Tube ID

[timmy]

The variable cap is 25-280 pf the other 10 pf runs to both side of the verticle output transformer like a circle. With a tap coming from the flyback.

[old_tv_nut]

Originally Posted by timmy

... the other 10 pf runs to both side of the verticle output transformer like a circle. With a tap coming from the flyback.

I'm not following that. I see the right side connected to the horizontal yoke winding and flyback, but where does the left side circle back to the vertical? Does the left side go off to a video or AGC section? In that case, it is probably just a pulse shaper for input to the circuit it goes to and the the connection that goes back from there to the vertical may be carrying an unrelated pulse. (??)

[timmy]

Originally Posted by old_tv_nut

I'm not following that. I see the right side connected to the horizontal yoke winding and flyback, but where does the left side circle back to the vertical? Does the left side go off to a video or AGC section? In that case, it is probably just a pulse shaper for input to the circuit it goes to and the the connection that goes back from there to the vertical may be carrying an unrelated pulse. (??)

Ok you should be able to see the rest of the circuit.

[timmy]

Here's the pic.

[Yamamaya42]

Originally Posted by timmy

Here's the pic.

blury

[old_tv_nut]

Originally Posted by timmy

Here's the pic.

It's the lines that go vertically off the top of your picture next to the CRT that I'm wondering about. Is that where the "circular connection" to the vertical output transformer occurs? What is up there?

[timmy]

Originally Posted by old_tv_nut

It's the lines that go vertically off the top of your picture next to the CRT that I'm wondering about. Is that where the "circular connection" to the vertical output transformer occurs? What is up there?

hopefully this shows more.

[old_tv_nut]

Originally Posted by timmy

hopefully this shows more.

OK, so it's going to G2 on the CRT. Can't read the value of the cap attached to G2, but if it's much bigger than 10 pF, then the 10 pf and 680ks appear to be loading the horizontal yoke winding. You can go ahead and try 12 pf, and if it does something weird like change the width or retrace time slightly, you can add 82 pf in series to bring the total back close to 10 pF.

[timmy]

Ok the g2 cap to ground is a 22pf I guess that's the cap you are referring to. If the yoke is being loaded what am I going to see, is it the difference in the width or retrace lines.

[old_tv_nut]

Originally Posted by timmy

Ok the g2 cap to ground is a 22pf I guess that's the cap you are referring to. If the yoke is being loaded what am I going to see, is it the difference in the width or retrace lines.

Well, I have reached the limit of my knowledge. The 10 pF going to a 22 pF looks like a pulse voltage divider, but I don't know why you would want a pulse on G2. My guess is that the value of the 10 pF is not super critical, so if you only have 12 pF, give it a try. Still surprised you can't find 10 pF caps.

Maybe someone else can figure out what's going on here.

[old_tv_nut]

Just dawned on me that it may be a negative pulse, providing horizontal retrace blanking...not sure.

[timmy]

What would be the closest match for a 4.7nf cap . Got a bumble bee cap with this low value but I don't see a 4.7nf on the list of caps from just radios that is available.

[Yamamaya42]

Originally Posted by timmy

What would be the closest match for a 4.7nf cap . Got a bumble bee cap with this low value but I don't see a 4.7nf on the list of caps from just radios that is available.

https://www.mouser.com/ProductDetail...WPELGYiw8B8%3D


just 1 of many they have

you did not mention the voltage, i just picked 600 at random

[timmy]

Does anyone know if there is an allowance for a mica cap to drift, like no more then a certain amount above the face value of the mica ?

[timmy]

Anyone ever seen one of these and or what would be the benefit in using it ?