Starting a Restoration on a 1951 RCA 7T111B

[Aperna1985]

I recently picked up an old RCA 7T111B with the KCS47GF-2 chassis from the estate of a RCA electrical engineer. I also got an RCA Gizmo from them. Apparently this set has been sitting for over 50 years and the previous owner either helped RCA invent their line of televisions or invented the color sets I'm not sure. But his son is in his 60s. Anyway I brought it home and I brought it up slowly on the variac and was surprised that I was able to get audio out of it and high voltage. I tried to get a picture but the controls are so dirty that I have to keep turning them side to side to see anything on the screen. I tested all the tubes and have a lot of tubes on order, the CRT tests very strong. So the next move is to pull the chassis and start replacing capacitors. I'm not sure how to get this chassis out. Almost everything is straightforward the only thing I don't understand is how to disconnect the high voltage it looks like the wire is built into the tube then comes back to the high voltage cage where it looks like there's some kind of a plug that's sitting in rubber have any of you come across this before?

[pallophotophone]

After you discharge the HV- a wire from the chassis to the metal fitting at the end of the white wire, grasp the connector at the flange end of the white wire and gently rock it and pull straight up. It will unplug.

[Notimetolooz]

Without looking up the model or chassis just looking at the pictures it looks like that is a metal glass CRT. The "bell" or cone part is metal and it is all at High Voltage.
The HV lead is attached to the mounting hardware at the front of the CRT.
I believe that gizmo on the HV cage is a insulated connector. The wire attached to the CRT mounting has a sort of snap like connector that fits into the insulated connector. That is a bit of a reverse of the more common arrangement where the snap is on the wire coming from the HV cage and the connector connects to a small pocket on the side of a glass CRT.
BTW, the CRT mounting hardware has to have a layer of insulation between it and the rest of the TV. It probably is a sheet of plastic that is brittle by now.

[Aperna1985]

Update I was able to pop the 2 metal parts apart and the chassis is out. I can't believe how many caps are in this thing I have a long road ahead.

[Electronic M]

These aren't bad caps wise compared to a 630 chassis or a early color set.

I've got a KCS-47 chassis laying around after filming this video this sat on Facebook vintage TV marketplace for dirt cheap and on the local marketplace for more expensive... After 2 weeks someone contacted me and wanted just the gutted cabinet...
https://m.youtube.com/watch?v=rQ99Xut9yrc

[Aperna1985]

Originally Posted by Notimetolooz

Without looking up the model or chassis just looking at the pictures it looks like that is a metal glass CRT. The "bell" or cone part is metal and it is all at High Voltage.
The HV lead is attached to the mounting hardware at the front of the CRT.
I believe that gizmo on the HV cage is a insulated connector. The wire attached to the CRT mounting has a sort of snap like connector that fits into the insulated connector. That is a bit of a reverse of the more common arrangement where the snap is on the wire coming from the HV cage and the connector connects to a small pocket on the side of a glass CRT.
BTW, the CRT mounting hardware has to have a layer of insulation between it and the rest of the TV. It probably is a sheet of plastic that is brittle by now.

It has what looks like rubber that goes around the tube. I've never dealt with this type of Tube before, I was very surprised when I reached in to jiggle a tube, and the picture tube arched to my arm. Considering I've never been around a metal tube is there any different precautions when removing and reinstalling it? I have to remove the tube from the cabinet to remove the safety glass from the cabinet to clean some black goop off.

[Notimetolooz]

Do you know what CRT that is?
CRTs of that vintage and size often were tubes made with a metal cone between the glass screen and the glass neck section. There were mechanical problems making a CRT that was all glass that were later solved. The metal/glass tubes were lighter as an advantage at least.

The all glass tubes have a conductive coating (DAG) on the inside that is connected to the HV lead. (Later they applied a conductive coating also to the outside that was grounded. This formed a capacitor that helped smooth the HV charge.)

