It's a good 15GP22 with low hours, a restored CTC2 chassis with a complete set of original RCA peaking coils, and a rooftop antenna picking up a true NTSC color signal. Here's a revisit to 1953 NTSC color via 51-year-old hardware.

http://home.att.net/~pldexnis/CTC2_how_it_works/Living_with_1953_Living_Color.html

That's beautiful!
Thanks for preserving something from the past!
Sincerely, John

"page cannot be displayed"??

That's REALLY somethin'-but stupid question-do roundies all "lose" so much of the picture? Or is that just a peculiarity of the early 15" sets? -Sandy G.

Sandy,
That set in the background is a 16:9 set showing a 4:3 picture so it looks like the picture is much wider but if you look closely you can see there are actually black bars on the sides.

(Site is working for me now)

Superb!

Simplistically, a 15GP22 is a dud for one of only two reasons: no vacuum and no or low emission. (Maybe that makes three?)

Anyway, the process to rebuild a no/low emission 15GP22 electron gun assembly is perfected and in place. Ditto the manufacturer of glass stems. Basically, rebuilding the gun means replacing the old filament and cathode with new ones.

Recently (the last year or more) effort was extended to connect a stem to an old, dud 15GP22 neck. This has been done although I'm not certain the technique is as reliable as, say, the rebuilding of the electron gun. But the process has been successfully demonstrated.

What's being done now? The archives have yielded a bit of vintage 15GP22 data covering the baking temperature and slew rate of that baking heat. They are different from what is done today. Finding a way to reproduce the vintage procedure is the present challenge.

As to the phosphor in air question, no one seems certain although the current thinking is that since the 15GP22 is aluminized, the phosphors may be protected from the air.

Let me say, that is a beautiful picture. Absolutely beautiful. Infact so beautiful it's almost on par with this girl i gave a crush on. :P

I'd love to own a Merril and an RCA prewar set.... Maybe some day... :)

Jonathan

Who knew that old sets like that could produce such great pix? Gorgeous and well done!
Tom

I'm thoroughly impressed with the work you are doing. These sets must be preserved, and you are showing that it can be done. Are there many around that just aren't worth trying to restore?

Is there any possibility of air hurting a non-aluminized phosphor? I thought phosphors are essentially oxides or sulfides (specially formulated rock), so I would guess air is not going to do anything to them. (Moisture might be another issue. Maybe oxygen can hurt the sulfides or sulfur air pollution can hurt the oxides?) Have there been any expert opinions on this? Were old B&W tubes tubes ever rebuilt just by replacing the gun and leaving the phosphor alone, and did this depend on aluminization? This would be a good indication that there is no problem.

Pete Regarding the colors on the CT-100 - As I'm sure you realize, the original phosphors will ALLOW you to get correct colors, but there are a lot of matrix adjustments that need to be correct too. (Also, all the tubes in the color section need to be good - a weak tube in one part of the matrix may leave you with "acceptable" but not correct results.) So far, no two CT-100s that I have seen, nor the early Zenith prototype I saw, got the same color reproduction. Have you put color bars in and attempted the matrix adjustments?

Wayne. Thus far, I've gone by the book aligning the color (all front-panel controls) -- except for the I gain, which is running nearly wide open. Re color bars: gated color bars seem to have a luminance issue when bounced against the same signal displayed on the digital set. Blue bars on the CT-100 appear to be near-saturation in order to view red- and green-hue bars.

The setup: (1) both sets adjusted for color picture from over-the-air broadcast. (2) switch from antenna to gated color bar gen. (3) bars on digital set appear normally; blue-direction bars on CT-100 appear normal; red- and green-direction bars very dim. Readjusting contrast and brightness brings up the end hues.

Any thoughts on the color bar anomaly?


I made special efforts to find and use all original inductors, especially those in the demodulator filters, to get as close as possible to factory-original, and was successful except for L42, which I don't think is an important factor anyway (it's in the dc path from the color afc to the reactance tube). Was very fortunately to have gathered a full set of the 'white' inductors, which are very prone to opening up.

My further plans include sweeping the chrom circuits for published specs to help get as close to factory-original as possible.

Pete,

Using gated rainbow for matrix adjustment can't get you there, because you need each color to have the correct luminance as well as chroma to see if the final R,G,B drives are correct. You can use the gated rainbow to check the phase (and maybe preliminary gain) of I and Q, but not much beyond that If you can get a generator or a DVD with regular color bars (White, Yellow, Cyan, Green, Magenta, Blue, Black), that is best. All is correct when the individual red, green, and blue outputs of the matrix are square waves. All the peaks (max and min) in one channel should be the same amplitude, but the three channels will have different amplitudes depending on how much drive the CRT requires to make white. With non-rare-earth red, this probably means red needs 2 times (or maybe more on the 15G) the drive of green or blue.

Have you ever seen a setup done with a blue viewing filter? This assumes the matrix is correct, and adjusts hue and chroma so all the bars containing blue have the same blue amplitude. If the matrix is not correct, tough! - the red and green will be off when the blue is correct. In the case of the CT-100, it's worthwhile to check all three colors, since you have internal matrix adjustments. You could do this check with red, green, and blue filters. However, if you have full matrixed R,G,B driving the CRT, you can check with a scope. This measurement (and adjustment) is not directly available on later sets that matrixed by putting Y to the cathodes and color differences to the G1's.

Regarding brightness of colors: When a true NTSC tube with nominal NTSC matrixing is used, the reds may be darker than a modern set. This is because the modern set overdrives the R-Y to make up for the smaller difference between the red and green phosphors. In other words, turning on the modern green is like adding a little red to the picture, so the R-Y gain is increased to make the red turn off a little more than normal. On strong red color, this goes too far the other way (because of the CRT gamma), so strong reds come out over-saturated and over-bright. How much of this you see depends on how much R-Y boost the particular manufacturer thought the phosphors should have for best flesh tones and average scene content. On the opposite side of the spectrum, the 15G should show more saturated and brighter cyans. This should be obvious on full color bars along with the more "green" green.

In PAL, and in HDTV, the matrixing at the camera is changed to get the right color-difference signals for the MODERN phosphors with a nominal NTSC electrical matrix. So, reds are no longer overly bright, but of course you can't get the purer green and cyan that you could with real NTSC phosphors.

Looks good, Pete.

Wayne,

Thanks for all the info.

I thought that I might in be trouble without an NTSC generator because, as you confirmed, of the constant luminance factor. But I hadn’t made a connection to the ‘blue filter’ setup procedure, or using a scope to check luminance of CT-100 RGB channels. Thanks for that tip. I’ll use an S-video VCR and a DVD player to generate a color bar signal, and then scope the RGB channels…

Pete, it may help to use a ture NTSC color bar signal source (foff air or from a generator), instead of the gated rainbow generator, which does not control luminance.

How is the red? you photos seem to show only blues and greens...?

Actually John, over-the-air programming with a lot of red was tougher to find than the predominately blue or green samples. I did find some fair examples of red from an ABC movie this evening and added a series of five pictures to the link.

