I found this one semi-locally. Missing knobs but everything else appears to be there. I don't have a real way to test, but the getters on the CRT at least appear to be OK. I'm going to try to get this thing working little by little starting with the horizontal sweep section and go from there. Lots of paper/wax capacitors in here! You all think I should try to maintain appearance and restuff the paper caps or just say screw it and put the modern yellow ones in there? I don't see where any components have been changed on the bottom of the chassis, and most of the tubes appear to be original Westinghouse (mostly rebranded RCA and GE) except the horizontal output tubes and one 5U4. One question: Is the chassis copper plated or is it just some sort of copper colored coating?

Serial number MW005779, chassis number ME000552

I found this one semi-locally. Missing knobs but everything else appears to be there. I don't have a real way to test, but the getters on the CRT at least appear to be OK. I'm going to try to get this thing working little by little starting with the horizontal sweep section and go from there. Lots of paper/wax capacitors in here! You all think I should try to maintain appearance and restuff the paper caps or just say screw it and put the modern yellow ones in there? I don't see where any components have been changed on the bottom of the chassis, and most of the tubes appear to be original Westinghouse (mostly rebranded RCA and GE) except the horizontal output tubes and one 5U4. One question: Is the chassis copper plated or is it just some sort of copper colored coating?

Serial number MW005779, chassis number ME000552


I hope you can restore this TV to its peak condition, as this was the first color television receiver to be marketed in the United States. (You can test it if you have a VCR, DVD player, or a cable box.) I did a Google search on the model number and found a site which mentioned the price of this TV was just under $1300. This meant not many such sets were sold; in fact, most of the sets Westinghouse manufactured that year did not sell for that reason and, not surprisingly, there was very, very little color programming on the 3 networks (NBC, ABC, CBS) at the time, so even folks who owned this particular TV did not see much as far as color shows went; that is, the new Westinghouse TV would display a picture, but in b&w.

Color TV was definitely a status symbol in the 1950s, with most existing TV stations not yet equipped for color telecasting, so even if you could afford this Westinghouse small-screen roundie TV, you would be watching mostly b&w programming on a pitifully small (by today's standards) round screen.

Color telecasting did not "take off" in the US until the 1960s, and even then the sets were prohibitively expensive for most folks, so most stayed with their old reliable b&w TVs; this did not change until later on that decade. Think of when the first flat-screen HDTVs went on the market shortly after the DTV transition of 2009. These sets sold for well over $1000, with very little HD programming available. Now, nine years after the introduction of HDTV, flat-screen TVs, even large-screen models, can be had in some cases for under $100. Early color TV went almost exactly the same route. By the 1960s into the 1970s, color boomed in the US; more and more homes were getting color, relegating their old b&w TV to the basement or rec room or discarding it if the CRT went bad, or the set had developed expensive repair problems. This also is the story of the evolution of today's flat-screen HDTVs and how they have completely replaced analog sets, but that will be material for another thread.

BTW, I am not sure where or even if you will be able to find a set of knobs for your Westinghouse TV. You could put an ad for such knobs on VK's own classifieds section; that failing, I would search eBay or Craigslist to see if one or more of these knobs turn up there. I would try to find a set of period-correct knobs, as this TV was the first mass-produced US color set; it would not look right with just "any old" knobs on the control shafts.

Wow ! Talk about being LUCKY.. As with any/all "1st out of the Box 15" color sets, you likely can count the survivors on the fingers of one hand... Well, maybe not quite THAT rare, but these guys ARE pushing 70 years old (Gulp !) they were temperamental things when new, & spare parts TRULY are "Unobtainium"... But, Man-Oh- Manischevitz getting to have/see one of these actually WORK would be worth ALL the hate & discontent you'd have to endure... IMHO, anyway.

Actually the westy has around 26-28 survivors known so you'd need all your fingers'n toes plus a friend with about half theirs. It is the second highest surviving 15" color to the CT-100 of which somewhere in the neighborhood of 200 still exist.
3rd place seems to be RCA model 5 prototypes at 12 then a gradual slide down to 0-1 known for some. http://www.earlytelevision.org/color_database.html

It is great that more are coming out of the woodwork. The more that we can preserve the better. :thmbsp:

Absotively ! Also glad to get clued into the relatively HIGH number of survivors. Have wondered about someday venturing to greater Nashville, & hitting up the sort of "Downmarket" type antique stores & seeing if any odd ball "Goodies" lurk therein.... Nashville had a LOT of well paid "Industry" types, that were the kind of folks that would buy all the new type "Toys" like color sets, transistor stuff, VCRs, fancy cars, all like that. Its an ENTIRELY different world than we were, here in hardscrabble Greater Bugtussle...

Erich, I am very happy for you (and envious!). Glad that you found this set and it truly deserves a restoration. I also hope that the 15GP22 is good as well. Please, keep us posted.

I got the power supply chassis OK with new capacitors in place of the multi-section electrolytic, but connecting it to the main chassis only found more electrolytics in need of replacement (a B+ dropping resistor started smoking right away). I'm going to have to remove/replace the multi-section capacitors on the main chassis one by one and do a restuff so I can avoid that kind of problem later and concentrate on getting the sweep sections going.

I was reading the other long thread here about the same model TV and saw something about magnets for static convergence. The three screws on my set don't have any kind of magnet on the end and don't look like they ever did. What is this magnet supposed to look like?

These are the 6-32 threaded magnets that are about 2 inches long for the static convergence.

I’m about to post an update. We are in need of one to finish our restoration.

In that case I'm probably OK. The threaded rods are in fact weakly magnetic. I thought it had to have an actual magnet on the inner end.

So far I restuffed the FIVE electrolytic cans on the main chassis (I thought there was four, but then another B+ resistor started smoking and I found the fifth can). Then I powered up the set without horizontal output tubes and verified the sweep oscillators. I had to replace the coupling capacitors at both the vertical and horizontal output tube control grids since there was excessive positive voltage on the grids. Next I installed the horizontal output tubes and everything seemed OK. Lastly I tried installing the CRT assembly back in to see if I can get a raster, but no go. I found normal voltages on the CRT cathode, G1 and G2 and some semblance of high voltage (slight static cling holding paper to the CRT faceplate). No abnormal light show in the CRT neck, either, so that's still a really good sign. Next step is to get a proper HV probe so I can verify the HV, focus, and convergence voltages.

One of the candohm resistors decided to short to the chassis, so I need to find a solution for that. It feeds power to the sound section, so for now it is disconnected.

EDIT: Actually my G1 voltages are a bit high, but that should cause the CRT to go to maximum brightness anyway. Will have to replace coupling capacitors in the chroma adder section for this. Had to go to the Sams folder to find CRT electrode voltage readings.

I got a HV probe so I could trouble shoot the low HV. One of the doorknob capacitors is bad (measured about 1MEG resistance leakage, no good). When I pulled the plate cap on the second 3A3 the HV went from 6kV to 14kV. Repairing this should get the HV where it needs to be. Also during testing the focus control started smoking and got destroyed. I found out I have the dreaded vertical convergence transformer problem which caused the focus control to burn out. So I have three things to take care of before I can move much further.

