be alive and well and practising Law.


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 Post subject: Re: UPDATE: RC-30 Manual Homemade television
PostPosted: Jul Thu 02, 2020 6:45 am 
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It took 9 months of waiting for parts in the mail, and an estimated 9 days (Right now it 6 days) of completing television. Here are some photos of the television so far. I have to wire up the control boards (The white thing with knobs), yoke, and the picture tube. The octal sockets are for each of them.


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 Post subject: Re: UPDATE: RC-30 Manual Homemade television
PostPosted: Jul Thu 02, 2020 1:10 pm 
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Wow, this is ambitious. RCA made a TV trainer, I guess in the 1940's, where the whole set (a 630) was laid out on a giant vertical board and wide open. I can't find a picture of it now, but I always thought it would be really cool to reproduce one of them.


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 Post subject: Re: UPDATE: RC-30 Manual Homemade television
PostPosted: Jul Thu 02, 2020 5:18 pm 
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Are you going to make the full TV or leave the RF and IF and AF off and just make it a video monitor?


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 Post subject: Re: UPDATE: RC-30 Manual Homemade television
PostPosted: Jul Thu 02, 2020 5:54 pm 
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Scott wrote:
Wow, this is ambitious. RCA made a TV trainer, I guess in the 1940's, where the whole set (a 630) was laid out on a giant vertical board and wide open. I can't find a picture of it now, but I always thought it would be really cool to reproduce one of them.


We had one of those when I was in college, in the TV lab in the electronics department. Still worked perfectly in the late 60's. You could pull the curtains to hide the works, and watch the thing on the 12" CRT mounted at the top. It worked very well, as you would expect from a 630 chassis.

This is the only photo I could easily find:

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Yes, it might be fun to try to duplicate that today, one could get all the parts from a junker 630 chassis. But it's huge, you can see in the photo how it compares in size to the instructor using it for demonstration. Most of us wouldn't have the space to devote to it. I could have had the one from our college lab for the asking, as my TV class was the last one they taught on tube TV, the instructor retired and it was never used again after that. No idea what fate it met.

Now back to the original discussion, I like what I see so far and expect it will work nicely as a video monitor.

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 Post subject: Re: UPDATE: RC-30 Manual Homemade television
PostPosted: Jul Thu 02, 2020 6:02 pm 
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To Tube Radio:
I am going to put a DTV converter inside, and modify it. So a relay (Circled in Blue), serves as filter choke, and to turn on the DTV converter. When the set is first turned on, the relay does not close, as there is no current being drawn, as the tubes are not warmed up yet. But as the tubes start to warm up and start to conduct, the relay closes. Now, the turn on switch on the converter is a push-to-turn on, and a push-to turn-off. That switch is hard-wired to the normally closed contacts of the relay. So when set is first turned on, the converter is turned on, and then, to allow tuning controls, the relay disconnects when the tubes warm up. The tuning buttons are on the front of the panel too (Circled in Red and Green).
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The Tuner:
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To Dennis:

Yes it is very interesting! It seems like many people learned off of the robust 630.

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 Post subject: Re: UPDATE: RC-30 Manual Homemade television
PostPosted: Jul Thu 09, 2020 7:29 pm 
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Alright, so I have turned it on, and the Horizontal Oscillator was running at a very high frequency (50Khz). I noticed that the area circled in red was negative instead of a positive 3.2V. So that meant the phase detectors of the NOS tube were bad, OR that the area circled in blue was not grounded. I first looked at it and saw that it looked grounded. But a quick measurement showed it wasn't even soldered to the tube socket! So I soldered it and it the frequency now ran at 25KHz. An improvement, but not close enough. So I put a 200pf and 470pf capacitors across the 390pf (C22) capacitor, and adjusted the coil on the plate of the Horizontal oscillator. I then got it down to 15.7Khz. But there was one problem-- The High Voltage wasn't developing! I hear the high pitch, but see nothing. I had to disconnect the plate of the vertical output tube, as it was red plating, because the vertical oscillator triode wasn't getting the Boost, and oscillating. I thought it may have been the Horizontal oscillator again wasn't producing a good signal, but a quick input of a 15.7Khz signal from another tube television showed that was not the case. What am I going wrong here? The Fly back and Yoke are all new, so they can't be the problem.


