#76
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Quote:
Pete |
#77
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FYI, RCA 78891=Meissner 17-6015. I did notice, while checking some Photofacts, that the 19CK1 uses the same part, and I suspect others do as well.
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Bryan |
#78
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L42 was changed sometime in the previous owners' restoration(s).
L43 mesiner 17-6015 (thanks Bgadow for the cross-reference!) turns out to also be used in the Dumont monitor carcass I got at the ETF...Can't say I feel good about taking parts off of it, but others have done that enough in it's history that I'll need a parts chassis to get it working anyway...In picture form I pulled this coil from this chassis to fix the CT-100. Color synch held for 30 min and only wavered on a VERY saturated scene.
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#79
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So as an aside, what is your picture source? As digital, then ATSC came onto the scene, the definition (or common practice) of 'legal' colors and black levels has changed a bit. And if you're converting from HDMI, HDR will really tax things. If you're using 'old' recordings (VHS/Beta) or a proc amp in conjunction with your modulator, or if it has one incorporated within, it may not be an issue.
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#80
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I haf many sigi-nal sauces.
That is the main rack in my room. Bottom-up there is U-matic, LaserDisc, HDDVD, Bluray, DVD-recorder/VHS, DVR/DVD-recorder, 2 S-VHS-ET decks, CED/selectavision video disc player, SuperBetaHiFi, AV switchers, PC with S-video out, ATSC box, Blonder Tounge agile modulators configured to transmit, and hidden to the side a pair of mini cable boxes and a Roku. Before the ETF I tore apart and rebuilt/reconfigured all but the agile modulators on top to fix the flying spaghetti monster that it had devolved into through 3-5 years of not really properly reconfiguring it when needed but instead hacking on to the front accommodations for the switch to digital cable, the addition of HDMI for my HD-CRT Sony, and a bunch of other stuff. Basement rack is a Blonder Tongue, VHS, Beta, CED, Cable box and a fairly literal bunch of video game consoles (also have LD and other crap waiting to be added to it when I get around to rearranging that cluster)... Colorbar path consists of upstairs DVD transmitted, then tuned in by the VCR in the downstairs rack and retransmitted (the upstairs rack is hard to tune in the basement so this is the easiest workaround), then tuned in again by the VCR that feeds this video injection box https://antiqueradio.org/VideoAdapte...Television.htm The TV program path was much simpler cable RF out from cable box (it only has RF for analog output) to the tuner on basement rack and onwards like the other path. The CT-100 shall live in the basement close to my workbench until I am satisfied enough with its performance to make it a spot in one of my upstairs display rooms.
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
Audiokarma |
#81
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let's make DTV McDonald happy
So with the covid lockdown keeping me in the basement I've been going after partially done early color projects....
Where to begin on this? Shortly after my last post Benman offered to trade his CBS 205 for my 21CT55... looking carefully I came to the conclusion that I'd be trading for the same chassis in a bigger less attractive cabinet with a smaller CRT and I'd be trading a set that needed an alignment and refinish for an unrestored chassis that might also need an alignment and decided to fix my 21CT55 (which has been working and looking excellent for a year and a half now and I should post that saga eventually).....one interesting thing on the 21CT55 was it didn't need an alignment...All it needed was the off tolerance IF resistors changed and the channel osc slugs retuned. That led to me to pull nearly all the decent 6AN8s out of the CT-100 to replace all the weak shorted specimens in my 21CT55....the CT-100 sat dark since then with the tubes missing (and eventually a bag of swapmeet 6AN8s sitting on top).... Late last week another slug cracked on my Moto 21CT2B so while I wait on another chroma bandpass coil from eBay for it I bounced over to the CT-100. After getting a fresh crop of 6AN8s in it replacing the 6DE6 somebody placed in the 2ND IF with the correct 6DC6, changing off tolerance resistors in the 2ND and 3RD IF, and changing the paper cap in the tone circuit the hack that recaped it left I was easily able to get it to pass decent chroma through the IF... there's some chroma/sound crosstalk in the lumina channel I need to fix yet (If resistor replacement in the IF I've since done hasn't fixed it) but it is now watchable. I'm almost done going through the IF resistors. I also plan to replace the 1-2 remaining original leaking coils in it and the other peaking coils with the same ones I used in my 21CT55 (the ones miniman82 recommends from digikey). Whoever put in the somewhat random assortment of peaking coils in this set also did a lot of sloppy J-hooks (sometimes a J to another J to finally the cap lead) sloppy soldering and other baloney that makes me question their competence to select correct peaking coils. I plan to go through and change all off tolerance resistors in the color and video stages as well as the HV and to change the doorknob capacitors out before they can fail... If progress holds I'll have this set done soon.
