I'd use orange drops. If you can find them. Don't be vague. ask for Sprague.
If your voltages are within 15% they are probably OK.

The only difference between a bumblebee (paper dielectric like most plastic body tubular caps of the era) and a wax paper cap (also paper dielectric) is the plastic housing designed to keep moisture out. Both suck equally bad. Replace with any decent film caps. Orange drops are good assuming they aren't too old (I've seen nos 60s specimens that were going bad), new production I favor the maroon ceramic coated Panasonic film caps mouser and digikey sell. Good quality and reasonable price.
The yellow caps some of the radio vendors sell are good to despite some disliking their aesthetic. Just don't melt the body with your soldering iron. They are good for restuffing which is my main use for them.

So would that mean a ceramic disc is out of the question ?

Not recommended, as they tend to drift, unless they are a very stable NPO type.
https://www.allaboutcircuits.com/tec...pacitor-types/

Generally if an original cap in a TV is paper it's a bad idea to replace it with ceramic...you can get away with it in audio circuits and input power line noise bypass caps, but I wouldn't use them elsewhere unless the original cap the manufacturer used was ceramic.
Replace paper caps in TVs with film caps if a sufficiently close modern film caps value exists.
You can get some spooky issues and strange drift from ceramics doing a film caps job.

Do these width coils that are in the old b&w TV sets work , how far do you have to turn them in or out to get a response on the screen.

Yes, for fine adjustment. Maybe 1/2" - 1" from one extreme to the other.

What Tom said ^^ it's important. And in audio circuits, I know that many disc caps were used. But if I need to replace them due to damage etc., I use film in HiFi amplifiers because at high frequencies, the Piezo effect "may" affect the frequency response. Film caps are inexpensive.

In TV sweep circuits, it's probably important to go type for type. I don't try to second guess the engineers, even though they were often badgered by the bean counters

Is there a procedure when setting these b&w tvs up. What is first , the ring magnets on the tube neck and then the width and then other settings on the rear. The sams don’t specify anything.

Not really. They're designed to be plug-and-play when they left from the factory. BUT after repairs some adjustment may be needed to the circuits that were repaired.

The door knob capacitor do they lower in value with age.

No. Ceramic and very stable

Correct, don't expect them to test at EXACTLY 500pf , or whatever, if one does fail, it will be to short to ground, or break apart, which is very rare.

Ok was just wondering because this 500pf tested at 400pf just still looking around why I cannot get the hv higher.

Did you check the items I listed earlier? Especially the grid drive voltage?
Is it running on frequency?
Do you have a stable image?
Swap damper and horizontal output tubes.

I tried another horizontal tube and the image is very good and stable I have no way to check frequency but if I turn the horizontal drive pot the hv will only go up alittle not enough and I get the drive line down the center of the screen and have to put it back down where it was. The grid drive voltage where do I get that from the horizontal output tube ? I’m going to swap the damper and try that. Not sure if this grid drive voltage is listed in this sams I have.I just took a look and it turns out that there is a 6ax4 damper in there but it supposed to have a 6w4 so I have a new one I’ll try.

If you have a stable image, the frequency is correct. I mean use a scope to see the drive AC waveform amplitude.

6AX4 should be fine. Very similar spec to 6W4.

While the 21yp4 is electrostatic the other 21zp4 is magnetic so is there another way to focus this 21zp4 without the focus magnet setup from the factory. The sams shows hv is 10.2kv for the 21zp4 but if anyone has a sams for the cbs Columbia with the 21yp4 electrostatic tube maybe the hv is the same or different I maybe chasing something for nothing if both tubes are listed at 10.2kv. I already tried setting the hv to 10.2kv but it’s clearly not enough because the screen pulls in typical not enough hv.

Timmy, what are you using for a signal source? If you don't have a B&K Analyst, you should have at least a Howdy Doody Test Generator.

I have a bar generator and a good tv signal source but that’s not the issue the problem is this set I’m certain it is supposed to have more hv which I cannot get it plays great other then that.

OK. Try this. After the set runs for 5 minutes, turn it off. Then put two fingers on either side of the coil on the flyback and see if it's hot.
What type of bar generator do you have?

Flyback does not get hot and I have an rca wb-64a

5pf and 10pf mica these are in the hv area so if i were to use ceramic then I assume it should be npo. These micas were not changed since I was not able to find this value with a voltage of 2500v. Ceramic seems like the best way to go. But the sams shows these caps as mmf so this could also mean ceramic I’m thinking. Besides npo what is z5f and z5u

If I go by the sams and set the hv to 10.2kv like it shows the screen pulls in on the left and right about a half inch on each side but I may not have enough to adjust the width to fill it in being the width control only goes alittle bit. And either way the focus should be better but it’s not and it’s said that these big electrostatic tubes have very little focus control. Sams says 305v for focus I go 305-344v and makes no difference. I should try it and rule out if the width will fill it in.

Setting the HV higher will likely cause the image to shrink. It's harder to deflect a more energetic electron.

Now the flyback also drives the horizontal yoke winding so it's not quite so simple. Generally, the more energy you dump into the flyback, the more HV and more deflection so they track.

Really it depends on the design and component matching. There's usually a sweet spot when you get the lowest cathode current, most HV and full width. That's why there are so many adjustments - hor. drive, width and linearity all need to be set properly to get optimal results. That's a bit of a black art.

Well as of now I guess it’s safe to say I got the best sweet spot the screen is stable focus is acceptable and it looks good. I did set the hv to 10.2kv but the width couldn’t open it up was to much. I went over so many times with the both vertical adjustments afc to stabilize the horizontal hold and adjusted the rings on the neck I don’t think it can get any better since these sets will never be perfect. And when I lowered the hv it pulled in on the left and right but if I raised the hv to 13 kv a white line begins to show in the center of the screen 12 -6 position.

I think there's an old trick to increase width by putting a ceramic HV cap across the damper tube

Hmm well I never heard of that but I think I got it as good as it will be so I think I’ll leave it alone and not add any problems 😂

GC made a wafer with built-in cap you could install between the damper tube and socket. I'll post a photo when I dig mine up.

That would be interesting to see. At this point I just wanted to try and make sure all was right so lowering the hv to 10.2 kv down from 12 kv would be the only reason to widen the screen so now it’s at 12 kv with full screen and width and height and linearity are good. How much would that cap for the damper expand the width ?

How would you adjust a 7810 positive regulator to output 5 volts with an input of 9 volts I know a resistor is used but which terminal and how to determine the right resistor.

A 7812 will not regulate with an input of 9V. If you want 5v output I would use a 7805 regulator. They also make 7806 and 7808 and I think 7809 regulators along with 7815 and 7824 regulators. You can use an LM317 as a variable voltage regulator. You should be able to find some circuits on this here web.

+1 .
you can with a couple of resistors make a 78xx series regulator output a higher voltage than it's design voltage (the last 2 digits of it's part number) but you can not make it put out a lower voltage.... unless you burn it out into an open circuit, but few regard a 0V regulator as a desirable part.

Any way to remove potted epoxy from electronics ?