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HO.PNG
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 Post subject: Re: UPDATE: RC-30 Manual Homemade television
PostPosted: Jul Fri 10, 2020 12:26 am 
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So I found out the problem. It was that the damper was bridged by insulation on a wire that melted during soldering. I got a horizontal line on the CRT, but it is dim, so I have to figure out that. The no vertical deflection is on purpose, as I cut the wire from plate to the transformer..

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 Post subject: Re: UPDATE: RC-30 Manual Homemade television
PostPosted: Jul Sun 12, 2020 5:42 pm 
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A few days ago, I got the brightness up. A capacitor (Circled in blue) was getting hot and melty. When I clipped it out, the brightness greatly increased. The width shrank though, however I fixed that. But I still haven't got the Vertical Sweep circuits to start oscillation. Whenever I connect the plate of the Vertical Output tube, it red plates. There is no negative voltage/frequency at the grid, which causes that. I found that the Integrator was put in the reverse, and I doubted fixing it would fix anything, which was correct. So there must be something wrong in the feed back, as there is plate voltage on the vertical oscillator triode because the Horizontal section is operating. I am about to substitute part values. Any help is welcomed.


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 Post subject: Re: UPDATE: RC-30 Manual Homemade television
PostPosted: Jul Mon 20, 2020 8:14 pm 
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Alright, I got it to work now. So what I did was a major tube substitution. I wanted to see if there was an error in my tube substitution, which would cause the no vertical deflection. So I went and bought the correct tube, and socket, and installed them. Sure enough, the vertical comes right up. Here are some photos. I need to swap the vertical yoke terminals so that the picture is not mirrored. Also, the the height needs to be adjusted, and so does the width. Brightness and contrast also need to be debugged.


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 Post subject: Re: UPDATE: RC-30 Manual Homemade television
PostPosted: Jul Mon 20, 2020 8:26 pm 
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Wonderful to see a 2020 person bread boarding a CRT TV..... I hope you have the opportunity to spread your story on other forums...

Robert


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 Post subject: Re: UPDATE: RC-30 Manual Homemade television
PostPosted: Jul Mon 20, 2020 8:36 pm 
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WOW, keep posting pictures and details as you go.

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 Post subject: Re: UPDATE: RC-30 Manual Homemade television
PostPosted: Jul Tue 21, 2020 7:11 am 
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Certainly will!

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 Post subject: Re: UPDATE: RC-30 Manual Homemade television
PostPosted: Jul Tue 21, 2020 2:15 pm 
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Robert Lozier wrote:
Wonderful to see a 2020 person bread boarding a CRT TV..... I hope you have the opportunity to spread your story on other forums...

Not only wonderful, but truly remarkable. The OP recently posted this bit of information in a reply to a question someone had posted in our TV forum:
Mr. Highlander wrote:
...I am a newbie (Sort of). I am 17 right now, but have been working with vintage electronics for the past eight years...


Dave


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 Post subject: Re: UPDATE: RC-30 Manual Homemade television
PostPosted: Jul Sat 25, 2020 1:20 am 
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Another youngster in the hobby! I was learning color TV by the time that I was that age, having already resurrected several B&W sets. The knowledge that you are learning is priceless. Nice work on the TV!

There were some nice projects in the back of the RCA tube manuals. I built a high fidelity amplifier from one out of the mid 1950s, and had it going by the time that I turned 15. I still have it.

My youthful tinkering led to a lifetime career in electronics. Although I now work with SMT chips and components on the job, I still enjoy the tube stuff. Do you have plans for an engineering degree?

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