General Question

SirBailey's avatar

Whatever happened to the "Horizontal Hold" knob on televisions?

Asked by SirBailey (3130points) May 27th, 2009

I remember when every television had a “Horizontal Hold” knob. Some even had a “Vertical Hold”. How did the technology change so that televisions no longer have them?

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14 Answers

Bagardbilla's avatar

I believe it’s been moved over to the Sex channels ;)
No you have it right, it’s a feature of a by-gone era.
They all hang out with UHF, the clicking channel knobs, rabbit ears, and soon to be joined by the retired Analog Signal.

Bluefreedom's avatar

Digital television signals negate the need for a horizontal hold control. Plasma screen and LCD televisions do pretty well with no horizontal hold problems that I’ve ever seen.

IchtheosaurusRex's avatar

Early TV sets did not incorporate phase-locked loops to control the vertical and horizontal sync. All of the various components of the NTSC television signal had separate stages of amplification, and each amplifier had to be tuned manually. Many of the controls were on the back of the set, but some, like the vertical and horizontal hold, had to be tweaked so frequently that the control knobs were on the front of the set.

Integrated analog PLLs were developed in the 1970s. They were first used in TV sets around 1975, and virtually eliminated the need for manual sync controls. In more recent years, digital servos, which are even more stable than analog PLLs have been incorporated into TV sets. As Bluefreedom points out, on digital TV sets, there is no need for servo loops at all, as all of the signal information is in a digital form.

jrpowell's avatar

@Bluefreedom :: My Analog TV didn’t have a problem or a knob either. But I remember when our sets did.

jrpowell's avatar

@IchtheosaurusRex :: thanks for the info.. I learned something new today. Now I can go back to sleep.

Bluefreedom's avatar

@johnpowell. I can remember them too back in the stone age. Remember when VCR’s had tracking buttons also? They still might but I don’t know. I only have DVD players.

jrpowell's avatar

Remember when VCR’s had all the crazy pots to tune in channels? Recording TV was a pain in the ass.

IchtheosaurusRex's avatar

@Bluefreedom , the first TV set we had in our house was hand-built by my uncle, who was a radioman on a WWII destroyer and made a pretty good living after the war by being the only TV/Radio/Appliance repairman in the small Indiana town he lived in. The set had a 9” CRT and around 30 vacuum tubes.

Bluefreedom's avatar

@IchtheosaurusRex. I’d guess that was a very impressive feat back in those days (hand building a television). It must have looked a little strange, though, with vacuum tubes right?

IchtheosaurusRex's avatar

@Bluefreedom , you have no idea. You can see sets like this at the Henry Ford Museum near Detroit. In the early days of TV, they could not manufacture rectangular CRTs, so the screens looked like they do here. The one Uncle John built had a smaller screen than the DuMont shown in the picture, and the cabinet was made out of CDX plywood with a coat of dark stain. We eventually replaced it with a 14” Philco, but it was still full of tubes. You didn’t see transistors used in TV sets until the mid-1960s.

I’m not only old enough to remember these sets, I’m old enough to have worked on them. The first color TV I owned, I bought in 1975 from a guy who was basically throwing it out. It was around 10 years old when I got it. The tuner was transistorized, but most of the chassis was vacuum tubes. It needed a focus coil, which I replaced, and some new potentiometers. I used it for around 4 years, and it still worked when I gave it away. If you didn’t want to watch TV on it, it made a pretty good space heater.

jrpowell's avatar

@IchtheosaurusRex :: How long did those take to display an image?

basp's avatar

Ain’t technology wonderful!?

I can remember before most households had televisions. What a grand day it was when our family finally got one! And, they broadcast only for about six to eight hours a day on about three channels. Can still remember staring at the test pattern waiting for something (anything!) to be broadcast.
We certainly have come a long way!

IchtheosaurusRex's avatar

@johnpowell , it would take around half a minute for the tubes to heat up, maybe a couple of minutes for the amplifiers to stabilize. The picture would be fuzzy at first. It was interesting to turn one of those old sets off, too. There would be a bright spot in the center of the screen because of residual magnetism in the picture tube and the cathode still being hot.

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