Stretching a design
 

I was looking through Wallace's Telaides for 1947-1953 Sylvanias. I knew that the 1-108 chassis was used with either a 10MP4 or 12VP4 without any modification other than the CRT strap and some minor adjustments. But, I was surprised to see that the 16" model 1-168 that uses a 16LP4 is the same exact same chassis. The only difference is the RF HV supply and the addition of a 6X4 used in a multiplier circuit to provide 330V for the screen of the 16LP4.

It's surprising to me that the same yoke will work for all three of these CRTs.

Since I have two cabinets and one chassis I still have to decide whether to restore it to a 12" or 10" set. I think the 10MP4 is still good. I don't have a 12VP4. But this discovery makes it quite simple to use a 12LP4. I was planning a similar multiplier supply, but theirs is simpler and cleverer.

I decided to look and see if there was space on the bridge to punch a hole for the 6X4 like there is on the 1-168 chassis. It would make more sense to use a couple of 1N4007s but if I had sense I wouldn't have started to collect old TVs.

To my surprise, not only was there room for the 6X4 but the bridge was already punched to accept a socket for it.

After the 1-168 they moved on to new designs. Seeing a range of 10"-16" CRTs was surprising to me.

I hope to post the schematics later in the week.

John

Schematics
 

Here are the schematics for the 10"-12" 1-108 chassis and the 16" 1-168 chassis. I've circled the additions/changes between the two. Other than the HV, the changes are quite minor.

https://www.msu.edu/~yurkon/Documents/Sylvania9-2.jpg

https://www.msu.edu/~yurkon/Documents/Sylvania1-168.jpg

John