Hoffman 7M112 tabletop

[Phil Nelson]

The safety glass is tinted. I thought it was just grubby until I removed the glass for cleaning, but if you photograph it against white, the color jumps out. It's sort of a greenish amber.



After recapping, the TV is working nicely except for a slight horizontal non-linearity and lack of width (see previous test pattern). The air-gap "width" adjuster mentioned earlier adjusts the HV output directly; I can get anything from 8KV to 10KV by turning it in or out, which makes the entire screen image grow or shrink. At 10KV, it's much too small and at 8KV (as low as I can go), it doesn't quite fill the mask horizontally.

I have the feeling that it would fill the screen if I could just correct the linearity, but the TV has no horizontal linearity adjuster. Here's the schematic for anyone who's curious.

http://antiqueradio.org/art/Hoffman7M112Schematic1.jpg
http://antiqueradio.org/art/Hoffman7M112Schematic2.jpg
http://antiqueradio.org/art/Hoffman7M112Schematic3.jpg

Perhaps there's a solution, but I'm not sure how much I can expect from this set. I wouldn't mind the minor non-linearity if it would just fill the dinged-danged mask.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[kvflyer]

Originally Posted by Phil Nelson

The safety glass is tinted. I thought it was just grubby until I removed the glass for cleaning, but if you photograph it against white, the color jumps out. It's sort of a greenish amber.



...

After recapping, the TV is working nicely except for a slight horizontal
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

What timing. I am reading an article in our local radio club magazine and it has reprinted an article written by an Australian collector. It talks about the Hoffman company and specifically says that Hoffman used surplus WWII Plexiglas for the safety glass screen. He also mentions the colour as you have described it.

Interesting!

[dieseljeep]

Originally Posted by kvflyer

What timing. I am reading an article in our local radio club magazine and it has reprinted an article written by an Australian collector. It talks about the Hoffman company and specifically says that Hoffman used surplus WWII Plexiglas for the safety glass screen. He also mentions the colour as you have described it.

Interesting!

You can see it was a lighter tint, where the sun didn't hit it. It must turn greener with age.