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 Last edited by Electronic M; 05-04-2020 at 02:37 PM. |
#82
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Good work, Tom.
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#83
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Nice!
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#84
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Very nice. You should turn off the lights and fill the VF with the image(s).
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Personal website dedicated to Vintage Television https://visions4netjournal.com |
#85
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Well I'm close to calling it done. I've gone through every resistor in the set (except for a few in the sync separator and sound because those stages are doing fine), changed most of the peaking coils except for 3 50s butterscotch colored ones on the video amp boards that aren't the lousy chalk ones and in the process I have fixed 70% of the lousy J-hook connections whoever did the original recap haphazardly moused in. I also changed the HV doorknob and the large convergence doorknob capacitors to newly manufactured ones I bought off mouser and digikey a couple years ago. I discovered someone else changed the vertical convergence transformer over to the more safe/reliable reproduction (the 15KV leads with silicone insulation definitely weren't around in the 50s).
The chroma osc has drifted a few times on me during long opperation and required tweaking to dial in... I'm almost done with a 1.5 hour shake down run and so far chroma sync has been solid so I guess that problem has been licked. I got the convergence good over all but the vertical convergence especially the top just doesn't want to be perfect. Also annoying is despite it supporting a nice bright picture commercials and scenes where there is a static image that is more than 80% bright white the HV says and the focus goes out into left field till image content averages darker (but IIRC that is normal behavior for these sets). Picture is excellent. When I went to install the channel knob I was surprised to discover my CH13 modulator came in on CH10!...I was gearing up to align the modulator when I came upon 3 pleasant surprises... First the set was actually set to the CH13 strip and the channel plate knob wasn't indicating correct. Second the set came with UHF strips for CH15, 33 and 35, third a spare monochrome set version of the tuner that was sold to me as a 21CT55 tuner had a CH22 and 36 strip in it...I pulled the both and put the 22 strip into the blank spot in the CT100. I figured out the channel indicator knob was put together wrong and reassembled it properly. There are no UHF channel tabs on my knob and I'm debating trying to create some....I have at least 2 more channel indicator knobs (one has UHF numbers for the wrong channels)...I need to see if I happen to have anymore with the right UHF numbers. I'm wondering if I should do more with the horizontal system...the cathode current is around 115mA (I can't find a spec to know if that's good or bad....the grid waveform has its top clipped...that issue gets better with the drive cranked up to max but I have to dial the drive down some to prevent getting a drive line. The flyback settles at about 90f on the HV winding, and 130f close to the core on the center winding after prolonged opperation...What do you think? I also was able to touch up the missing toner lacquer on the feet... because it was patchy I used Howard's and steel wool and lot of elbow grease to remove the lacquer remnants from the feet in a clean line then I resprayed the feet with fresh toner...it isn't perfect, but I don't want to do a full refinish and it looks a heck of a lot better than it did before. I don't know if I should fix it more or call it done and haul it up to my display room..
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
Audiokarma |
#86
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More pictures.
I'm thinking about adding a 12V computer fan run off rectified 6V heater line (I did this in my 21CT55) to blow on the flyback and cool it...
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#87
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Another thing I'm on the fence about is dismantling the CRT shroud and cleaning the ultor ring insulator. For the first 2-10 min on it makes a rain storm of small HV crackles around the insulator then goes silent upon warm up....I prefer to handle something as delicate and rare as a 15GP22 as little as humanly possible but I'm hesitant to leave things in this state...
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#88
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Take it apart and clean the crt. I have found that a build up of film on the inside of the plastic insulator at the front of the tube and on the glass can cause that static crackle and in turn interference in the video. Removing the crt on a CT100 is a piece of cake. Go for it.
Nice work Tom. I am in your camp about "J" hook repairs. Removing the leads from the terminal lugs is so easy if you have a pump driven de-soldering machine and you know how to wiggle and create a cold solder joint.
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Vacuum tubes are used in Wisconsin to help heat your house. New Web Site under developement ME http://AntiqueTvGuy.com |
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