Those of us who worked in TV repair shops, back when there was such a thing, will likely remember the cardinal rule of TV repair: Never touch the yoke if you can help it. The complex arrangement of copper wire coils and ferrite beads wrapped around a plastic cone attached to the neck of the CRT was critical to picture quality, and it took very little effort to completely screw things up. Fixing it would be a time-consuming and frustrating battle with the cams, screws, and spacers that kept the coils in the right orientation, both between themselves and relative to the picture tube. It was best to leave it the way the factory set it and to look elsewhere for solutions to picture problems.
But how exactly did the factory set up a deflection yoke? We had no idea at the time, only learning just recently about the wonders of automated deflection yoke yamming. The video below was made by Thomson Consumer Electronics, once a major supplier of CRTs to the television and computer monitor industry, and appears directed to its customers as a way of showing off their automated processes. They never really define yamming, but from the context of the video, it seems to be an industry term for the initial alignment of a deflection yoke during manufacturing. The manual process would require a skilled technician to manipulate the yoke while watching a series of test patterns on the CRT, slowly tweaking the coils to bring everything into perfect alignment.
Automating this process would have been a huge competitive advantage for a company like Thomson. Being able to provide correctly aligned CRT assemblies to a manufacturer would have been a productivity booster, especially since Thomson claimed to be able to adjust the process to the customer’s assembly line needs. They also say that the automated yamming process took just 30 seconds per tube thanks to a series of sensors and cameras watching the screen. The human element wasn’t completely eliminated, though; at the 3:50 mark, some unlucky QA tech is shown watching an endless carousel of tubes flashing a few test patterns to confirm the process. And you think your job sucks.
It’s not exactly clear when this video was made. The title suggests it was 1995, and that seems about right from the technology in the video, which includes a computer running a version of Windows from around that timeframe. Ironically, the LCD monitor on that touchscreen display was a harbinger of things to come for Thomson, which was out of the CRT business in the US less than a decade later.
The giant calendar on the wall over the shoulder of Bill Miller is December 1994 January,Febuary 1995. Confirmed by the perpetual calendar in my pocket ref book (calendar 1&2)
Indeed, February 1st, 1995 was a Wednesday.
Maybe they could align the audio instead?
Fun fact: if you’re watching the Simpsons on NTSC, you can change the “tint” control so the characters have realistic flesh tones, and then the rest of the cartoon comes out in the colours originally conceived by the cartoonists.
And if you watch the Simpsons on SECAM then only Lisa sounds right.
Citation needed.
Hey real quick would you wanna buy a bridge from me? It’s in Brooklyn
I’ve always found that repetitive jobs requiring full concentration are relaxing. Focus on the one task and turn off the rest of my mind. Leave work refreshed and ready to take up interesting activities.
With the price of eggs today, no one can afford to yam anymore. I’m just yoking!
That tends to happen when you slaughter a tenth of a billion chickens for no good reason right before inauguration day!
KFC would disagree about the ‘no good reason’ part.
Yeah yeah you’ve already run that scam, people aren’t falling for it anymore
Test for flaws directly on the assembly line
“The spell check keeps saying do you mean ‘lcd’ whenever I type CRT. It probably doesn’t mean anything”
Wild guess: Yoke Adjusting Machine?
Yoke Alignment Method,
Or….
Yoke Automation Miracle?
Yoke Alignment Magic
Yoke Alignment Manipulation
Yoke Adjustment Machine https://patents.google.com/patent/WO2007027195A1/en
Color televisions included a convergence panel for adjusting the three electron beams (RGB) so that they coincided across the entire screen. Many sets allowed the service technician to detach the convergence panel so that adjustments could be made from the front of the set. Using a signal generator that produced a grid pattern, the technician would go through a lengthy convergence procedure. It required skill developed through months/years of practice. The article is quite right, you didn’t mess with the yoke, the convergence magnets, or the other adjustment magnets on the neck of the CRT unless you absolutely had to. Installing a replacement CRT is a good example of where it was unavoidable.
Later semi-digital TVs and displays also had corrector circuits, even non-volatile memory to remember settings which allowed to adjust some of yoke effects on image shape – because over time ferrite and coils could change/degrade or be replaced with the CRT.
But it wasn’t unsoluable. They were striving to standardization. Heck, we replaced a CRT in a late Soviet color TV Record (ВЦ-311? I may misremember model) with compatible Trinitron one (TV was based on Trinitron design) and it required minimal adjusting.
It was ВЦ-381. 311 was older , had custom CRT connector and had oddly exposed controls in front. 381 had a false grate in front protecting adjusting controls.
0:28 IBM 8515 monitor sitting on top of no idea what “Intel inside” non IBM system
5:20 that 3D CAD system looks expensive. Anybody recognize it?
5:40 “YAM 2G” System itself seems to be running on Windows 3x
6:23 pre 1989 DELL (older logo) monitor/keyboard
“Ironically, the LCD monitor on that touchscreen display”? I don’t see any LCD monitor. I see a orange gas-plasma display like we know it from the IBM P60 and Toshiba T5100. The full color touchscreen we see is a CRT with a very early infrared touch overlay I believe.
I have a box of the smallest CRT tubes, 1″ black and white displays.
Sadly I have no yokes for them.
Well, I have ONE.
But I had an idea.
What if I made a deflection yoke.
Not a correct one, just one that allows me to control the beam, even if you can’t send a TV signal.
Then, use a computer to deform the picture in the opposite way to how the yoke does.
Sort of a digital yoke.
Transit a grid.
Measure the grid.
Write software to deform the TV signal to correct the grid.
Then run tv through that transformation routine.
A sort of hybrid digital yoke.
Would that work I wonder.
As an ex-TV repair tech in the last days of CRT sets, I have done many tube swaps and the description of the involvement is way overblown. You just slide the yoke on and rotate it until everything it level, tighten it. Fiddle the centring rings if needed, then the purity rings to tune the colour quality.
Then the actual annoying part for colour CRTs were getting out any residual purity blotches (colour shifted areas) with small magnets stuck to the bell of the tube as needed
Same for projection sets. Yoke rotation and ring adjustments are trivial.
Most of them have a built in grid generator for convergence; older sets had a tray of pots – an array of various wid/hei/key/bow/etc for each colour.
The newer sets were all digital with the same broad settings but an additional Point-Point ability to shift tiny areas of the screen/per colour again. This was tedious, and if you shifted something too far you would get a nasty S-curve in the grid that was not intuitive to remove
When I was a teenager I built Heathkit color TV. This was a rather sophisticated full featured 19″ color TV with remote, stereo sound, and on screen menus. Very advanced for 1986 or so. Anyway, I did have to these adjustments. Part if the kit was building a board to generate the necessary test pattern. It wasn’t that difficult and it was a fun part of the experience. Note also just the thrill of sticking your hand repeatedly inside a working TV.
You could have been nice and asked the producer for permission to use, and he might have been able to answer some of these questions.
Thomson, a terrible joke in the TV industry played on us by the French😟. The stuff that was foisted on us in the UK was awful. ICC9 and onwards anyone? The stuff of nightmares.