I'm going to experiment with graphite and epoxy and see if I can repair the focus control. It looks like it's going to take quite a few attempts before I can get something I can use to replace the resistance track. Next I will see if any more reproduction convergence transformers are available. The doorknob capacitor is a bit expensive but available, so no problem there.

I have another idea for repairing the focus pot. The challenge is that the pot can dissipate up to a watt according to some rough calculations. The resistance track is just a bit over 4 inches long and about a quarter inch wide. I need something that can take the heat. I ordered a sheet of .020" phenolic material, now I need to find some way to get a resistive material to adhere to it. Maybe try graphite in a clear lacquer.

In that case I'm probably OK. The threaded rods are in fact weakly magnetic. I thought it had to have an actual magnet on the inner end.

If you have a bad screw magnet for a CT-100 or similar, there is an easy fix, which I used.

Just find a small ceramic magnet and break it into various size pieces. Set the
defective screw at a convenient spot, then try pieces at the OUTER end
of the screw until it more or less converges. Then glue it on, and screw the screw until its exactly right. Easy.

Well I have results and some more problems to overcome. I can get picture and sound. I have no color sync at this point. I need to repair the broken coil plug on the hue control and see if that helps. It seems to have normal signal flow in the chroma section when checking with a scope, it just won't sync up. I can get on both sides of the lock point with the color hold control, so that is likely OK.

Next is the HV supply. I was able to repair the damaged focus pot. I made a new resistance track using thin phenolic board and pencil lead. I applied the pencil lead to the roughed up surface of the phenolic strip until I got the correct resistance value. I then installed it in the potentiometer housing. It seems to hold up even when constantly adjusting the control. I had to replace two doorknob capacitors as well. Now I get 27KV and can't regulate it down to normal. Possibly one of the high value resistors is out of tolerance.

Last on the list is the vertical convergence transformer. The reproduction parts are no longer available so I will have to rewind it myself at some point. For now I have wired around it for testing. Of course the convergence is off, but at least I can see how the rest of the set is working.

The CRT may be weak or the kind of picture I'm getting is a result of the excessive HV. It's better than a completely dud tube at least.

I've used india ink for DIY high-value resistors. It would probably work for potentiometer elements too, depending on wattage rating.

Yeah, that was one idea I tried early on for the focus pot repair, but the India ink I tried was a bit too conductive. I laid out a strip on paper and got less than 100K resistance. Now I was able to use it to repair the red screen pot since it arced and burnt at the end of its track where it was riveted. The resistors are available at Mouser, but they're about $20 a piece. I have only one meter (Keithley 196) capable of measuring resistor values this high, but it's in need of calibration for the resistance function and I'm not sure how accurate the readings really are. I calculated the voltages I should get from the schematic, so I'll try making measurements later to see where I'm losing voltage. The voltage at the 6BD4 grid is low (200V, needs to be closer to 300-400V) to get it to start conducting and lowering the HV to spec.

Well I have results and some more problems to overcome. I can get picture and sound. I have no color sync at this point. I need to repair the broken coil plug on the hue control and see if that helps. It seems to have normal signal flow in the chroma section when checking with a scope, it just won't sync up. I can get on both sides of the lock point with the color hold control, so that is likely OK.

Next is the HV supply. I was able to repair the damaged focus pot. I made a new resistance track using thin phenolic board and pencil lead. I applied the pencil lead to the roughed up surface of the phenolic strip until I got the correct resistance value. I then installed it in the potentiometer housing. It seems to hold up even when constantly adjusting the control. I had to replace two doorknob capacitors as well. Now I get 27KV and can't regulate it down to normal. Possibly one of the high value resistors is out of tolerance.

Last on the list is the vertical convergence transformer. The reproduction parts are no longer available so I will have to rewind it myself at some point. For now I have wired around it for testing. Of course the convergence is off, but at least I can see how the rest of the set is working.

The CRT may be weak or the kind of picture I'm getting is a result of the excessive HV. It's better than a completely dud tube at least.

Did you contact John Folsom? He may have a VCT. SEE THE BOTTOM OF THIS LINK: http://www.videokarma.org/showthread.php?t=270450&page=5

Yep, already tried emailing John Folsom, he replied that he has no more transformers available. The one in my set has either shorts or leakage from secondary to either ground or the primary. This one doesn't look fun to take apart or rebuild. Lots of varnish and many thousands of turns of fine gauge wire. I probably won't get an exact turn count out of this. Also looks like the laminations are stacked in alternating directions, so they'd have to be pried off one by one.

Sure is nice to see what certainly appears to be a good CRT! Major obstacle overcome. Thanks for sharing your progress and pictures.

The apparently weak CRT turned out to be a wiring error on my part in the color video amplifier section. I had a coupling capacitor essentially shorting blue and green signals together as well as shunting the green signal to ground. Correcting that as well as going through a few adjustments in the chrome section allowed me to get a color picture at last. The set still does not like displaying very bright scenes, but these sets probably never got really bright pictures to begin with, so I will just keep the brightness down. Color lock is still a bit weak. Still need to come up with a solution for the vertical convergence transformer to get this working like it's supposed to.

Very nice improvement.

Very nice improvement.

And "getting there". I will admit that as a young adult, I really looked down on the round color tube. To make it even more disgusting, I had no knowledge of the 15GP22 Kinescope! Now, I can really appreciate seeing one displaying a color image. So very cool.

I remember the hype about "Rare Earth" phosphorus and thought that this was a remarkable discovery. But red became Chinese Red, not blood red if I under stand correctly. Seems that the 15GP22 and 21AXP22 were the cat's meow colorwise?

Wikipedia has a pretty good writeup about CRT phosphors. The original red wasn't very efficient to begin with, then 80% or so of the electron beam current never got past the shadow mask anyway to even light the phosphors. From what I have read, the original NTSC phosphors were used in the 15GP22, 15HP22, 19VP22, and early production 21AXP22 tubes. The later reds had a bit shorter wavelength and so appeared a bit more orange. The green phosphor was changed somewhere down the line as well, but I don't know when (probably starting with the 21CYP22). The original green is actually the same as the P1 used in old oscilloscope CRTs. Later color TV tubes first used cadmium doped phosphors, then later on the rare earth (yttrium and europium I think) phosphors.

The overall impression I get having read various articles about the subject is that the 15" color sets really were the wrong product at the time. This is when 21" B&W sets were common, and you were going to pay lots of money to get what is effectively a 12" round CRT color picture. Add to that the weird and expensive construction of the 15GP22 and that's probably why these sets were sold at fire sale prices soon after being introduced. The CBS 19" CRTs seem to be even less common than the 15" ones. It took RCA with the 21AXP22 to get color TV sales off the ground, and it still took over a decade for color TV sales to reach 50% of total.

Well the 15G development started around 1950-52 and at the time 15" was the standard screen size so it is understandable why they picked it.

The 19" color tubes only had a few months before being obsoleted by the 21" tubes.

In that case the 15" tubes just ended up obsolete by the time they were ready for the market. I'm curious as to why RCA thought the best thing to do was use the separate internal faceplate in the 15GP22. It's either flat or very nearly so which introduces pincushion distortion. Maybe they thought they'd get best results getting phosphor dots on that kind of faceplate?