Congratulations Pete! That picture looks wonderful. I had always wondered if decent convergence was possible on a 15g. That is amazing. :thmbsp: Even perfect at the far edges.

John

quote from Wayne: "...but the three channels will have different amplitudes depending on how much drive the CRT requires to make white. With non-rare-earth red, this probably means red needs 2 times (or maybe more on the 15G) the drive of green or blue."

Checked this out and added material at the bottom of this link under 'CTC2/CT-100 MATRIX ISSUES,

This is a new link.

http://home.att.net/~pldexnis/CTC2_how_it_works/Living_with_1953_Living_Color__matrix.html

Calibrate this tweak that: realigned the color and added some screen shots of NTSC color bars that should look better than previous examples on your computer monitor.

See the "CTC2/CT-100 Matrix Issues -- more data... " section at the end on this page:

http://home.att.net/~pldexnis/CTC2_how_it_works/Living_with_1953_Living_Color__matrix.html

Pete,

Great work in setting up the matrix!

As I understand it, your digital camera brightens the blues on the CT100 but not on your modern set. Interesting. I found that some blue/violet neon tubes do the same thing to my digital camera - had to underexpose considerably to get the color even close.

Does the gray scale also look bluer in the photo than to the eye? If your camera allows manual white balance, you could try balancing on the gray scale, and then take pix of the color bars and regular material.

-Wayne

Spent another three hours on the CT-100 color alignment challenge this Labor Day weekend, spinning around a bucket full of variables, including discovering how fine-tuning affects matrix performance, and came up with an improved screen shot of color bars at the bottom of the link.
http://home.att.net/~pldexnis/CTC2_how_it_works/Living_with_1953_Living_Color__matrix.html

Once you get to the blue only stage, you should be looking for equal blue luminance visually on the cyan and magenta bars. The tint control will set this. This should be your ideal tint point...for bars.

Modern monitors have a blue only switch for quick setups. Modern NTSC bars are also split field with a smaller sub-set of bars through the middle. With these bars, the larger cyan and magenta bars are tint set as before, but now the sub-set bars (also cyan and magenta, but about 135 degrees out-of-phase) should also be luminance equal (but backwards) to the point that their luminance visually matches the bar above it. Rotate the tint until the upper chip matches the lower chip and all four should match.

This is the quick way to set analog sub-carrier phase from multiple sources through a switcher.

Never having setup a CTC-anything this way, it seem like setting the tint to center and adjusting the innards with this as a reference point would be something to look at.

Hope I did not add more hours to your scope time Pete.

Dave A

I just wish I knew HALF of what you fellas have forgot about this stuff...History & stuff like that ,I know...This stuff, forget it. I'm all thumbs. I'm in awe...-Sandy G

Are you just adjusting background and screen controls, combined with convergence, to produce accurate NTSC color reproduction? Or are you working farther back in the color sync and demod-phase inversion stages?
Let me first say, there is a vintage procedure for adjusting the matrix that requires I and Q signals from a generator. I have not tried this procedure. I do not have a generator that can supply the appropriate signal, although DaveA has kindly offered to lend me his vintage generator, and so I can perform the procedure sometime in the future.
----------------------------------------------------------------
To begin, color sync and the quadrature transformer and the color burst signal path adjustments must be successfully completed. The set must be able to decode and provide a stable chroma signal to the matrix before it can be tweaked.

Next, purity and gray-scale tracking are set up, basically as published in vintage documentation, which I’ll annotate below, or at least my version. Grey scale tracking is relatively easy to accomplish and has been stable in this CT-100 (B8000194) once set.

Purity setup is similar to early commercial service procedures: move the yoke back, B and G screens down, R screen up full and make adjustments including to the color purity and field neutralizing coils, move the yoke back to standard position, etc.

For grey-scale setup, a CT-100 has RGB screen controls, G and B background controls, and in addition, B and G gain, which consists of a pot on the appropriate 12BH7 circuit boards (not a PC board in the CT-100). These initial adjustments are accomplished with a b&w signal; I simply turn down the Color control. An over-the-air mono transmission (no burst) is hard to find!

I’m just going to copy the notes I made for myself as a guide to this gray-scale task:

CONTRAST AND BACKGROUND DOWN (CCW)
BRIGHTNESS NEAR MAXIMUM
R, G, B SCREEN (GRID 2) SET LOW-LEVEL WHITE RASTER — NO VIDEO

W/MONO SIGNAL SET BRIGHTNESS AND CONTRAST FOR NORMAL

B, G GAIN SET NORMAL-LEVEL WHITE RASTER

SET BRIGHTNESS LOW

R MASTER, G, B BACKGROUND SET TRACK WHITE RASTER LOW-TO-HIGH VIDEO

Once the tracking setup gives a b&w picture that doesn’t add a hue to any setting of the brightness and contrast controls, I crank up the color control and assess the damage.

To review, the purity is set, the grey-scale tracking is set, the color burst amp, color AFC, quadrature transformer, color subcarrier level, burst takeoff transformer, and whatever, are all adjusted BEFORE the matrix is tackled.

There are no matrix controls to speak of. Everything is fixed. During restoration, each matrix resistor was checked and found to be in tolerance. So what gets tweaked and what do you look for? I feed an NTSC color bar into THE SET on channel 4. I do not tweak the screen controls. Ditto the background controls. With a modern dual-trace scope monitoring the green and red 15GP22 control grids and a blue filter to observe the color bars, tweaking consists of a combination of the hue control, the brightness control, the contrast control, and ever so slight touch-up of blue and green gain. I recently discovered that, on this set at least, the fine tuning plays a roll in the matrix drive signals, mostly the blue. There is no red gain because in a CT-100 that gain runs wide open to compensate for the low efficiency of the red phosphor.

[You may recall the earlier scope photos and elation over the red signal being twice the amplitude of the green. That’s because to get the same brightness from the inefficient red phosphor, it is driven with about twice the voltage as the more efficient green (and blue) phosphors. Vintage documentation predicted the modern scope display.]

What I haven’t detailed is how to interpret the scope and filter data into effective tweaking. DaveA has provided a rundown in an earlier post for modern video equipment. Basically with the CT-100, the scope display is used to monitor the amplitude, or height, of the color bars for equal amplitude. Complementing that is the blue filter that’s used to visually balance the intensity of color bars. Blue filter use is a common technique, but it assumes that the matrix for the red and green is okay. I have red and green filters on order. When I get them, I’ll be able to check the matrix for all three colors and tweak as needed.

Of course, all this assumes one is not color blind, although I guess one so afflicted could adjust a matrix fairly well using the scope technique. Sorta thinking out loud here…

The fact is, once set up, any little tweak of any operator control, let alone service controls, will throw off the matrix alignment. That’s why I used the ‘…bucket full of variables’ phrase. It’s frustrating in theory, but in practice, if the ambient light changes and the picture requires more contrast, you can crank up the contrast control a little. Although you are technically no longer aligned, for practical purposes the picture still looks absolutely great. You’ll still have no problem appreciating the wide 1953 gamut.

