Hello New Friends...Happy to Join! - Videokarma.org TV - Video

Chris K · #1 06-27-2022, 06:48 AM

Hi everyone, my name is Chris K. I need to confess in this introduction, I'm a little intimidated by vast knowledge base here and the presence of the well known experts in the community of vintage electronic resurrection and restoration. I do not count myself at anything close to that level in fact, I'm really a novice having only dabbled in this for a couple of years. I am not, however, a science newbie. I've been a biology researcher and university professor for 30+ years so I do have some basic background in the physics of electronics and electromagnetism. I'm plodding through how to read a schematic and identifying parts and circuits.

I restored about a dozen vintage radios, mostly vacuum tube stuff, and then moved on to vintage TVs. I need to give credit to the community of YouTube restorers for getting me so interested in this. I subscribe to several channels...Paul Carlson...Bob Andersen...Shango66...David Tipton... Buzz1151...Radiotvphononut...just to name a few. I am nowhere near the level of what these experts can do, except maybe cabinet restoration as I've been a woodworker making high end pieces...reproductions of vintage styles and, for the past 15 years, acoustic, flat top guitars. I do value and appreciate them for the insights and for the budding passion they sparked in me for this great hobby.

Anyway, I'll have many basic questions! I've restored a Philco Seventeener, a couple of Zenith TVs and I'm currently working on a 1948 RCA TS-721 that has me so frustrated! I've watched bandersen restore on but he got a picture and a raster after getting high voltage to the 10" CRT almost out of the gate. I'm stuck here. The tube tested fine...no internal shorts and the emissions were good. I've got high voltage and accurate voltage in every CRT pin socket. Still no light from the tube. I'll post below in the regular forum section.

Anyway, great to be here and I hope I don't offend anyone with the poor quality of my work at this point in this hobby. I'm doooin' my best!

Chris

electronjohn · #2 06-27-2022, 08:30 AM

Welcome to VK!

Electronic M · #3 06-27-2022, 10:21 AM

Welcome. Have you adjusted the ion trap? If so you may want to make the grid less negative with respect to be cathode...The bias on point of each CRT is going to vary from the one in the sample set the schematic was made with.

Chris K · #4 06-27-2022, 10:34 AM

The ion trap (IT) is an electromagnet on this set and the adjustability is left to right and on a pivoting swing that is perpendicular to the neck of the tube. There is also a metallic ring structure that slides over the back of the tube and is positioned somewhere behind the IT. It's a passive component. Is this used in conjunction with the electromagnet IT? I was watching shango's resurrection of a late 40s Philco this past Saturday and the tube in that TV had the exact same ring part and I recall he called it an ion trap as well. He positioned it on the neck right in front of where the CRT pin socket plastic housing stopped on the tube. Are both the electromagnet ion trap and this ring part used together to aim the beam do you think???

Electronic M · #5 06-27-2022, 11:01 AM

Quote:

Originally Posted by Chris K

The ion trap (IT) is an electromagnet on this set and the adjustability is left to right and on a pivoting swing that is perpendicular to the neck of the tube. There is also a metallic ring structure that slides over the back of the tube and is positioned somewhere behind the IT. It's a passive component. Is this used in conjunction with the electromagnet IT? I was watching shango's resurrection of a late 40s Philco this past Saturday and the tube in that TV had the exact same ring part and I recall he called it an ion trap as well. He positioned it on the neck right in front of where the CRT pin socket plastic housing stopped on the tube. Are both the electromagnet ion trap and this ring part used together to aim the beam do you think???

The electromagnetic part on the swing sounds like the electromagnetic focus coil. (The passive part closer to the socket sounds like the ion trap.)
The focus coil is a separate device from the ion trap. The focus coil effects focus (beam spot size) and centering of the image. When you have a raster you adjust focus (electronically) and adjust position of the focus magnet to achieve centering and eliminate neck shadow at the edges of the screen.

Titan1a · #6 06-28-2022, 10:18 PM

We're people just like everyone else. Most people here are the "salt of the Earth" type and are usually very approachable. You treat people right and they do the same. They know their stuff and are almost always correct. You'll learn a lot by reading posts. In the event they error they''ll admit it readily but that is a really rare bird!

Chris K · #7 06-30-2022, 06:03 AM

Thank you for the generous welcome Titan1a. It is very good to be here. Hopefully I've moved past "recap everything and see if it works" to some real diagnostic sleuthing. Schematic analysis and discovery is much more fun!

DavGoodlin · #8 07-20-2022, 12:33 PM

I have given sets away that I almost fixed, if only to have a fresh pair of eyes on it. Its easy for the next owner, as he has not seen it before.

I like helping anyone learn, because I have many projects Ill never start, I want to give away anything viable to someone who will not scrap it..

Welcome to VK

Titan1a · #9 07-23-2022, 12:08 AM

It HAS to have TUBES. Glow in the dark and warm in the winter. Warm sound and great picture. Solid state is for pocket radios/TVs.