This set has been a real interesting experience for me. I never thought I'd run across something like this becoming available, much less with a good CRT.

I believe the flat internal phosphor plate was used in the 15GP22 due to technology being unavailable to create a stable curved shadow mask. The flat mask could be under tension to prevent deformation with temperature. A domed mask had to be mounted on temperature-compensating mounts that moved the mask back or forward slightly depending on temperature (and resulting contraction/expansion) in order to maintain color purity.

Yes, and in addition I believe that the phosphor dots were merely silk screened on the flat plates used in the 15GP22. The photo process to deposit the phosphor on a curved surface, using the shadow mask as a “negative” for exposure had not been perfected when these tubes were manufactured.

jr

"merely silk screened" doesn't quite describe it.

Zworykin and Morton describe the process in "Television" 2nd Ed. 1954. The description seems to be adapted from a 1951 paper by Barnes and Faulkner, but I believe it is the same as in the 15GP22.

Summary:
Produce the original image for etching the mask by exposing a photographic plate to a fine wire grill twice, with a rotation of 60 degrees between exposures.
Careful processing and copying reproduces a negative optical mask with round dots instead of diamond-shaped.
Expose a thin super-nickel sheet coated with photengraving enamel through the negative.
Wash away the unexposed enamel and etch the exposed metal to form the apertures with sharp feather edges.
Heat this mask and attach to the support frame while hot, so it becomes under tension.
For phosphor patterning, prepare a stencil from the mask:
[One stencil will be used for all three phosphors, with a precision displacement between applications.]
Place a Kodalith plate at the screen position with respect to the mask, and expose with a point-source carbon arc lamp placed at one gun position.
Develop the Kodalith plate.
Sueegee a protective coat of lacquer and wax onto the developed plate.
Coat with photosensitive gelatin emulsion, and expose through the plate onto the emulsion with a carbon arc lamp.
Wash away the unexposed gelatin.
Transfer the wet stencil from the plate to printing mesh and dry it.
Squeegee the phosphor suspension (phosphor powder in ethyl cellulose and amyl alcohol) onto the flat CRT glass screen.
Remove the stencil and clean it.
Allow the CRT screen to dry.
Bake the plate to remove the ethyl cellulose.
Repeat for the other two phosphors, with the stencil precisely positioned.
Bond the phosphors to the plate by misting with potassium silicate solution.
Float a nitrocellulose "blanket" onto the plate and evaporate an aluminum layer onto it.
Finally, bake to remove the nitrocellulose.

The thing to note is that the shadow mask was used as a negative, but with the intermediate stage of producing a silk screen instead of direct deposit of the phosphors.

Sheesh, its a wonder they ever got any 15GPs out the door w/all THAT going on...

Wow! thanks for the process details... incredibly more complex than I had imagined when I heard that the phosphor had been “screened” on to the plate. :thmbsp:

jr

I'm sure there were many more details to the production apparatus that you wouldn't guess unless you had it to examine. For example, the book mentions that a special technique (exactly what, they don't say) was used that held the silk screen in contact with the glass plate while squeegeeing so that it wouldn't stretch and distort the pattern.

This is the kind of thing that makes me laugh at people who ask why we can't rebuild the Saturn V rocket today to go to the moon again. It's because the tools are gone and those who developed the secret sauce for their use are too. So we have to start from scratch. Now, we may build something much better, but we still are starting from scratch.

I didn't take many pictures of the focus pot repair, but this is what I have. I got about 6.5MEG overall resistance which should be close enough. The difference between 5 and 6.5MEG is a few quick strokes of pencil lead, so that was my stopping point after having to remove material several times. I drilled out the two rivets holding the outer terminals to the by housing and used small screws to install them after placing the new resistance strip in. So far it has held up to frequent adjustment. Seems that it is necessary to tweak the front panel convergence and focus adjustments almost every time the set is turned on, mostly the convergence control.

"merely silk screened" doesn't quite describe it.

Zworykin and Morton describe the process in "Television" 2nd Ed. 1954. The description seems to be adapted from a 1951 paper by Barnes and Faulkner, but I believe it is the same as in the 15GP22.......

Mullard made a film about colour CRT production in the UK. I'm sure techniques had been refined since 1954 but the basic principles are unchaged: https://www.youtube.com/watch?v=0Qd4IX3wpZk

old_tv_nut said:
"This is the kind of thing that makes me laugh at people who ask why we can't rebuild the Saturn V rocket today to go to the moon again. It's because the tools are gone and those who developed the secret sauce for their use are too. So we have to start from scratch. Now, we may build something much better, but we still are starting from scratch. "

Not just stuff as complicated as a moon rocket. Lot of knowledge about older valve and semiconductor manufacture is also lost. And much else besides. Even if it's all well documented, the formal term for "secret sauce" is tacit knowledge, or tacit skills. The stuff that isn't in the books, often passed on by direct experience. Here at VK and other vintage forums we are helping to keep those skills alive.

https://en.wikipedia.org/wiki/Tacit_knowledge

Thanks for the link. Most complete video on the subject I have seen.

Lot of knowledge about older valve and semiconductor manufacture is also lost.

As an example, who is rebuilding CRTs now that Hawkeye closed???

As an example, who is rebuilding CRTs now that Hawkeye closed???

Pretty much nobody, as far as anyone knows, unless you have a heavily modified DeLorean someplace. :tears:

At the risk of taking my own thread off topic, I really think the people who have been working with the rebuild equipment at ETF should practice on common B&W and color tubes first before worrying too much about pre war tubes and 15GP22s. Forget the metal cone stuff for now. Perhaps they have been, but all I hear about are attempts at rebuilding 15GP22s outside of that one monochrome tube that ended up with a 12V heater and one 21AXP22. Unfortunately their effort relies on volunteers at this point which limits the manpower available to learn and do the work and get to a point where those high value tubes can be reliably rebuilt at a reasonable price. Heck, I'd volunteer myself but I don't have the time or money to do it. I'm decades away from retirement and over a thousand miles away.

At the risk of taking my own thread off topic, I really think the people who have been working with the rebuild equipment at ETF should practice on common B&W and color tubes first before worrying too much about pre war tubes and 15GP22s. Forget the metal cone stuff for now. Perhaps they have been, but all I hear about are attempts at rebuilding 15GP22s outside of that one monochrome tube that ended up with a 12V heater and one 21AXP22. Unfortunately their effort relies on volunteers at this point which limits the manpower available to learn and do the work and get to a point where those high value tubes can be reliably rebuilt at a reasonable price. Heck, I'd volunteer myself but I don't have the time or money to do it. I'm decades away from retirement and over a thousand miles away.

I seem to have found a CRT rebuilder out there, Thomas Electronics at: https://www.thomaselectronics.com/repair-overhaul/

Don't really know what they will charge but it would be worth looking into.