Those screen shots of ct-100 converged properly are simply amazing as expected!!!
:D :thmbsp: :banana: :lmao:
I really do wish there were more of these sets with extra CRTs readily available. I'm hoping a lost stash of CRTs will some day show up. I have given up on wanting one of these since CRTs or replacements not available. I'll keep you in mind if ever come across extra 15" CRT.

I just read a review on a Dell Plasma TV for $2599 dollars in newspaper & said set could not decode colors completely accurately. It's amazing what people are paying for crap these days.

:no: :thumbsdn:

Bobgary, I believe the waveforms you posted correspond to an old Hickok generator, which had full field bars, but not in the modern order according to luma level. Also, once things are reasonably close, it's much easier to check if these color difference signals are exactly correct by looking at the R,G,B waveforms (if available) or looking at the picture through colored filters, or turning off two guns at a time. (Professional monitors will send the blue-only signal to all three guns so you can see blue as monochrome.)

Pete, I don't have a schematic in front of me, but you said the matrix is all fixed resistors. I thought I recalled an "I gain" adjustment in there somewhere?

Isn't this how the modern sets do...the chroma and luminance signals are mixed before they get to the CRT? Seems like in most of the tube type sets the mixing actually occurs in the crt itself with the chroma at the grids and the luminance at the cathodes.

Pete, I don't have a schematic in front of me, but you said the matrix is all fixed resistors. I thought I recalled an "I gain" adjustment in there somewhere?
You're right about the I gain of course, it was set weeks ago and has never seemed to require further tweeking. And I probably shouldn't have thought of the matrix as only the nine discrete 1/2-watters that combine the +/-IQ and Y.

I wish you could all experience the actual video: There's a commercial playing for a Lilo&StitchII (sp?) DVD. The bug-eyed character in the commercial on the CT-100 has bright, intense, large lime-green eyes that pop off the screen at you. Interestingly, in an A-B comparison between the CT-100 and my 38-in. widescreen CRT HD set, there's no similiar effect on the HD set, although there may be setup issues to consider. Just came back from seeing the DVD at Target. The eyes in the print version were pale blue and didn't even appear to have been designed to draw attention --nothing like the TV ad to my eyes anyway. Now I'm wondering what the DVD image would look like on the Merrill. Na. Not worth the fifteen bucks to find out.

Isn't this how the modern sets do...the chroma and luminance signals are mixed before they get to the CRT? Seems like in most of the tube type sets the mixing actually occurs in the crt itself with the chroma at the grids and the luminance at the cathodes.

Yep - Several things combined to make solid-state sets go back to RGB cathode drive:
1) CRT's with unitized guns, where only the cathodes were separate for the three colors;
2) cheaper to have only 3 high-voltage video output transistors instead of 4
3) with ICs: definitely cheaper to do all matrixing to RGB in the IC - also, at this point, the chroma and luma gain controls could be electonically ganged so they go up and down together without changing color saturation when the "picture" control is turned.

I can't remember if I ever saw a design implementing a "picture" control with mechanically ganged "contrast" and "color" controls - anybody remember such a thing? :scratch2:

---

I can't remember if I ever saw a design implementing a "picture" control with mechanically ganged "contrast" and "color" controls - anybody remember such a thing? :scratch2:
The CT-100 and the 21-CT-55 (basically a 21-in. CT-100) both used a ganged pot assembly to control luma and chroma simultaneously. For some reason however a production change to the 21-CT-55 bypassed the chroma pot, leaving only the luma pot functional. The user color was a separate pot in all cases, of course.

Back to the drawing board. I located the vintage matrix alignment procedure that includes adjusting L141, the inductor in the hue control circuit. This is where a course adjustment to the hue control takes place.

These main and alternate procedures seem to use the old non-luma-progression color bars Old_TV_Nut referred to earlier, who must also be the one to ask this question: ten years ago I worked on military stuff that used multiplying DAC's to contol what amounted to audio-frequency-range levels; is that how the function is or was implemented in TV for audio gain, contrast, and whatever? Is it even a good question?

Pete,

Did I miss it in your description? There is one tweak in the demod, the I gain control, which will modify the amount of +/- I signal used by the matrix adders to generate R, G, and B signals. Just one more independant varable in the equation.

....ten years ago I worked on military stuff that used multiplying DAC's to contol what amounted to audio-frequency range levels; is that how the function is or was implemented in TV for audio gain, contrast, and whatever? Is it even a good question?

It's a good question. There were no such things as multiplying DACs until much later. The first ICs for the color and video sections [and audio] were all analog, and did gain control using Gilbert-cell analog multipliers, which could be controlled by a common DC voltage. By the way, this was easier to implement cleanly, since the video and chroma signals did not have to be wired all the way to the customer controls and back, and the DC voltage could be filtered to get rid of noise pickup.

[Start of brag] One of my favorite inventions is a three-way I did with two other guys at Zenith (for monochrome chassis), where we stacked Gilbert cells, and using a simple external RLC filter as a simultaneous lowpass filter, differentiator, and second differentiator, did contrast control, switchable gated noise reduction, and video peaking control, in one swell foop [end of brag].

...we stacked Gilbert cells, and using a simple external RLC filter as a simultaneous lowpass filter, differentiator, and second differentiator, did contrast control, switchable gated noise reduction, and video peaking control, in one swell foop. The more you think about it the cooler it gets :thmbsp:

Have been working on the restored CT-100 recently to prep it for display in my living room. After extensive tuning and testing, got it buttoned up a few days ago, including the screen under the chassis, a small fan near the back to aid in dispelling heat, and wood screws in the back cover.

I cleaned and polished the mahogany veneer, tightened four wing nuts that lock the cabinet lid, and then turned it on and damn, three minutes later the screen went dim.

Remove the back, then troubleshoot to find the second video amplifier (a 6AN8) causing the headache. Pitch it in the trash. Put in a replacement. Button it all up again. Get out the NOS fine tuning knob I’ve been saving for this occasion and, after first testing the installation procedure on a spare CTC2 chassis, crack the plastic on the new knob trying to install it on the restored chassis. Cuss. Mix some epoxy. Stick it back together, and use a worn knob for now.

Okay, all this sets the stage for what I’ve been working for since 1999, but intensely since last April: eyeball 1953 NTSC color!

I think it happened. After mocking the WB earlier on AudioKarma, WPIX channel 11 came through with (pun intended of course) flying colors! South Park. Never watched it. Some of my thirty-something acquaintances love to quote it. Don’t care about it. But what color!

Chrominance charts indicate the extended green capability of the 1953 standard. My eyes believe the green on the character’s hat is in that extended area of the 1953 spec. A simultaneous display of the program on a high-definition direct-view CRT receiver in the NTSC mode was strikingly less vibrant.

The HDTV serves as a standard — a stable source of color used in the initial alignment of the color AFC circuits of the CT-100 for example. During the past several weeks, I would adjust the CT-100 to match the colors of the HD set. Not the brightness of course, but particularly subtle pastels and varying hues of violet. It’s a darn fine HD television set. But for this experience, which reproduces a program on two different sets driven from the same antenna, the HD set displayed completely lackluster green hues for that character’s hat compared to the CT-100.

