Westinghouse H-223 restoration

[old_tv_nut]

"BTW those two 12K resistors in parallel is how it was originally built and shown on the schematic. Two 12K, 1W in parallel
I'm thinking 5.6K or 6.8K wasn't close enough?"

Can you post the circuit? If the original resistors were 10% or 20% tolerance, there wouldn't be much advantage in using two for a nominal intermediate value. More likely they had 1 watt components available cheaper than small quantities of 2 watt - but that could depend on the particular circuit.

[bandersen]

https://www.earlytelevision.org/pdf/...23_rider_3.pdf

[old_tv_nut]

Series dropping resistor for screen grids and DC restorer B plus - no reason for precision that I can see. I note there is only one 2 watt resistor in the bill of materials - cathode bias for the horizontal output. There are a few higher wattage wire-wounds, but all the other composition resistors are 1/2 watt or 1 watt.

The peculiar thing is that there is only 1/6 watt dissipated in each of those two 1-watt resistors (see Fig. 41). Maybe this was to keep a low temperature rise and prevent the value from drifting - I'm thinking the actual DC restorer B plus is not critical because brightness control setting takes care of it; unless it drifts, requiring readjustment of brightness. You could test this theory by connecting/disconnecting a 100k or so resistor across these two and see if the black level changes.
See Fig. 30, where it appears to be so.

[old_tv_nut]

Another thought - I wonder how well the DC restoration tracks with line voltage changes.

[vortalexfan]

Another Interesting fun fact, Philo Farnsworth (the man behind the Capehart and Farnsworth Radio and TV Company) actually was a pioneer in early TV manufacturing and had many patents in TV development which RCA ripped off from him, and when Philo tried to sue RCA for patent infringment they took him for a ride and drove him into bankruptcy.

So the majority of those Patent Nos. refrenced to on the back of these TVs that are claimed by RCA are actually Farnsworth Patents NOT RCA Patents.

[Pio1980]

Originally Posted by vortalexfan

Another Interesting fun fact, Philo Farnsworth (the man behind the Capehart and Farnsworth Radio and TV Company) actually was a pioneer in early TV manufacturing and had many patents in TV development which RCA ripped off from him, and when Philo tried to sue RCA for patent infringment they took him for a ride and drove him into bankruptcy.

So the majority of those Patent Nos. refrenced to on the back of these TVs that are claimed by RCA are actually Farnsworth Patents NOT RCA Patents.

"We don't pay royalties, we collect them".
Popularly attributed to David Sarnoff/RCA.

[Electronic M]

Originally Posted by vortalexfan

Another Interesting fun fact, Philo Farnsworth (the man behind the Capehart and Farnsworth Radio and TV Company) actually was a pioneer in early TV manufacturing and had many patents in TV development which RCA ripped off from him, and when Philo tried to sue RCA for patent infringment they took him for a ride and drove him into bankruptcy.

So the majority of those Patent Nos. refrenced to on the back of these TVs that are claimed by RCA are actually Farnsworth Patents NOT RCA Patents.

Farnsworth was only behind the Farnsworth Company.

Capehart was a separate company known for luxury phonograph and Jukebox equipment. Their turnover changer that started as a a jukebox mechanism became the standard for premium home audio both in the high end consoles Capehart sold (which with add on remotes and amps became whole home radio and music systems) and paired with other high-end radios like E. H. Scott.

The 2 companies later merged since Capehart wanted into emerging Television Tech and Farnsworth needed the backing of a financially solid company to deal with RCAs nonsense.

[bandersen]

You guys have the timeline and facts a bit off. Philo goes back much further. He filed his patents in the 20s and had his battle with RCA in the 30s. He won in 1938 with RCA agreeing to pay royalties.

Then the war broke out and production was halted. Unfortunately for Philco, by the time the war was over and TV resumed, his patent had expired.

Farnsworth Television and Radio Corp was based in Fort Wayne and operated from 1938 to 1951. It was bought out by ITT in '51.

Farnsworth bought Capehart in 1938 using the money he won from RCA.