I know myself if I didn't have to work due to retirement and/or if I hit the powerball or something, I'd like to join the ETF CRT rebuilding project to be trained and learn the process. Maybe it could turn into a business to support ETF and VK member's projects and so forth, I don't know. CRT TV's are still desired by people who play videogames so maybe like record players in the last few years, maybe CRT's and/or rebuilding will make a small but significant comeback. Sorry to hijack the thread too but I've often thought about this during quiet moments from time to time. I do agree we need to start with more common and modern CRT's at first and then progress to the older ones. Just my $0.02

Video of rebuilding report from this year's convention:

https://www.youtube.com/watch?v=ObHANbL0zB0

Well I have results and some more problems to overcome. I can get picture and sound. I have no color sync at this point. I need to repair the broken coil plug on the hue control and see if that helps. It seems to have normal signal flow in the chroma section when checking with a scope, it just won't sync up. I can get on both sides of the lock point with the color hold control, so that is likely OK.

Next is the HV supply. I was able to repair the damaged focus pot. I made a new resistance track using thin phenolic board and pencil lead. I applied the pencil lead to the roughed up surface of the phenolic strip until I got the correct resistance value. I then installed it in the potentiometer housing. It seems to hold up even when constantly adjusting the control. I had to replace two doorknob capacitors as well. Now I get 27KV and can't regulate it down to normal. Possibly one of the high value resistors is out of tolerance.

.


Eric, you have made unbelievable progress in a very short time. Take a bow!!! You have used a ton of creativity in getting things to work.

Regarding the pots you repaired. How did you get the graphite from the pencil lead to adhere to the phenolic board? You had mentioned using a certain type of glue, but I couldn't find the reference when I reread your notes.

Thomas electronics is a military supplier. They were mentioned in a thread here in 2014. There does not seem to be any progress in working with them, probably because of both price and the fact that people were looking for someone who could repair pyrex glass tubes. They might be an option if you have a regular glass tube and megabucks.

Eric, you have made unbelievable progress in a very short time. Take a bow!!! You have used a ton of creativity in getting things to work.

Regarding the pots you repaired. How did you get the graphite from the pencil lead to adhere to the phenolic board? You had mentioned using a certain type of glue, but I couldn't find the reference when I reread your notes.

Thanks for the kind words. I tried mixing India ink into epoxy but that didn't work, probably because the ink is water based and didn't mix well. Also, the epoxy didn't get hard enough to be able to be used as a resistance track, even without anything added. Next I tried adding ground up pencil lead to lacquer, but that didn't work either. I could have tried getting powdered graphite and adding that to lacquer again, but I didn't want to go through waiting for that to arrive, so I went back with my old idea of pencil lead rubbed onto a suitable surface. I initially used card stock for a trial and got a strip which measured almost exactly 5MEG, but since this part dissipates a bit of heat I didn't feel it was a good idea. That's when I started looking for a thin phenolic sheet. I got one that was .020" thickness and looks like thin PC board material. I roughed up the surface a bit with fine sandpaper and rubbed the pencil on it until I got close to the correct resistance. It really didn't take a whole lot of pencil rubbing to get there, and you could see light through it.

Thomas electronics is a military supplier. They were mentioned in a thread here in 2014. There does not seem to be any progress in working with them, probably because of both price and the fact that people were looking for someone who could repair pyrex glass tubes. They might be an option if you have a regular glass tube and megabucks.


I knew they were more of a military supplier but it seems from the literature they would take jobs, then again, as you pointed out, it could cost a lot. Even so, i figured it was good to mentioned them. Hopefully the ETF people will get a handle for this and perhaps in the future, there will be a small demand for it for others to pop up much like there is a small resurgence in vinyl records. I do see the point though where predicting the future is tough, but who knows, maybe once 3D printing gets more sophisticated. :scratch2:

Video of rebuilding report from this year's convention:

https://www.youtube.com/watch?v=ObHANbL0zB0

:thmbsp:Keep up the good work! If I hit the powerball, I'd like to be trained for this and join in.

Thomas electronics is a military supplier. They were mentioned in a thread here in 2014. There does not seem to be any progress in working with them, probably because of both price and the fact that people were looking for someone who could repair pyrex glass tubes. They might be an option if you have a regular glass tube and megabucks.
I spoke with them extensively back in 2014/15. They claim they are capable of rebuilding anything including Pyrex tubes although never provided evidence of this, and that's as far as it went. They would never commit to anything for any price. They basically had no interest in our community. Perhaps someone else could pickup the torch and try contacting them.

Darryl

I was in touch with them too a few years ago. Ultimately no result. Like Darryl, I don't think they're interested in folk like us.

With a place like that, would you really want to trust them with ultra rare, virtually irreplaceable, roundie CRTs? Given that they have never done them before, and don't even seem to care to try?

I spoke with them extensively back in 2014/15. They claim they are capable of rebuilding anything including Pyrex tubes although never provided evidence of this, and that's as far as it went. They would never commit to anything for any price. They basically had no interest in our community. Perhaps someone else could pickup the torch and try contacting them.

Darryl

Yeah, hopefully by the time when our demand will be higher, the ETF people can take care of us. I guess like with anything else, I'm sure Thomas would do it for the right price, everybody has their price as my father says. The thing is, it depends if we can pay for it. ;) I was always a big believer in "when the door is closed, God (or whomever/whatever you believe in) opens a window" but sometimes opening a window takes action on our part too.

Right now I am trying to deal with the failed vertical convergence transformer. I was not able to get a turns count due to damaged wires, and I gave up after unwinding over 6000 turns of wire which kept breaking due to corrosion. The primary was still good and I was able to get a resistance reading from that winding, but the secondary was open and I don't know a whole lot about it. The wire sizes on both windings measure the same (.003") which corresponds to a 41AWG wire. Knowing the wire resistance, winding resistance, and the approximate turns per foot of wire I get 2000 turns for the primary which would seem about right. Unfortunately the secondary resistance measurements given on the Westinghouse schematic are incorrect. Since the Sams folder on this model gives an RCA part number for this transformer as being the same as that used in the CT-100, I looked at that schematic and found very different resistance measurements as well as in the Sams folder on this set. I'm really not sure what to go with here. Also, the ratio on the secondary winding either side of the tap doesn't jive with what I know about the AC voltage requirements given on the 15GP22 datasheet. The datasheet gives a convergence/focus voltage ratio of 900:225, or 4:1, but the transformer looks more like 2.5:1 based on the resistance readings given.

Have you tried contacting Steve McVoy, who possibly could lead you to someone who has done this before and knows the turn count?

John Folsom and John Yurkon come to mind.

While waiting for information on the convergence transformer data I decided to do the IF and chroma alignment. The video/chroma was pretty close as-is with just a little adjustment needed. The IF is a different story, however. It had a narrow peak instead of the double hump broadband response shown in the service data. I was having problems with the cores sticking in the IF transformers and I ended up twisting the coil form in the second IF can. I had to remove the transformer and get the cores out and do the surgery on the broken wires. As of this morning I have the repaired transformer installed but not connected. The third and fourth transformers will have to have the cans removed so I can remove the metal clips that engage the cores and try to get them back into their places.

The marker in the center of the scope screen is 44MHz.
The second shot is the chroma response to the demodulator input and is pretty close to what is called for in the service information.

Here are the DC resistances of the vertical convergence transformer. These readingx are taken directly from a known good trans that I removed from my CT100 and replaced with one of the replacement transformers that Folsom had for sale back in the day. The original has been sitting on my shelf for about 10 years because I am saving it in case of a failure in one of my 15" color sets.