Yellow was also visually different. A suggestion of which appears as this guy’s mittens.

The color resolution of hdtv is supposed to be more than twice that of NTSC, so next time you should crank up a true HDTV signal on that hdtv set if you want to see the CT-100 get even more green... with envy ; )

...next time you should crank up a true HDTV signal on that hdtv set if you want to see the CT-100 get even more green... with envy ; )
The color resolution, screen acreage, widescreen 16x9, luma resolution, six-channel sound, brightness, and just plain digital stability of HDTV produces an awesome video experience. :thmbsp: One I never want to miss.

Books and charts say the color gamut is greater with 1953 NTSC, as I interpret them anyway. My gnawing itch wonders if WB11 actually transmitted the video with wide-enough gamut to make the effect I saw on the CT-100 vs. the HDTV. I wonder if the cartoon makers had their software set to 1953 NTSC. I wonder if the NTSC generator in my VCR is spitting out a color bar signal good enough to calibrate the CT-100. I wonder, as I wander…!

Oh well, only 63 more days to the next Rose Bowl. :yes:

Everyone uses VCR's for the RF modulation on channel 3 or 4! :) I can't remember the last time I used a VCR. :) Both my 630TS and CTC9 Felton has VHF tuners, and there are no VHF stations in my area. I was honestly going to buy one of those RF modulator boxes, but use my satellite receiver for the time being. Most newer model RCA directv boxes output full feild color bar by pressing the menu and info bottons on the receiver at the same time, and it has RF output too. I'd use my UHF to VHF converter for off air reception, but I guess the only way to use it is if I connect an amplified antenna to it's input since it has no RF amp?

Jonathan

Gorgeous, Pete!

Hey Pete,

Very nice set up on your CT-100. The color looks great and the convergence looks spot on. Congratulations.

-Steve D.

<<My gnawing itch wonders if WB11 actually transmitted the video with wide-enough gamut to make the effect I saw on the CT-100 vs. the HDTV. I wonder if the cartoon makers had their software set to 1953 NTSC. I wonder if the NTSC generator in my VCR is spitting out a color bar signal good enough to calibrate the CT-100. I wonder, as I wander…!>>

yup unless it is calibrated pretty good as far as color, you could always be seeing just more green due to off-value resistors, coil adjsutment issues, variations in drive of the guns etc. in the color section of the set. The potential for that old tube to display true NTSC is one thing... how accurately that old chassis is going to present it as it currently sits is another. All my old sets seem to have tendency to play up certain colors over others (mainly red) but not enough for me to go in and perfectly realign the color section, plus I don't really have the equipment necessary.

On the subject of pictures on working CT-100s... Steve D. demonstrated his CT-100 for me one day back in '84 or '85, and that was the first time I ever saw a CT-100 turned on. Well, the show that we happend to get was a live news feed from the McMassacre (in progress at that moment) in Chula Vista, CA. A rather macabre way to remember my first CT-100 viewing, but it is a sad and real part of history in California. We sat glued to the little vivid image, maybe for a moment overlooking the fact that it was a CT-100 at all. The CT-100 was, for an instant, restored to its original purpose as a medium of communication of sorts. I wonder if Steve remembers that day??? Deep thoughts :sigh:

Charles

...old sets seem to have tendency to play up certain colors over others....
What finally made me go public… ‘er, AudioKarma, was (1) achieving ‘standard’ HDTV-hues that are eyeball-duplicate on the CT-100 and (2) finally accepting the modified chroma-AFC alignment-procedure as okay (where final tweaking of L41 is needed because the circuit needs it, not because a component has drifted).

It should be remembered that all other hues on the CT-100 screen eyeball-matched those on the ‘standard’ HDTV screen. Only the green stood out and only on that character’s hat.

Here’s another CT-100 screen shot taken the same night. There are three different areas of green; two on the hat and one weird snow-capped mountain whose base is green seen through the now-open door. That green matches the HDTV green.

So, I’m speculating for now that the striking green on the character’s hat is a result of wider gamut and not some unusual peaking or weird spurious oscillation somewhere in the CTC2 chassis.

But I could be wrong. And so my next step is to rearrange my living room over the next couple of days, time permitting, with the CT-100 to the right of the HDTV. Then develop some photographic evidence supporting or debunking current speculation.

Was chatting with John Folsom yesterday and recalled that in September I reported the same effect as here. That time it was the eyes of a cartoon character that were vivid on the CT-100 but not in control images.

Here it is: “There's a commercial playing for a Lilo&StitchII (sp?) DVD. The bug-eyed character in the commercial on the CT-100 has bright, intense, large lime-green eyes that pop off the screen at you. Interestingly, in an A-B comparison between the CT-100 and my 38-in. widescreen CRT HD set, there's no similar effect on the HD set, although there may be setup issues to consider. Just came back from seeing the DVD at Target. The eyes in the print version were pale blue and didn't even appear to have been designed to draw attention --nothing like the TV ad to my eyes anyway.”

That's still a truly GORGEOUS picture any way you cut it-Man, I wish I'd scored a CT-100 back about 20, 25 yrs ago when they were just junky old TVs....-Sandy G.

I have been in the back bedroom doing final adjustments of my CTC-10 and was flipping around and noticed that South Park also (now it's on free tv), I think I'll watch it again and see what the dude's hat looks like! (ok it's not a 100 but oh well I'll take what I can get ; )
You should send these pics to the creators of SP and tell them this is what their cartoon ACTUALLY looks like : )
Frenchy

Most digital still cameras use the sRGB gamut (same as HDTV), and computer monitor primaries are similar, so showing what the sets actually look like to the eye will be a problem (although you should be able to see a difference of some kind in photos of the two screens).

Years back, a SMPTE monitor committee had two identical tubes made up (by Sylvania, IIRC) except for the green phosphor, one sulfide green and one NTSC green.. They were mounted in identical monitors and set up in the engineering lab studio at NBC in New York. They had some brightly colored objects in front of the camera including something "Kelly green". With this setup you could clearly see the difference, not only in the greens, but in the cyan saturation and the relative brightness of cyans and reds. They eventually demonstrated that you could get reasonable/acceptable (though not perfect) rendition of colors within the sulfide gamut by changing the matrix in the monitor. As a result, future monitors (Like the Tektronix Trinitron-based series) had a switch to turn the matrix adjustment on and off. You would set up the hue and chroma on color bars with the switch off, then turn it on to get reasonable flesh tones.

...you could get reasonable/acceptable (though not perfect) rendition of colors within the sulfide gamut by changing the matrix in the monitor. As a result, future monitors (Like the Tektronix Trinitron-based series) had a switch to turn the matrix adjustment on and off. You would set up the hue and chroma on color bars with the switch off, then turn it on to get reasonable flesh tones.
Wayne: Did the capability of the broadcast industry to transmit NTSC gamut shrink with the advent of SMPTE standards?

