That's a cool book. Its amazing how much complexity and ingenuity went into those projection systems to create larger viewing screens only to.have the devices become obsolete so quickly afterwards when larger crts became commonplace. Can't wait to see one of yours working
Thank you for this awesome video!...the TV Picture Projection and Enlargement book was fascinating and, as always, your insightful comments brought it to life!!...good luck on your post-war projection television restorations!!!
I remember seeing a news item in one of the electronics magazines, published in the late 60s I think, that tolded of a laboratory development of a projection TV system that used three different colored gas lasers to project an image onto a screen.
I'm sure many watching your channel remember the rear projection sets of the 90s. STK Audio chips for deflection, Sony fungus growing in the projection tube antifreeze. I had a TV repair friend that used motorized hand truck and motorcycle ramps to move the beasts. A HDTV rear model he installed weighed 500lbs.
I can't wait to see you work on the Scott projection TV :) For years now I've been anticipating you to get to work on it, because to me this is such a radically different and interesting setup.. I can't imagine anyone better qualified than you to get to work on it, Bob. So do get to work on it whenever you can, I for one can guarantee you I'll be watching every episode LOL
I assume these early projection CRTs were pretty ferocious x-ray emitters with 30kV acceleration and focused on such a small spot, and the mentioned 80-100kV ones are well into x-ray machine territory. I wonder what kind of dose you'd get standing in front of that "searchlight" looking unit. Cool little book, the history of display tech has so many oddball solutions that were viable for less than a decade and mostly in fairly high end niches and are now almost completely forgotten.
No. They don't emit any X-rays. Not the CRT any way. You need to hit a metal target to gen x-rays. The HV rectifiers might but they are sealed in a metal box.
@@bandersentv Interesting. I can't say I've ever experimentally confirmed it but i have read that x-rays can be a hazard with electrons hitting glass windows with sufficient energy, but it's completely possible it was overly cautious advice to high vacuum/high voltage experimenters and/or it depends on the specific glass composition.
I forgot that these are aluminized so there is a thin metal surface behind the phosphor. No warning in the CRT data sheets though. Other HV tubes like 1B3 or 6BK4 do have x-ray warnings printed right on them though. I've seen some other youtubers try to detect x-rays coming from TV CRTs with a geiger counter and got nothing. Now it could be that those detectors are not sensitive enough or any x-rays too weak.
I like to magnify 7 inch tv by watching your 7 inch repair vids on my Samsung 4k bigscreen. You zoom in and the picture is 3 feet across! I never see the scan lines. Resolution is great even at 3 feet Ha- Ha ! I have read that the mirrors on projection sets are front silvered and if you use a normal rear silvered bathroom mirror the set will not focus. I also read the mirrors in DLP projection tvs found on the side of the road are front silvered and may be a cheap resource. I had a Samsung DLP and they had a great picture until 4 K came out. Interesting vid as always. I think I bid over $200 for a Zenith flashmatic flashlight this year on ebay and lost.
The thing about normal rear silvered mirrors is that there is a reflection from the surface of the glass in front, that double reflection messes up the optical design. A shaving mirror is no where close to the curvature accuracy needed for this sort of optics. The front surface mirrors are very easily damaged, even just exposure to the air will have an effect in time. First surface mirrors are used in the large telescopes and need to be re-silvered every five years or so.
Minor nitpick here, but the electronics brand is spelled "Philips" (with one L). Phillips (with double L) is the brand that makes cross-head screws. Philips used the "Norelco" brand in the USA to avoid mixing the two companies up and to prevent a trademark lawsuit.
Phil Nelson has an article on his working Emerson 609 projection set using the protelgram unit. I'm currently working on restoring my Emerson 609 but sadly I will have to find a new 3NP4 as mine has a line burnt straight across the face of the tube.
That's a cool book. Its amazing how much complexity and ingenuity went into those projection systems to create larger viewing screens only to.have the devices become obsolete so quickly afterwards when larger crts became commonplace. Can't wait to see one of yours working
Thank you for this awesome video!...the TV Picture Projection and Enlargement book was fascinating and, as always, your insightful comments brought it to life!!...good luck on your post-war projection television restorations!!!
Thanks for posting this along with the photos from the Early Television Museum. The web link (QR code) linked to all kinds of good into.