The resistance of the primary is 1060 ohms.

The secondary is 20,300 ohms center tap to one end.
and 8700 ohms center tap to the other end
with an overall end to end resistance of 29,000 ohms.

That equates to about 27,645 feet (5.23 miles) of #40 wire on the secondary at 1049 ohms per 1000 feet of wire.

Hope this helps in your winding effort in the event you are unable to obtain a replacement.

Good Luck!

Here are the DC resistances of the vertical convergence transformer. These readingx are taken directly from a known good trans that I removed from my CT100 and replaced with one of the replacement transformers that Folsom had for sale back in the day. The original has been sitting on my shelf for about 10 years because I am saving it in case of a failure in one of my 15" color sets.

The resistance of the primary is 1060 ohms.

The secondary is 20,300 ohms center tap to one end.
and 8700 ohms center tap to the other end
with an overall end to end resistance of 29,000 ohms.

That equates to about 27,645 feet (5.23 miles) of #40 wire on the secondary at 1049 ohms per 1000 feet of wire.

Hope this helps in your winding effort in the event you are unable to obtain a replacement.

Good Luck!

Thanks much for the information. I guess the Westinghouse and RCA transformers, although functionally equivalent, are actually constructed differently. Looking at the ad on the ETF website for the reproduction transformers, it says that 41 and 43AWG wires are used in the windings. My transformer had only 41AWG wire in both primary and secondary. The scan of the Sams folder for the Westinghouse shows secondary resistance readings of 3800 and 9200 ohms (although the scan is fuzzy in that area, so that's a best guess) whereas the RCA part as you measured is 8700 and 20300 ohms, respectively. The primary resistances are just about equal, however. My educated guess is the RCA part uses 43AWG wire on the secondary. 41AWG wire is about 1320 ohms/Kft and 43AWG is about 2140 ohms/Kft, quite a bit of difference. Using best guess turns per foot based on the location of the windings the primary is 2000 turns of 41AWG, and the secondary is 8700 + 17000 turns of 43AWG. For the Westinghouse part I get 2000 turns of 41AWG and 5750 + 12500 turns of 41AWG. Using the same insulation thickness the overall winding dimensions are roughly equal and just about fit in the E laminations.

The overall primary/secondary ratio looks to be different between these two if my assumptions and calculations are correct, but the tapped secondary ratios are nearly the same.

I don't know if I want to attempt this on my own or see if maybe Edcor or some other transformer company could produce this.

If you order them from a professional transformer company I'd be interested in 1-2 vertical transformers.
If John Folsom was ordering the reproductions from a reputable firm he may have proven exact specs from the company that you can use.

Thanks much for the information. I guess the Westinghouse and RCA transformers, although functionally equivalent, are actually constructed differently. Looking at the ad on the ETF website for the reproduction transformers, it says that 41 and 43AWG wires are used in the windings. My transformer had only 41AWG wire in both primary and secondary. The scan of the Sams folder for the Westinghouse shows secondary resistance readings of 3800 and 9200 ohms (although the scan is fuzzy in that area, so that's a best guess) whereas the RCA part as you measured is 8700 and 20300 ohms, respectively. The primary resistances are just about equal, however. My educated guess is the RCA part uses 43AWG wire on the secondary. 41AWG wire is about 1320 ohms/Kft and 43AWG is about 2140 ohms/Kft, quite a bit of difference. Using best guess turns per foot based on the location of the windings the primary is 2000 turns of 41AWG, and the secondary is 8700 + 17000 turns of 43AWG. For the Westinghouse part I get 2000 turns of 41AWG and 5750 + 12500 turns of 41AWG. Using the same insulation thickness the overall winding dimensions are roughly equal and just about fit in the E laminations.

The overall primary/secondary ratio looks to be different between these two if my assumptions and calculations are correct, but the tapped secondary ratios are nearly the same.

I don't know if I want to attempt this on my own or see if maybe Edcor or some other transformer company could produce this.

Forget about the resistance numbers on the Westy schematic. They are wrong. The correct numbers are on the CT100 Sams schematic. I have no first hand knowledge of the correct wire gauges, but I would go with the numbers on the ETF ad for Folsoms trans. What do you come up with when you measure the actual wire from your trans?

Yeah, I know the Westinghouse schematic numbers are wrong (1350 ohms for the secondary IIRC). Since the CT-100 part looks like it works in this set as well I'll go with the numbers I get based off of your information. I did measure a 1 foot piece of wire and got 1.3 ohms which corresponds with the 1320 or so ohms per 1000 feet of 41AWG. 43AWG should have been more like 2.1 ohms per foot. That's why I believe the parts were made differently.

My secondaries were open so I didn't have the benefit of getting a resistance reading off of the original part.

I was finally able to do the IF alignment after dealing with stuck and chipped cores and two transformers with broken wires. I think I got a pretty passable response after a lot of iteration. Hopefully the color will look and sync better now. I will need to order more capacitors so I can replace the remaining paper wax capacitors still being used. Also I will need to check out the horizontal oscillator since it starts becoming flaky after being on for a while, shifting frequency a bit then back again. I need to build a 3.58MHz crystal oscillator for aligning the demodulator section. That way I should be able to set up the 90 degree phase shift using a dual trace scope and be sure it's correct before installing the CRT to the chassis. That is the pain in the rear about this set... the CRT has to be removed from the chassis to do much of anything with it beyond normal adjustments.

Looks like I'm on my own as far as the convergence transformer goes, so I ordered one of those Chinese automatic coil winders and some 41AWG wire. This should make it easier to get a nice, tight, even wind and if the transformer ends up not working for some reason I can try again fairly easily. I'll first try winding the primary and see how close to 1000 ohms I get for winding resistance. That's a few days off right now. I also need to order more .1uF capacitors, and I will also get a 3.58MHz crystal oscillator for chroma demodulator alignment. My work area is in the garage, and with this 100 degree weather I'm not really doing much now.

I wish you success with the attempt.

Dumb question: why can't you use the internal 3.58 oscillator to do the 90 degree adjustment?

Dumb question: why can't you use the internal 3.58 oscillator to do the 90 degree adjustment?

Pretty sure Westinghouse didn't use a crystal referenced oscillator In that model so unless you are synched to a color burst it will probably drift off frequency.

Not a dumb question, because this particular set does not use a 3.58MHz crystal controlled oscillator like pretty much everything else. It's a bit more like a horizontal sweep oscillator AFC circuit controlling a reactance tube based off of the color burst and it actually has a control labeled "color hold". Guess that's why the alignment instructions call for an external crystal oscillator.

I knew it used an LC oscillator, but if you first adjust the oscillator and have it locked properly to an incoming signal, then it should be just fine for adjusting the 90 degree transformer.

By the way, I don't know why the designers used a tuned transformer to get a 90 degree phase shift. Better to use the transformer to get the impedance match needed (as they do), but not for the phase shift. The R-Y demod drive goes directly to the burst phase detector, so R-Y drive phase is stable at 90 degrees to the burst. Why not then use a simple RC circuit to get the additional 90 degrees for B-Y drive? It would not need tuning to obtain the correct and much more stable angle.