Or, is it possible — maybe even likely — that the difference in green between the HDTV and CT-100 I saw is a lucky confluence of NTSC-gamut-capable broadcasting plus an overly enthusiastic graphic artist? Rather than some Pete eye-brain quirk!


Also, I won’t be content making CT-100 matrix adjustments using a DVD and a VCR modulator. I suspect that my best chance at a calibrated NTSC-modulated color bar signal is an over-the-air signal.

At one time, broadcasters around here transmitted color bars after they signed off. Nobody seems to sign off anymore. But I found Ch. 13, the PBS station, did so at three a.m. last weekend and transmitted over-the-air color bars.

But I slept right through it. So this weekend if they repeat the bars I’ll try again and use the R and G and B filters that come with Video Essentials to check the two sets. Which brings up another point. I didn’t see any traceable calibration stickers on the color filters… :rolleyes:

Pete,
Try to give the engineering staff at the PBS station a call. I’m sure there’s a good chance once you tell them what you are doing and why they may help you in some way. At the very least they may tell you when they are going to have color bars up.

Great Picture

Good luck
Steve

Pete,

The question of what you should see on today's NTSC transmission is almost unanswerable. The taking characteristics (spectral response) of cameras is not an ideal match to the human eye to begin with (just too difficult to do). Major design criteria are a proper red/green crossover to get flesh hues right, plus a matrix to match the expected monitor primaries generally. Camera designers can do a mathematical calculation of the camera's performance based on a set of color chips, like the Macbeth ColorChecker chart, and adjust the camera matrix to match NTSC. But they would be foolish to not check it on a modern monitor. So, do current cameras and film scanners match NTSC best, or are they tweaked towards current monitors? I don't know, and I don't know that camera makers release this info - they sell cameras based on price, features, and how good they look in a display studio at the NAB convention. Beore blamng the camera guys for tweaking, consider that consumer receivers wiht non-NTSC phosphors have had a wide variety of matrix fiddles to make their rendition closer to NTSC (like the professional monitor matrix I wrote about). So, the system in the US has essentially been out of control.

Now, if you ask about PAL, the answer is simple: PAL standardized on the non-NTSC phosphors and specified their colors precisely, so they cannot transmit colors out to the NTSC gamut. HDTV is the same way - smaller gamut, but precisely defined.

Older material made with image orthicon cameras is intended for NTSC phosphors, but those cameras had no matrixing, so they are the best you can get with optical filtering only. Like most color film, they increased saturation by using narrower than theoretical R,G, and B filters, reducing the need for the matrix.

I was going to say that using the DVD and modulator should not be a problem, but it depends on the modulator having the proper R-Y and B-Y gains, and I suppose they might be wrong (although I think it's unlikely). A video tape of the color bars off your local station should work, since the tape shouldn't affect the R-Y and B-Y differently.

What local station is that? If you got through to the chief engineer and told him what you're doing, you likely could talk him into putting up the signals you want -especially if you invited him over to see the result.

The main requirement for the video essentials filters is that each one suppresses the other two primaries well enough that they don't affect your judgement - so traceable calibration is not needed, just a deep enough color. You should be able to tell if the red filter is letting any green and blue through by looking at the green and blue bars, and so on.

Thanks guys. You've given me plenty to consider.

On another note, recall the label on the CT-100 shows 475 watts at 115 Vac as the power used by a Merrill.

Just measured it. With a 115 Vac line, the unit draws 415 watts with a PF of .85, which measures/calculates out at 485 VA / 488 VA. So in conventional terms the draw is more like 415 watts.

At one time, broadcasters around here transmitted color bars after they signed off. Nobody seems to sign off anymore. But I found Ch. 13, the PBS station, did so at three a.m.
Checked o-t-a colorbars early this morning. Couldn't see a difference between over-the-air bars or the same station received via cable.

Checked also the HDTV versus the CT-100 after setting both using R, G, and B filters. The green test looks better on the CT-100 and was able to demonstrate it for the site; the other colors test pretty much alike between the two sets. Here's a link:
http://home.att.net/~pldexnis/input/troubleshooting/matrixalignmentresults.html

To my eyes the yellow on your hdtv looks more 'yellow' than on the ct-100, which looks lime-greenish. Anybody else? Funny that's like the same color area that South Park hat is in. But I'm not looking at them directly, I'm just looking at pics of them on my monitor so....

---

Was that HDTV receiving an ATSC signal, or an NTSC signal? If it was NTSC, a lot of the problems you see could be caused by the sets digital processing.Both NTSC. When receiving analog broadcasts, ATSC sets I'm familiar with (not many) don't seem to equal a modern analog set such as the CTC169 series. I'm guessing the HD set matrix is responding the way it was designed. Jeff Landaro designed the video amp in that set; maybe he's available for an inside expose :D

The lime-green on the CT-100 Frenchy mentioned had been a problem for me too, although since the matrix balance was improved for red, the yellow no longer seems 'off' when viewing the screen. Probably attributable to the strong/wide-gamut green of the 15G.

1) your mono picture of the big set shows less green on the yellow bar, so you would expect its yellow to be less green
2) The red looks darker and the blue looks brighter on the CT100 than on the large screen. The yellow looks greener and the magenta looks bluer. I would check the white point (blue and green drive settings) on the CT-100. If your white is lacking in red, that could be part of the difference. Ideally, you should have a gray background wall in the room lit by daylight or artificial daylight to compare to, or at least be able to look outside at daylight for comparison. Anyway, in turning idown the green and blue drives, it helps to go too far (slightly pink whites) if you can get there, then return to a neutral white, rocking the controls back and forth while you zero in on the neutral point.

If your white is lacking in red, that could be part of the difference. Ideally, you should have a gray background wall in the room lit by daylight or artificial daylight to compare to, or at least be able to look outside at daylight for comparison.It might take a few days, but I'll readjust the B and G drives as per your suggestion; saw a D6500 fluorescent work light at Sears; bought it and have it behind the HDTV a la Digital Video Essentials. BTW, when a 100-percent red screen is applied to the CT-100, it swamps something and shows a dark mustard-yellow, although the 75 percent red is red and at least 'looks' okay. It's all about red in a CT-100 I guess. Back in the '60 when I last fiddled with a Merrill, never had this much fun nor learned so much new stuff about it.

Fantastic reading.You've done a marvelous job in resurecting this set.

My comment that follows is mearly a suggestion.If you're unfamiliar with adjusting gray scale,I thought I might pass on some basics to help.

From some of the pictures you've attached do show that your gray scale is off on both ends.This may be just the pictures,but if what is shown is what you're seeing on the set when looking at the stairstep pattern,it looks to me as if both ends are off.That pattern should show shades of gray from black to white when properly calibrated.It looks bluish on one end and greenish on the other.If you're trying to approach the NTSC color temperature of D65 (6500K),what will help is a colorimeter.Doing it by eyeball is impossible.Prior to any adjustments to these areas,it's imperative that the Black and White (brightness and contrast) levels be adjusted properly.