I am really looking forward to seeing a Projection TV restoration and demonstration.
I remember seeing a news item in one of the electronics magazines, published in the late 60s I think, that tolded of a laboratory development of a projection TV system that used three different colored gas lasers to project an image onto a screen.
Bob love this update been waiting for follows very happy glad to see progress being made.
I'm sure many watching your channel remember the rear projection sets of the 90s. STK Audio chips for deflection, Sony fungus growing in the projection tube antifreeze.
I had a TV repair friend that used motorized hand truck and motorcycle ramps to move the beasts. A HDTV rear model he installed weighed 500lbs.
don,t forget the end when sony had the blue blob of death and the defective optical blocks in all the wega sets
th-cam.com/video/DoYDy8Rzimc/w-d-xo.html
I can't wait to see you work on the Scott projection TV :) For years now I've been anticipating you to get to work on it, because to me this is such a radically different and interesting setup.. I can't imagine anyone better qualified than you to get to work on it, Bob. So do get to work on it whenever you can, I for one can guarantee you I'll be watching every episode LOL
I have two now. Problem is they both need new cabinets. Electronics I can handle, but not fine wood work and joinery. I don't have the tools
@@bandersentv or just put the chassis in the console instead of hacking a downer set
@@force311999 Scott power supply and receiver chassis are huge and heavy
I assume these early projection CRTs were pretty ferocious x-ray emitters with 30kV acceleration and focused on such a small spot, and the mentioned 80-100kV ones are well into x-ray machine territory. I wonder what kind of dose you'd get standing in front of that "searchlight" looking unit. Cool little book, the history of display tech has so many oddball solutions that were viable for less than a decade and mostly in fairly high end niches and are now almost completely forgotten.
No. They don't emit any X-rays. Not the CRT any way. You need to hit a metal target to gen x-rays. The HV rectifiers might but they are sealed in a metal box.
@@bandersentv Interesting. I can't say I've ever experimentally confirmed it but i have read that x-rays can be a hazard with electrons hitting glass windows with sufficient energy, but it's completely possible it was overly cautious advice to high vacuum/high voltage experimenters and/or it depends on the specific glass composition.
I forgot that these are aluminized so there is a thin metal surface behind the phosphor. No warning in the CRT data sheets though. Other HV tubes like 1B3 or 6BK4 do have x-ray warnings printed right on them though. I've seen some other youtubers try to detect x-rays coming from TV CRTs with a geiger counter and got nothing. Now it could be that those detectors are not sensitive enough or any x-rays too weak.
@@bandersentv I don't think the usual Geiger counters are very sensitive to X-rays. Other types of detectors can work better.
I like to magnify 7 inch tv by watching your 7 inch repair vids on my Samsung 4k bigscreen. You zoom in and the picture is 3 feet across! I never see the scan lines. Resolution is great even at 3 feet Ha- Ha ! I have read that the mirrors on projection sets are front silvered and if you use a normal rear silvered bathroom mirror the set will not focus. I also read the mirrors in DLP projection tvs found on the side of the road are front silvered and may be a cheap resource. I had a Samsung DLP and they had a great picture until 4 K came out. Interesting vid as always. I think I bid over $200 for a Zenith flashmatic flashlight this year on ebay and lost.
The thing about normal rear silvered mirrors is that there is a reflection from the surface of the glass in front, that double reflection messes up the optical design. A shaving mirror is no where close to the curvature accuracy needed for this sort of optics. The front surface mirrors are very easily damaged, even just exposure to the air will have an effect in time. First surface mirrors are used in the large telescopes and need to be re-silvered every five years or so.
all projection sets are front surfaced mirrors so they are a good place to find mirrors
@@notimetolooz9655 its like the refection you get from a window that has double glass in it
I squirmed watching that device balance on the cardboard box. Now I have anxiety. ;-)
Minor nitpick here, but the electronics brand is spelled "Philips" (with one L). Phillips (with double L) is the brand that makes cross-head screws. Philips used the "Norelco" brand in the USA to avoid mixing the two companies up and to prevent a trademark lawsuit.
Phil Nelson has an article on his working Emerson 609 projection set using the protelgram unit. I'm currently working on restoring my Emerson 609 but sadly I will have to find a new 3NP4 as mine has a line burnt straight across the face of the tube.