I have the winding machine here now. I did a test wind of one layer, 333 turns of 41AWG wire and it turned out very well. Now I'm waiting for the Kapton tape to get here. The machine did the 333 turns in well under a minute. I'm going to try the winding data I calculated for the Westinghouse part since it uses only 41AWG wire and see how it measures as far as winding resistance. It should not take a whole lot of time to wind the transformer with this machine.

If all goes well I will order some 43AWG wire and try to do the CT100 winding data as well. 43AWG wire is more expensive than the thicker, more usual gauges.

:thmbsp:

I measured the resistance of the 333 turn layer a bit later last night and it was 175 ohms. This calculates to 1050 ohms for the 2000 turns which is close enough to the original 1000 ohms.

Post a photo of the coil winding machine.

This is the same machine I have

https://youtu.be/7PXXoA3897M

I tried winding the replacement transformer, but my first two attempts were failures. The first one wound ok, but two of the free wire ends broke off and could not be retrieved. The second time I slowed down the winding speed and got most of the way through but started having problems with wire breakage because the wire was snagging on mold flashing on the edge of the wire spool. I did end up finishing the part and got the wire leads attached. One of the wires broke because the coil was too much of a tight fit to the lamination stack, so that one also became scrap. Now I need another spool of wire to continue. I did another test wind of the primary only and it seems to be ok, but I will need more wire to do the secondary. I'm new to this and am learning what works and what doesn't as far as securing the free wire ends and getting an even layer of wire to lay down. I also will make the bobbin a bit shorter than the core window so it hopefully will fit after all the windings have been laid down. I'll get this right eventually.

John Folsom was kind enough to give me a copy of the winding data for the replacement transformers that he had made available. Good news is my own calculations were close enough to have resulted in a working part if my first two attempts had succeeded. No 43AWG wire was used, so the winding resistances should be close to the Westinghouse part. Now I just need to wait for the new spool of wire to get here and start practicing with the machine again. I tried two more test winds of the primary which appeared to have turned out OK, but that one is easy since it's only a few layers of wire. The problems start with the secondary simply due to the number of layers of wire and insulating tape needed. Just a bit of unevenness from a wrinkle or air bubble seems to get magnified when winding the new layer over it. I probably won't get it 100% perfect, but I think I can get it close, at least enough to recreate the transformer. Apart from a few wax capacitors, the transformer is the last hurdle I have at this time to getting this set running again barring any unforeseen problems.

:thmbsp:

I did get the transformer working, at least for about a half hour before I heard the sound of insulation breakdown. I did at least get to see the results of the IF and chroma bandpass alignment I had performed. Much better detail and color quality than before. Back to the drawing board on that transformer, though. I was trying to do the convergence procedure when the transformer went bad on me, so I didn't get the chance to take any pictures.

I need to find something for winding layer insulation that has a bit of grip to it so the windings don't move around so much. Kapton is good for insulating the inside and outside of the windings as well as between primary and secondary, but is too slick to hold the individual layers. Double sided tape is too thick for this purpose as it will result in a coil which will not fit in the core window. I used fiberglass resin in a glass jar under vacuum for impregnating, it seemed to work but is too thick, also expensive since I had to throw away over 90% of the material afterwards. I could try something like good old Minwax polyurethane and hope it will cure all the way through. At least the unused portion can be saved. This has been an interesting, although a bit costly learning experience. I would like to try doing some audio output transformers later on down the road with what I have learned so far.

That winding machine looks expensive.

Yes or no depending on how you look at it. It sells for just under $600. It looks to do a pretty good job of laying down an even layer of wire. It's certainly not as good as a much more expensive machine, but for small production runs it will do fine. Materials and construction technique are just as important as getting an even layer of wire on the bobbin. The main weaknesses are the tensioning system and the wire guides, but those could be improved with a bit of ingenuity and work. The basic machine itself is pretty solid otherwise.

I did get the transformer working, at least for about a half hour before I heard the sound of insulation breakdown. I did at least get to see the results of the IF and chroma bandpass alignment I had performed. Much better detail and color quality than before. Back to the drawing board on that transformer, though. I was trying to do the convergence procedure when the transformer went bad on me, so I didn't get the chance to take any pictures.

I need to find something for winding layer insulation that has a bit of grip to it so the windings don't move around so much. Kapton is good for insulating the inside and outside of the windings as well as between primary and secondary, but is too slick to hold the individual layers. Double sided tape is too thick for this purpose as it will result in a coil which will not fit in the core window. I used fiberglass resin in a glass jar under vacuum for impregnating, it seemed to work but is too thick, also expensive since I had to throw away over 90% of the material afterwards. I could try something like good old Minwax polyurethane and hope it will cure all the way through. At least the unused portion can be saved. This has been an interesting, although a bit costly learning experience. I would like to try doing some audio output transformers later on down the road with what I have learned so far.

I developed a process for doing the vacuum impregnation which I detailed on audiokarma, have a look here:

https://audiokarma.org/forums/index.php?threads/diy-vacuum-impregnation-yes-you-can-do-it-at-home.859083/

Results have been extremely good, and I wouldn't hesitate to recommend this method.

Thanks a lot for the information! I was thinking of thinning the varnish with mineral spirits so it would be thin enough to get inside the windings and insulation. I first need to find a suitable tape for winding layer insulation. I used Kapton the first time around, but it's a bit pricey, has to be ordered in, and wires just slide all over it easily. Masking tape is too thick (5 mil), so I need to use something like regular old Scotch tape. The secondary is the tricky part since it carries 3KV or so of DC and up to 1KV of AC on top of that, and that's in very thin 41AWG wire.

I already have the equipment for doing the impregnation, just need to try again. I really didn't pull a vacuum as long as I needed to since the resin I used had a relatively short work time and I didn't want to end up with a big block of resin with a transformer in it.

Thanks a lot for the information! I was thinking of thinning the varnish with mineral spirits so it would be thin enough to get inside the windings and insulation. I first need to find a suitable tape for winding layer insulation. I used Kapton the first time around, but it's a bit pricey, has to be ordered in, and wires just slide all over it easily. Masking tape is too thick (5 mil), so I need to use something like regular old Scotch tape. The secondary is the tricky part since it carries 3KV or so of DC and up to 1KV of AC on top of that, and that's in very thin 41AWG wire.

I already have the equipment for doing the impregnation, just need to try again. I really didn't pull a vacuum as long as I needed to since the resin I used had a relatively short work time and I didn't want to end up with a big block of resin with a transformer in it.

Rather than thinning the varnish, try pre-heating it to reduce viscocity, and also making sure the transformer is well heated to expel moisture. Read through the procedure I linked to, the steps and heating were all based on trial and error - I tried a bunch of iterations to get to that. Long working time of varnish is a good thing. After you're done, unused varnish can be put back into the can and used later.

As for wires sliding all over kapton, why not use something like spray on 3M adhesive to make it a little bit tacky before installing it? Just a light dusting should be enough to hold the wires in place.

If one of the better materials to insulate between layers is too thick, maybe you could use it every other layer to get it's advantages and reduce thickness.