There are two different adjustment points,the lower end using a 20IRE window pattern and the upper end using a 100IRE window pattern.Most sets have these controls,whether it be by analog pots pots or by service menu access in the newer digital sets.The lower end controls are called cut or bias or even screen by some manufacture while the upper end controls are called drive.If you have R G B for both end,great.Some sets only have two,just depends on the manufacture.

A bias light behind the tv or screen is not a reference for D65 adjustment puposes.It's there for overall viewing reference.

I've had the opportunity to calibrate a few CRT direct view sets and projectors over a span of about 6 years,using a Philips color analyzer and test pattern generator.Have also used patterns from A Video Standard and Video Essentials.The patterns from VE are very good.Getting the gray scale to track properly isn't always easy nor do sets hold them well.But,if this can be done,then the set's color will be as true as it can be,without being shaded.

Please do not take any of my comments or advice as criticism.On the contrary,I am just ecstatic to see life being brought back to these sets.I remember them fondly and have always been fascinated by television.I don't have the repair background that you obviously posses,but my curiosity as to why they all looked different pushed my desire to learn as much as a hobbiest/part time member of ISF could with respect to picture quality.

I agree with what you say about using instrumentation to set grey scale. Actually, I have never had the advantage of being a TV repair technician. For most of my work life I was an editor of one type or another. But I’ve also had opportunity to make a living troubleshooting to component level and have spent a few years working with instrumentation including initial power-on thru final calibration. All this is in support of my first sentence.

I’m going to check eBay; perhaps a reasonably priced colorimeter still in acceptable calibration will turn up.

Some things I’ve grown to acknowledge and appreciate recently are issues that effect stability of this restored Merrill. My feeling is that it’s a result of the original design rather than some artifact of age or the restoration process. In discussing this with John Folsom, who of course is a premier collector of 15-in. vintage color, it seems that most vintage sets are fickle, but the Westinghouse H840CK15 is far more stable than the CT-100, particularly in the area of high-voltage regulation, which I find, in the CT-100, is apparently an issue in an attempt to achieve brightness suitable for a desired, wide, grey scale.

Another area that’s been challenging when adjusting the matrix is to achieve a toned-down green component in the color bar display. It’s well known and fully appreciated that the red phosphor in a 15GP22 is by far the least efficient. I expect to work more on these challenges this weekend, but perhaps there’s just not enough latitude in the red to overcome the brightness and more importantly perhaps, the very wide green gamut, when adjusting grey scale (as you say, 20IRE to 100IRE) before trying to get eyeball-perfect color bars.

As I said, never had hands-on TV repair experience or did I ever work in broadcast video, so much of this detail stuff is new to me. Add to that the fact I’m an old guy….

Appreciate all the comments and suggestions received along the way. In particular, Old_TV_Nut with all his envious TV-engineering experience who kindly nudges me in the right direction now and then.

Have attached a shot taken this morning of simultaneous ATSC-NTSC broadcasts. The two ends of the engineering spectrum match fairly well in this shot, but I’ll admit to toning back the HD set in brightness and contrast a bit.

Pete,

A great picture! Keep at it.

Getting a precise gray scale setting is difficult without a color meter, but IF the bias and drive controls do not interact too badly you can usually get a pretty good result by eyeball. It really helps if the controls can be rocked back and forth through the correct point - you can go for decreasingly obvious misadjustment as you rock the control back and forth, and zero in on a good point. The ideal is to be able to set the lowlights and the highlights separately, doing the blacks/dark bars first - but not all sets will let you do this. Looking at the CT-100 schematic, if the DC clamping is working OK, you should be able to set the lowlights close and then set the drives for proper white. Then touch up the lowlights for precise tracking, and go back and forth from highlights to lowlights again if necessary.

Because of differences in phosphor spectra, a filter colorimeter may be slightly off in its readings. The Zenith optics lab had to use a master spectroradiometer to calibrate filter-type colorimeters to the current phosphor set - the colorimeters would then have a multi-positon switch for different calibrations. The spectroradiometer was calibrated against a NBS traceable standard lamp, and then the color was calculated from the measured spectrum using the CIE standard obsrerver curves. (These curves have been shown to have some errors, but that's another story). I believe that nowadays there are better ways to calibrate than a standard lamp, using power measurements of laser sources, but I haven't kept track of what optical instrument companies are actually doing.

The best white point setting (for one observer) can be made using a split-screen D65 lamp. This device has a window that is half open to the CRT and half mirrored to reflect the D65 lamp. The view is of the screen gray bar immediately adjacent to the lamp gray, with no intervening frame line. Any one person can get a near perfect match (for him/her self) of monitors having any phosphors by using this. However, other individuals likely will see the match as slightly off due to normal color vision variations. I and one of the older engineers always disagreed on how much blue drive produced a match. (He needed more blue.) Now that I am older and slowly developing cataracts, I probably need more blue than I used to.

The colorimeter substitutes its filtered spectral responses for the human eye, which is reasonable but not as accurate as a spectroradiometer, hence the need for multiple calibrations depending on the phosphor characteristics. I would guess that the colorimeter will be fairly correct for the different greens, both of which have smooth spectra, but may show errors due to the difference between the CT-100 red spectrum and the spikey rare-earth red spectrum of a modern tube.

So - if you get a colorimeter, and the two sets don't end up looking like the same gray scale, you may have to trust your eyes.

Just do that old psychology trick I read in one of my old tv repair books - hire somebody to set the greyscale for you and tell them to ask YOU when they have it white : )
They said repairman should do that to prevent the customer from a callback complaining "this thing is green", because they are the one that decided it was white to begin with, heh heh.

I have been experimenting with the relative setting of the G2 grids. The attached photo is with a low-brightness grey G2 setup (didn't upload for some reason; musta been too big. Substituted an ad c.u.). It is fairly decent and still viewable in the morning light. When a brighter grey is obtained with a relatively greater G2 setup, the resulting picture will lack adequate red phosphor output, an effect that is particularly noticeable where green is an element of the color being reproduced (as in that odd hue in the background of the GMA-set).

A low G2 grey setup provides greater G1 (control grid) response; a high G2 (brighter grey) setup delivers a brighter picture. With the greater G2 setup, I was able to watch the set during a bright sunny day with just the blinds closed.

So far, I haven’t been able to have it both ways. :thumbsdn:

Next step is to backup farther and readjust the red purity, which has deteriorated since set up weeks ago, as discovered last weekend during G2 adjustments. This will be at least part of the solution. :thmbsp:

Hey Pete,

I have been following your restoration efforts with great interest. Seems there's no end to the technicial issues in trying to achieve the perfect image on a CT-100. As you, and the rest of us CT-100 owners have learned, this set is very high maintenance, and a bit temperamental. And, while it's fun, for a while, to tweak this control and that, you may just want to walk away for a time. Sit back and watch the beautiful results you have achieved. Enjoy the fruits of your labor. I love the photo of your CT-100 sitting in the corner purring away and displaying it's magnificent living color picture.

-Steve D.