[nasadowsk]

Legend has it the RCA lawyer was crying when he was signing the settlement papers. Probably because he knew Sarnoff was pissed.

How many times did someone take on RCA and win?

[vortalexfan]

Originally Posted by bandersen

You guys have the timeline and facts a bit off. Philo goes back much further. He filed his patents in the 20s and had his battle with RCA in the 30s. He won in 1938 with RCA agreeing to pay royalties.

Then the war broke out and production was halted. Unfortunately for Philco, by the time the war was over and TV resumed, his patent had expired.

Farnsworth Television and Radio Corp was based in Fort Wayne and operated from 1938 to 1951. It was bought out by ITT in '51.

Farnsworth bought Capehart in 1938 using the money he won from RCA.

Yes, but that doesn't change the fact that Farnsworth was the one who originally designed the technology that made TV as we know it now possible and that RCA did indeed try to take Farnsworth for a ride when it comes to trying to get his patents which he did as you said eventually win out in court over RCA but then by the time it was all said and done his patents ran out which basically meant that RCA could then take those patents and claim them for themselves (even though they really werent theirs to begin with)
hence why RCA was considered a dirty operator for many years was because they basically held a monopoly over the patents for many various electronics technologies including ones that weren't originally theirs to begin with, which is why if you look up some of the patent numbers on the back of many old RCA and RCA Clone/licensed TVs you'll see that they are actually patents originally assigned to Philo Farnsworth and then in small print under the original patent assignee is the words "reassigned to RCA".

[dtvmcdonald]

Originally Posted by vortalexfan

Yes, but that doesn't change the fact that Farnsworth was the one who originally designed the technology that made TV as we know it now possible .

Not really. That was Vladimir Zworkin. There really was one absolutely key invention, which was the iconoscope camera. This was the first device that stored up information from photons no matter when they arrived, at every spot
on the picture. Even today they make really good pictures in bright sunlight, for example, in a camera made by a guy in Japan using a solid state preamp.

In broad daylight even my WWII bomber camera make quite OK pictures.

[old_tv_nut]

Originally Posted by dtvmcdonald

Not really. That was Vladimir Zworkin. There really was one absolutely key invention, which was the iconoscope camera. This was the first device that stored up information from photons no matter when they arrived, at every spot on the picture. Even today they make really good pictures in bright sunlight, for example, in a camera made by a guy in Japan using a solid state preamp.

In broad daylight even my WWII bomber camera make quite OK pictures.

This is a somewhat condensed version of the technical issues of sensitivity. The iconoscope was only 5 or 10 percent as sensitive as a tube should be that stored charge for a full field. This was because of the large secondary emission of charge due to the high-velocity scanning beam. The sensitivity could be increased about 10 times by adding an electron image section in front of the scanned plate. This was done successfully in the "Super Emitron" (image iconoscope) used in Europe. RCA was well aware if this, but didn't use it due to interference of Farnsworth's patents for an image section. It is a blatant example of how RCA's business policies sometimes held back technology instead of advancing it. RCA eventually did use an image section and combined it with low-velocity scanning in the even more sensitive image orthicon, which achieved 100% storage efficiency.

[dtvmcdonald]

old_tv_nut: well, yes, what you say is important for the history.

But the important thing is being first to get a great idea, get it to work even
a little, and then get it to market.

For example, the Plumbicon works great, but it was an incremental idea.
And it was the trailing edge.

Comb filters were great, but trailing edge.

Digital was a great idea for great pictures. But its big deal is allowing
stuffing 8 channels of utter crap into the space on one, not quality for that one.

[bandersen]

I finished recapping the power supply.
That took care of the bends.


I think all that's left is tweaking the sound and picture centering/linearity.

[bandersen]

The contrast control in this set is really odd. They feed the output of the detector from the back of the set to the front through coax, use a potentiometer to vary the level, and run another coax line back to the video amp.

That's what the tube is running down the middle.




Wouldn't it be much easier to just vary the bias/gain on the amp?