I can get 3M type 56 tape from Mouser, so I'll go with that on my next attempt. I attempted to wind the secondary without insulating tape between the layers because I was running low on tape at the time. The problem is the wire at the edges of the layers start moving out of place during winding of subsequent layers because there is nothing holding them in place. At least using tape between layers does hold the wires in place. There are 69 layers in the secondary, so keeping them in place without tape layers will be hard. Also I need to come up with a way to keep distance from the free wire ends of the windings and the winding layers themselves to avoid breakdown there.

At 8:00, this Chinese video shows the taping process. https://youtu.be/QsQ0GRR2yr8

In a former life, I worked in the Graphic Arts industry-We had a Gravure Printing plant. Trust me, go to a larger town, & locate a graphic arts supply house, & ask to see the 3M representative. They make tapes for every conceivable use & purpose-They very well could make one that is super thin. & you could be all set. Down here in the South, we have "Dillard's-If its Paper", but trust me, they'll have something. Another place to try might be a commercial electric/electronic supply house, say like W.W. Grainger's-They're nationwide, have an incredible supply line, often you go in there, tell the guy what you want/need, 10 minutes later, you're on yr way home., what you need in yr hot little hand.. ANOTHER place to try is McMaster-Carr, they have at least ONE example of EVERYTHING that was ever made-I ain't kiddin'... I can even remember the phone # of the Atlanta branch-404-346-7000, they work best if you have their catalog, but get one-Every Budding Mad Scientist/ol' electronics Junkie orta have at least one..Grainger's catalog is called the "Motorbook", I think you could order a electric motor that would run the Panama Canal lock gates.. Might take 'em a week or 2, but if you gots the Money, Honey, THEY gots the Time-And the Motor... Grainger's book is made out of Bible thin paper, McMaster-Carr's is a lot better to touch, feel, & use, to me..

Ordinary Mylar packing tape is a possibility, problem being cutting it to a custom width. I wonder if one could use a thin Cyanoacrylate glue to tack each layer at the ends? All you'll need is a couple tiny drops and that stuff will wick in a long ways. It will set almost instantly. Recommend a good hobby shop grade and not the cheap watered down variety store brands. Be cautious that if you heat CA glue with a soldering iron it can give off poisonous gas. Several years ago I got some yellow transformer winding tape from a place in Florida. It's available in any thickness you could want and they would cut it to custom widths. Back when I got mine they offered free engineering samples of off the shelf rolls.

I finally got the materials together to wind another transformer. This time I resorted to buying tape off Ebay since I was able to get it in 30mm width which was close to what I wanted. 1 1/4 inch would have been more ideal, but I think this will work. The winding resistances check out OK and there is tape between each winding layer this time. I did my best attempt at vacuum impregnating the assembled transformer with spar polyurethane. Just for fun I measured the inductance; primary is 7H and the overall secondary is 500H. Quite a bit of inductance there. I will put heat shrink on the secondary leads where they pass through a hole in the chassis. It's not the prettiest looking thing but hopefully it will work out OK this time.

Here is a picture of the finished transformer. For some reason my phone will not let me post pictures from the file storage so I could only get this one of the part as it is now.

Looks fantastic, fingers crossed that it works just as well!

Give it lots of time to fully dry - a couple weeks wouldn't be overkill, the varnish dries on the outside a lot faster than on the inside.

Nice work. Looking forward to the results.

Here are the other pictures I could not post last night. Go figure, wait a day and everything starts working again.

The convergence transformer is holding up OK. However, the front panel convergence control does not have enough range (not enough DC voltage), so I will need to replace the 100MEG resistor in the HV cage. Other than that it seems to work OK. Last thing I'll do is the chroma matrix adjustment procedure to get that up to spec.

I’m glad the VCT is holding up, good work! The color bars look better.

I turned it on this morning and what I noticed is I get inconsistent results from the HV supply. Last night the convergence was pretty bad, but this morning it was a lot better, and the front panel control is still maxed out for best convergence. I measured 22KV at the regulator tube and could not get it lower than that, so I believe the HV resistors in the cage are flaky. Also I have a problem with the red video amplifier that gives the impression of a weak CRT (looks like smear), but testing shows it's the video amplifier having a rising low frequency response. I have not replaced the electrolytic video amp feedback capacitors yet and that is a prime suspect for this kind of problem. The resistors and capacitors are on order as of now. Those resistors are really expensive; I had to go with 85MEG in place of 82MEG since that was all i could find, 100MEG is readily available. Those parts together are about $37.

A question for those who have experience with 15GP22 sets: Is it normal for red to go out of focus at a relatively low brightness? That's what I have, but other than that it doesn't show any other more usual signs of a weak gun like smearing or saturation. With normal video it doesn't appear all that bad.

I forgot, the red video amplifier problem is also intermittent and was not present last night.

The problem with the red is that if you have even a teensiet weak CRT, it clips on BOTH high and low sides. The low side clips at the DC restorer and the high side clips
at the CRT grid. Since there are no more good 15GP22s (and if there were, I would outbid you!) the only cure is to reduce the drive to the CRT until the red gun stops
clipping at its grid. This results in a dim picture.

To test this you need an SMPTE color bar pattern that generates saturated
red, magenta, yellow, and white, correctly adjusted for saturation, and a two-input
scope that does subtract of athe two channels. You also have to put the scope probes directly at
the red cathode and grid (both for DC correctness and also seeing if it clips at short transients).

You will likely be disappointed at the picture brightness.

But once done ... the total CRT current will be so low that the HV supply will be happy
as a clam.

I have a scope that can do the add/subtract of the two channels so I will try this once the adjustments and repairs are done and everything is working as well as possible. The red is such a deep color that it probably wouldn't be all that bright to begin with no matter what condition the CRT is in. As long as it gives a watchable picture it's OK with me, and I think it will after everything is done based on what I have seen so far. I know it won't run bright like a later set and even if I had a new CRT in it it still wouldn't run very bright. Most of the earlier monochrome sets weren't all that bright either, so it's OK with me. That's just the way these things were.

I replaced the two HV resistors and the 4uF video amplifier feedback capacitors. Checking the old ones found the resistors out of tolerance, and I never could get a steady reading off the 100MEG one. One of the capacitors also was bad and it was the one in the red video amplifier. Now I have normal range on the static convergence control, and the video amplifiers are back to normal. I'll have to do a lot of tweaking to get the convergence better than it is now, but I think I can get it close. I am having trouble getting good purity, on these sets there is a lot of interaction between purity, convergence, and focus. The video looks pretty good and if I run it a bit dimmer than a modern set like it should be it actually look really nice so in the absence of an actual CRT test I will declare this one to be good. I think the convergence would be considered OK by an average person who doesn't work on these.

Looks good.

While trying to improve the convergence last night the horizontal oscillator decided to lose lock and then went off frequency. Best I can tell is one of the mica capacitors is going bad since swapping tubes and checking resistors showed no problems there. I went ahead and ordered parts to replace all the mica caps in that circuit.

Also, the vertical centering control was having no effect, but the control had normal resistance. I checked the large capacitor on the top of the chassis and it was OK, actually measured 2200uF (marked 1000uF) with a bit of dissipation factor, but not too bad for an old part and still usable in a low impedance circuit like this. I finally found the problem, the wire going to the center tap of the centering control was never soldered from the factory and now had green corrosion. I cleaned and soldered the terminal, hopefully it will work when I reinstall the CRT.