Does the CT-100 have any kind of set-up switch that sets the video bias to a fixed value while playing with G2's? If not, you may be walking yourself away from midrange on the G2's and black level (brightness + any other video black level settings if there are any). If you can check the G2's against a service-info value, and/or look at the red video drive with a scope to see if it's clipping, that might help.

The piece of schematic that comes to hand shows R,G,B, drive capacitively coupled to the G1's, each with its own diode DC restorer to set the black level (birghtness) - plus the blue and geen have individual background controls.

I think it goes like this: When you raise the G2 voltage, the tube is harder to cut off, but that means you need more negative swing on the grids, which would not cause the red amp to clip on highlights - maybe the opposite. So, I think it's possible that when you turn up the G2's, you are reaching the max current that the red gun will deliver on the red highlights - just a guess, but if it's true, there's nothing to do but run it at lower settings.

It's amazing how you can tweak the tint on a black and white picture and it apparently becomes slightly red-tinted... but keep watching it for a minute or two and it eventually just looks like black and white again. Then put it back the way it was before and suddenly it will look green/bluish! Try this one - stare at a test pattern for about 30 seconds, then put it on a program. Wow look at all the pretty colors! : )
All this is probably why I don't spend too much time trying to perfect all the color settings etc., as long as it looks pretty good and people faces are flesh colored, that's 95% of it.

Hey Pete,

Enjoy the fruits of your labor. I love the photo of your CT-100 sitting in the corner purring away and displaying it's magnificent living color picture.

-Steve D.Matter of fact, last Saturday the set and I had a marathon date lasting 5.5 hours in the morning through early afternoon, then another 3.5 hours of quality time that evening. Tomorrow however the back comes off and the top gets popped in prep for that red purity setup I've been threatening to redo. Before that I'll scope the red gun to check for possible distortion under varying G2 settings. It's all good fun with the only bad thing a hold on the next project, restoring the '56 Philco.

Enjoying retirement,
Pete :D

Pete is correct, retirement IS fun!

I just wanted to say:

A few years ago the conversations taking place here could have only happened by phone or maybe mail. (assuming that, without this site, folks like Pete & Old TV Nut would even have heard of each other) Half of the phone conversations would have been forgotten. Now, here they are, in writing so you can go back & reread. We can all benefit from the knowledge here, today & hopefully for all time.

Hear, hear.

Or should that be: read, read (pronounced red red).

The thing that stands out to me in this thread is what a perfectionist will to to make a TV set be as accurate as possible ...just a pity that most programs today are pretty sloppy in terms of color and covered in dreadful station logos.

But then when you watach a film where the colour is part of the whole desing of the movie you realise why getting the best you can out of a TV is worth it.

But then being colour blind means for me getting the colours accurate is rather a subjective thing!

and of course ....here in PAL land the colour looks different anyway .... it is interesting how when changing from a PAL source to an NTSC one requires changes to the settings on the set... mainly because the black level is different.

On my Sony the "preset" color, brightness and black level auto-settings are clearly designed for NTSC sources as they are way off for a PAL source ...too dark and contrasty a dn way too much chroma but for NTSC are pretty good.

About a week ago I set off to investigate characteristics of the red gun signal. Data from the task has been added to a new Troubleshooting section on the CT-100 site. There are four entries so far; check the one from 11-19-05.
http://home.att.net/~pldexnis/input/troubleshooting/troubleshooting.html

Three weeks ago I readjusted the CT-100 and achieved a better hue match between the 'reference' digital set and the Merrill. It ameliorated my earlier supposition that intense green was a result of wide green gamut. Here's a link to the update page where the 12-9-2005 update appears:

http://home.att.net/~pldexnis/ct-100_restoration_log8.html

Very interesting, Pete! How does the comparison look on a gray scale now?

It seems the gray scale is a bit contaminated because the color control will not kill it completely, and so I don't have a recent shot. I will have to confirm this w/a scope, however, and try for one Monday morning. Last weekend, channel 13 ran pledge programming during their usual color bars. Hopefully they'll have raised enough $ to go back to color bars this weekend.

I have been experimenting with the relative setting of the G2 grids. The attached photo is with a low-brightness grey G2 setup (didn't upload for some reason; musta been too big. Substituted an ad c.u.). It is fairly decent and still viewable in the morning light. When a brighter grey is obtained with a relatively greater G2 setup, the resulting picture will lack adequate red phosphor output, an effect that is particularly noticeable where green is an element of the color being reproduced (as in that odd hue in the background of the GMA-set).

A low G2 grey setup provides greater G1 (control grid) response; a high G2 (brighter grey) setup delivers a brighter picture. With the greater G2 setup, I was able to watch the set during a bright sunny day with just the blinds closed.

So far, I haven’t been able to have it both ways. :thumbsdn:

Next step is to backup farther and readjust the red purity, which has deteriorated since set up weeks ago, as discovered last weekend during G2 adjustments. This will be at least part of the solution. :thmbsp:


Now it would be real neat to design a circuit that would adjust black level and white balance for a 15GP22 in a similar fashion found in today's modern TV sets. During the blacker than black and peak white pulses within the blanking periods the gun current for red, blue, and green would be individually compared to a reference and then G1 and G2 adjustments made automatically!

Now it would be real neat to design a circuit that would adjust black level and white balance for a 15GP22 in a similar fashion found in today's modern TV sets. It would make an interesting project.

At this point, if you adjust the G2 for a lower gray and view the set in subdued light the CT-100 picture compares favorably with a digital set tuned to the same analog broadcast. There are differences of course: at those times when the digital set shows virtually no phosphor glow, the same area on the CT-100 screen will sometimes show a very dim glow.

On a similar note, I’m borrowing a virtual multimeter. Hope to be able to develop a data-logger-type monitor that will keep a txt file record of circuit voltage. I’d kinda like to learn something about how critical the 115-Vac line-voltage spec is to optimum CT-100 operation. If it works I’d particularly like to gather data on how the high voltage varies with line voltage.

The last of my three vertical convergence transformers failed. One is used in a CTC2, the CT-100 chassis. Sunday morning June 18, 2006, the fuse protecting the H-V cage blew on turn-on. Unlike my two other failed transformers, however, which still display correct dc resistance, this failure wiped out the secondary. The tap is completely open. There are about 12 Meg between the top and bottom of the secondary where about 12 k-ohms should be. This part has an extremely high failure rate. Probably second only to the 'white' peaking coils that rot open.

For the repair, I tacked in one of John Folsom’s newly manufactured replacements I've had for about a year now. It was static-tested at about 4 kV across primary-to-secondary for a few hours when it arrived last June, and so I expected a no-issue installation.

On the bench, the H-V ran a steady 21 kV with the new transformer in place and the H-V control set wide open with a 115-Vac line. The focus voltage, which passes through the secondary and is the reason for all the stress on the transformer, is steady at 3.5 to 4 kV, depending on the focus control position.

Picture is of the new transformer on the rear of the H-V cage.

In the future, I’ll remove the failed core from the transformer housing and use the original case around the new transformer.