On a metal/glass tube the metal cone was used as the HV electrode. There is a HV cap (ceramic almost always) in the chassis that smooths the HV charge. The tube shell must be insulated from the chassis and other metal areas. The insulation can also form a capacitor that can hold a charge. It is always a good idea to discharge anything that is or was connected to the HV lead. So that means the metal cone as well as the HV cap in the chassis.
You will want to clean the insulation sheet and other parts but be careful not to damage them.

[Aperna1985]

Originally Posted by Electronic M

These aren't bad caps wise compared to a 630 chassis or a early color set.

I've got a KCS-47 chassis laying around after filming this video this sat on Facebook vintage TV marketplace for dirt cheap and on the local marketplace for more expensive... After 2 weeks someone contacted me and wanted just the gutted cabinet...
https://m.youtube.com/watch?v=rQ99Xut9yrc

Tom I watched your video, I'm actually a big fan of you and Shango. I have a C3 also. I see you didn't unsolder one end before testing for leakage. Did you remove the tubes or anything before checking for leakage?

[Electronic M]

Originally Posted by Aperna1985

Tom I watched your video, I'm actually a big fan of you and Shango. I have a C3 also. I see you didn't unsolder one end before testing for leakage. Did you remove the tubes or anything before checking for leakage?

It probably looked like I didn't unsolder one leg of each cap because of editing (waiting 10+ seconds for each solder joint would probably bore a good part of the audience), but I did unsolder 1 leg of each cap before testing...I did notice if I left the TV chassis plugged into the variac the lead of the cap still connected would leak back to the C3 through the line cord and give some false leakage indication. So I was doing the cheeter cord hokey pokey each time I tested a cap. That line cord leakage was interesting to discover.

Thanks, for watching my videos!

[Aperna1985]

Originally Posted by Notimetolooz

Do you know what CRT that is?
CRTs of that vintage and size often were tubes made with a metal cone between the glass screen and the glass neck section. There were mechanical problems making a CRT that was all glass that were later solved. The metal/glass tubes were lighter as an advantage at least.

The all glass tubes have a conductive coating (DAG) on the inside that is connected to the HV lead. (Later they applied a conductive coating also to the outside that was grounded. This formed a capacitor that helped smooth the HV charge.)

On a metal/glass tube the metal cone was used as the HV electrode. There is a HV cap (ceramic almost always) in the chassis that smooths the HV charge. The tube shell must be insulated from the chassis and other metal areas. The insulation can also form a capacitor that can hold a charge. It is always a good idea to discharge anything that is or was connected to the HV lead. So that means the metal cone as well as the HV cap in the chassis.
You will want to clean the insulation sheet and other parts but be careful not to damage them.

It's a 17GP4 Picture tube.

[Aperna1985]

I ordered my caps for this set and My Zenith last night. I'm not sure if I choose good enough caps. I didn't take the AC ripple into account. What do you guys think? I added the list for the RCA below

[Notimetolooz]

Originally Posted by aperna1985

it's a 17gp4 picture tube.

17GP4.pdf

[Notimetolooz]

Originally Posted by Aperna1985

I ordered my caps for this set and My Zenith last night. I'm not sure if I choose good enough caps. I didn't take the AC ripple into account. What do you guys think? I added the list for the RCA below

As far as I can tell those are fine. They really need to be compared to the specs on the service data however. The cap brands are fine.
If you need to fret over something make it that you connect them correctly.

[Aperna1985]

Hey guys so I'm a little confused with the TV. I replaced all the capacitors, and then fired the set up I have sound, I could actually hear the snow and even the phono Port works. But I have no picture. The picture tube tests very high and has great cutoff, I took the plug off the back of the picture tube and compared all the readings with the Sams and they read correctly, and I know I have high voltage because I took a test lead attached it to the chassis put the other end on a screwdriver and reached into the high voltage cage and I'm able to jump a spark from both the 1B3GT and the 6BG6G tubes inside there. Where else should I be looking. The funny part is if I turn the selector down to phono leave it there for a few seconds then flip it back to television mode I'll get a quick white stripe across the screen that goes away.

[old_tv_nut]

1) your posted schematics are too blurry to read

2) Have you tried adjusting the ion trap?