While trying to improve the convergence last night the horizontal oscillator decided to lose lock and then went off frequency. Best I can tell is one of the mica capacitors is going bad since swapping tubes and checking resistors showed no problems there. I went ahead and ordered parts to replace all the mica caps in that circuit.

Also, the vertical centering control was having no effect, but the control had normal resistance. I checked the large capacitor on the top of the chassis and it was OK, actually measured 2200uF (marked 1000uF) with a bit of dissipation factor, but not too bad for an old part and still usable in a low impedance circuit like this. I finally found the problem, the wire going to the center tap of the centering control was never soldered from the factory and now had green corrosion. I cleaned and soldered the terminal, hopefully it will work when I reinstall the CRT.

I got the horizontal oscillator back to normal, also I think I have the color sync improved over what it was before. Both sections had flaky mica capacitors, the kind with the 6 color dots that normally don't give too much trouble. They tested OK on an LCR meter, but I'm guessing they didn't hold up with significant DC voltage across them. One was the 100pF capacitor across the variable cap in the horizontal oscillator, the others were the two 3900pF coupling caps from the burst transformer (hue control) to the 6AL5 phase detector.

Although the CRT seems to have good emission, I think it was a bit marginal in construction since I can't get good purity at the edges no matter what I do. The yoke ends up diagonal when purity is as good as I can get it, and that's how it was mounted originally before I took the chassis apart. I also seem unable to get the convergence right at the edges of the screen, probably for the same reason. I'm starting to believe that perfect is going to be the enemy of good here.

The color also looks better without the oversaturated red I had before. I did the matrix adjustments in the service data using a signal generator, so they are just a close approximation to using an actual color bar generator. Using color bars from a DVD the waveforms look reasonable, but for example checking the red video signal shows the yellow bar lower in amplitude than the red and magenta bars. I found similar results on the blue and green video signals as well. I think it's more likely the DVD video signal isn't providing an actual calibrated color bar pattern. It was a JPEG image I got from the web and is a pretty good approximation, but I have no way to know it's exact short of using a vectorscope and waveform monitor on the DVD player output which I don't have at this time.

Next thing is I'm going to run the chassis a bit each day or so to see how it holds up and start working on the cabinet which needs a lot of help. Also need to find a solution for the missing knobs.

I'm still running the chassis out of the cabinet, waiting on me to start stripping and refinishing the cabinet since I got in a bit of practice on a Packard Bell B&W cabinet at first and did OK, and now know how to get a smooth finish.

I finally found the color sync problem, it was due to flaky ceramic capacitors in parallel with the 3.58MHz oscillator coil. I do have what looks like a bit of ringing in the picture, but it's really not noticeable most of the time. The signal looks great coming from the video detector but has the ringing at the delay line, and it seems to be the 6BK5 line driver stage that has the potential problem, or at least it was designed with this kind of response.

I'm also going to try swapping the leads on the vertical convergence transformer primary and see if that helps get the convergence a bit better. The controls only make convergence worse, and perhaps inverting the polarity of the convergence signal will allow correct adjustment. This is the part I had to rebuild myself and it's possible I got the two lead colors reversed when I assembled the transformer.

That means removing the CRT from the chassis one last time to do this and check out the video and color amplifiers as well. Then I need to clean the tuner so it will work without having to rotate the shaft back and forth for a good picture. At that point everything should be up to par.

I finally found the color sync problem, it was due to flaky ceramic capacitors in parallel with the 3.58MHz oscillator coil.


Hooray!


I do have what looks like a bit of ringing in the picture, but it's really not noticeable most of the time. The signal looks great coming from the video detector but has the ringing at the delay line, and it seems to be the 6BK5 line driver stage that has the potential problem, or at least it was designed with this kind of response.


If the ringing appears at the input of the delay line (plate of the 6BK5) and there are no off-value components there, then it may be designed in, a result of the 3.58 MHz trap in the cathode. If you have a DVD with an Indianhead test pattern, you can look at the resolution wedge to see if the ringing frequency is the same as the chroma trap frequency.

Here are the pictures I was not able to post last night for some reason. The scope screen shots show a multiburst signal at the video detector and the input to the delay line.

Hooray!



If the ringing appears at the input of the delay line (plate of the 6BK5) and there are no off-value components there, then it may be designed in, a result of the 3.58 MHz trap in the cathode. If you have a DVD with an Indianhead test pattern, you can look at the resolution wedge to see if the ringing frequency is the same as the chroma trap frequency.

I really believe the response is designed in, the ringing goes away if I short out the 3.58MHz trap. Like I said, it's not all that pronounced under normal conditions and video material.

Nice color bars.

Nice color bars.

My thoughts, exactly!

My thoughts, exactly!

+1

Despite the ringing that is very good picture quality for a 66 year old color TV. I'd probably decalre victory right there in your shoes.

The overall color looks great!

I do wonder if a re-tweak of the chroma bandpass alignment might make the transitions crisper, particularly, less of the blue phase distortion between the green and magenta bars. But, the IF alignment could get into the act here too, so it's a can of worms that might be better left closed. The effects are not obvious at all on the live video, which looks very good.

I have begun the process of stripping the old finish off the cabinet. The only real challenge is going to be the fake burl sections on the front doors. The finish is alligatored, and there is too much damage for these to be saved. The only options I can think of are using vinyl decals or installing actual veneer. Unfortunately I'm not so free at the moment to just walk into a woodworking store and have a look around. Any opinions on what would be best here?

As far as the electronics, I messed with the convergence adjustments again and got a bit better result overall. About the only thing left is cleaning the tuner so it stops acting intermittent. Everything else seems to be remaining stable. This set would never make a useful daily driver anyway (nor would I expect it to be) since the picture is dim and small compared to pretty much everything that came after, so as long as it looks and operates half decent I will be happy with it as it is.

My cabinet has real burl-wood. https://visions4netjournal.com/wp-content/uploads/2020/04/37A59587-8B11-4597-9B3D-EA7B0997BE00.jpeg

If it was me, I’d stay away from decals. Nice image. May I ask the source? I’d like to try the image on my Westy.

Very good progress on your Westinghouse.

My cabinet has real burl-wood. https://visions4netjournal.com/wp-content/uploads/2020/04/37A59587-8B11-4597-9B3D-EA7B0997BE00.jpeg

If it was me, I’d stay away from decals. Nice image. May I ask the source? I’d like to try the image on my Westy.

Very good progress on your Westinghouse.

you mean the wreath? Its attached. The lower right magenta ornament
is hard to get right.

http://www.videokarma.org/attachment.php?attachmentid=200773&stc=1&d=1587769878

You beat me to it, the image was from this thread

http://www.videokarma.org/showthread.php?t=272376

My "burl" is definitely fake, I looked at it with a loupe and could see the halftone printing. I guess I'll go with real veneer if I can find some that is nice and flat.

Oh, you mean that you added the photo to a homemade video, played it on your set and took a screenshot? I can do that. I was thinking an actual video source.

Yes, I first took that image and added some areas on the sides to make it 640x480 then saved it to a USB drive. Then I used my digital converter box to display a still picture from that file. It's also how I do test patterns these days.