Returned the chassis to the cabinet today, cranked the H-V control back to the specified 19.5 kV and while I haven’t reconverged it yet, it's perfectly watchable.

Nice clean new-looking seleniums there, and may I add a nice clean chassis overall! Are those seleniums new? I've never had to change any on a CTC-2. On the subject of reproduced CT-100 stuff, has anyone made focus and convergence pots? I've had a couple of them with open convergence pots, and one with an arcing focus pot.

Charles

Nice clean new-looking seleniums there, and may I add a nice clean chassis overall! Are those seleniums new? I've never had to change any on a CTC-2. On the subject of reproduced CT-100 stuff, has anyone made focus and convergence pots?
Those selenium diodes are there for looks only; while I have not had a pair fail either, for safety they were replaced electrically with a couple of 1N4005’s.

As you know, the failure of a vertical convergence transformer is particularly insidious because a common failure mode causes a chain reaction that burns out the focus pot. Too much focus current is drawn if the secondary shorts to ground; the 1X2B focus rectifier plate goes cherry, and the pot can literally blister on the outside and melt internally.

While its design voltage rating is unknown to me, the focus pot is the center of a three-element voltage divider with nearly 4 kV at the wiper. While I haven’t had to do it yet, I’ve seen an ordinary linear taper pot successfully substituted for the original one. Personally, if I have to do that someday, I’ll make sure there’s an insulated knob on the shaft before I adjust it. :yes:

I had a pleasant surprise when the chassis came out of the cabinet. Notice in the picture the hue control -- the variable cap on the end of the center shaft of the three running back from the front panel. It's in the dead-center position. Exactly where it was after aligning the chrome AFC a year ago.

Finally got to perform a full convergence on the set two days ago, and the newly manufactured vertical convergence transformer is doing a fine job. The procedure improved convergence to the point where the overall 15GP22 image -- to use the vernacular of the streets -- looks sharp as a gnat's ass. :D

A minor inconvenience is the weather. Yesterday is the second time in recent history that a spell of humid weather affected the high voltage. Not certain where the damn humidity planted the unwanted load, but it's highly unlikely that the new transformer is a factor. The last time this happened was a week after replacing the transformer. A three-week hiatus with no power applied to the set brought it back: the high voltage recovered after the weather turned dry.

What with the remnants of the hurricane passing through here recently, there's been so much rain the grass is so green it looks fake. So what better time to again check H-V under extended high-humidity conditions.

Last night I did it a little differently. With a 115-Vac line I pulled open the H-V lead then applied power. The H-V swung right up to 21 kV (about right for a CT-100 unloaded H-V supply) and stayed there.

Plugged the CRT back in and powered up again. Sure enough, after some mild frying the H-V settled at a slightly low 17.5 kV, but in a few minutes was back up to 19.5 kV.

I believe in my case the culprit is leakage from the flange; last year after restoration I had to remove and cleane the CRT and rubber insulator around the flange to arrest the same frying/leakage.

If you have to you have to. But not looking forward to pulling the CRT for another cleaning. Not so much for the work involved, but I don't like potentially messing up a satisfactory alignment. :thumbsdn:

What with the remnants of the hurricane passing through here recently, there's been so much rain the grass is so green it looks fake. So what better time to again check H-V under extended high-humidity conditions.

Last night I did it a little differently. With a 115-Vac line I pulled open the H-V lead then applied power. The H-V swung right up to 21 kV (about right for a CT-100 unloaded H-V supply) and stayed there.

Plugged the CRT back in and powered up again. Sure enough, after some mild frying the H-V settled at a slightly low 17.5 kV, but in a few minutes was back up to 19.5 kV.

I believe in my case the culprit is leakage from the flange; last year after restoration I had to remove and cleane the CRT and rubber insulator around the flange to arrest the same frying/leakage.

If you have to you have to. But not looking forward to pulling the CRT for another cleaning. Not so much for the work involved, but I don't like potentially messing up a satisfactory alignment. :thumbsdn:

I have run into humidity problems BIGTIME while working on TVs along the coast here in CA. That ocean humidity not only is wet, it's corrosive. It leaves a sticky white film on everything. The best solution, which I have done many times for customers, is to put a computer fan blowing across a small light bulb inside the cabinet 24 hrs/day. It works! The Mitsubishi big screens get very unhappy in the ocean breeze, and the arcing almost always gouges a channel in the glass from the anode holes to the nearest ground, ruining the CRTs :thumbsdn:

In the case of a CT-100, you could turn the bulb & fan on the day before you plan to run the set.

Charles

I have run into humidity problems BIGTIME while working on TVs along the coast here in CA. That ocean humidity not only is wet, it's corrosive. It leaves a sticky white film on everything. The best solution, which I have done many times for customers, is to put a computer fan blowing across a small light bulb inside the cabinet 24 hrs/day. It works! The Mitsubishi big screens get very unhappy in the ocean breeze, and the arcing almost always gouges a channel in the glass from the anode holes to the nearest ground, ruining the CRTs

How close o the ocean are you? Or to rephrase the question, how far from the ocean do you have to be in Southern California before this isn't a problem?

David

The light bulb/Fan trick basically raises the temp high enough to reduce condensate from forming on surfaces inside the TV. Another approach would be to place a tray of silica gel or drierite (CaSO4) inside the set for a day or so.

I'm 5 miles for the Ocean in San Diego. Even at this distance I'm careful about exposed high voltage anodes outside when the humidity > 60%. Of course, warm humid days and cool nights often leaves the air saturated causing dew to form on cooler surfaces - hence the possibility of arcing.

For three days now the set has been working w/o H-V problems, but if/when it happens to lose adequate H-V due to weather/humidity again, I'll remount the CRT without the mu metal shield and H-V insulating wrap. Should help pinpoint just where the short is taking place.

Two or three times a year I get to climb up on the roof after a major storm and reorient my $10 antenna towards NYC again, like yesterday. See photo.

My humidity problem comes from the lake across the street, which runs three blocks down to the Atlantic ocean, which is of course the real culprit.

Hey Pete,

Certainly looks like state of the art equipment. I hope you're not using a $10.00 ladder to get up there. My brother swore he would kill me the next time I climbed on the roof to fool with an antenna. So either way there is risk involved.
Be careful.

-Steve D.

Hey Pete,

...either way there is risk involved. Be careful.

-Steve D.You're right Steve, we seasoned guys have to step smart.

As Pierre Salinger quipped years ago, when quizzed by a reporter who asked if he were safe skating on a frozen pond:" I may be plucky, but I'm not stupid."

Actually, I had to crop the bejesus out of that cell picture to get it to load up into AudioKarma's guts (my access to Photoshop is temporarily down).

The full frame shows a flat roof. Plus there's an easy-access hatch from the third floor ceiling, with a built-in wall ladder. My son was up there too to keep an eye on the old man. :yes:

[Fodder for conspiracy theory threads. Much later, Salinger, press secretary to presidents Kennedy and Johnson, got into hot water in '96 for publicly arguing that it was not a 'spark' in a fuel tank that brought down TWA flight 800... ]