Tube ID

[Electronic M]

Yes.

[timmy]

Ok well here's the numbers for the verticle oscillator transformer, your number was 920 and my number was 1014k and the other, yours 170 and mine .184k those numbers seem ok compaired to yours. Back to the drawing board.

[timmy]

Tom is it possible for you to tell me what the brightness pot is listed as ,what ohms because someone had changed the pot and the brightness will not turn the screen down and wilth a bright line across it will burn in if I have it on checking voltages.

[Electronic M]

Brightness control is 100K. Ends are connected directly to 120V B+ and Ground, wiper connects to cathode via 270K resistor. G1 connects to ground via 1M. G2 connects to boost. Gun voltages should be 45, 0 and 440.

[timmy]

Originally Posted by Electronic M

Brightness control is 100K. Ends are connected directly to 120V B+ and Ground, wiper connects to cathode via 270K resistor. G1 connects to ground via 1M. G2 connects to boost. Gun voltages should be 45, 0 and 440.

Thanks for this info, it will help.

[timmy]

Well I compaired the voltages, yellow 82 v bright down screen still lit, green 75 v red 472v , orange 285v I assume focus , black and brown heater. No 45v or 0 . The bright pot measures 135k but it's still lit no matter which way it's turned and the 270k resistor is good . I'm wondering if whatever is going on with the brightness has anything to do with verticle. the 120v on the bright pot is there and the other end has a wire from there to the verticle hold pot which is tied to ground.

[Electronic M]

G1 is supposed to be 0V. It should have a 1M resistor connecting it to ground and it also has a cap connecting it to something. It sounds like G1 has become positive with respect to cathode in your set....that will give you 150% brightness regardless of brightness control setting on cathode.

Check the 1M resistor on CRT grid G1 for open and the cap that goes to G1 should be changed or disconnected.

[timmy]

Well that was a good call I have never came across that in the past I haven't worked on these sets as much as you have. The 1 meg tests at 1.3 meg and I clipped the cap and now the brightness works it has one of those bumblebee caps I don't know the value because it has color bands. So I guess I'm on to hopefully find why this verticle is not oscillating. Is the g1 cap even needed .Thanks tom

[Electronic M]

Glad to help.
Regarding bumble bee caps. Can you read resistor color code? And are you familiar with modern capacitor rating nomenclature that uses 2 digits and a multiplier to express capacitance in picofarads (is 102 is .001uf(1000pf), 153 is .015uf, 224 is .22uf)?....a bumbel bee is the modern numbering system encoded using resistor color code...the first 3 bands are capacitance there is usually a 4th grouped with the capacitance bands that I believe is tolerance (I typically ignore it) then there's 1-2 more bands that are further away representing the voltage in hundreds. A single red band is 200V a pair brown and blue is 1600V.

[timmy]

Is this bumblebee cap even required at all ?

[Electronic M]

Originally Posted by timmy

Is this bumblebee cap even required at all ?

I'll have to look at the schematic when I go back to the basement later...I didn't check what it went to only that it could cause CRT bias issues that you were experiencing. I think video was cathode driven so the grid cap could be something like a retrace blanking circuit... I'll get back to you.

[timmy]

Originally Posted by Electronic M

I'll have to look at the schematic when I go back to the basement later...I didn't check what it went to only that it could cause CRT bias issues that you were experiencing. I think video was cathode driven so the grid cap could be something like a retrace blanking circuit... I'll get back to you.

Ok ,thanks

[timmy]

I'm coming up with 2 different numbers for this cap. .047 and 47.
Yellow
Violet
Orange
Grey And blue by its self.

[Electronic M]

Yel violet orange is 473 which is .047, and Sam's says it is a .047 600V. It couples the plate of the video output to the CRT grid so completely necessary if you want video on screen.

Last night I had the things backwards going from memory. The CRT gets its video at it's grid and there's a vertical retrace blanking circuit feeding the CRT cathode off the yoke winding of the vertical...here's some pics.

[timmy]

Ok so I don't know if I'm correct in thinking that the verticle circuit starts at the oscillator then to the output then to the yoke. So the tube oscillates the oscillator transformer then that oscillates the output transformer. I'm trying to get a better understanding of how this seemingly simple circuit works. There is supposed to be 90 volts at pin 6 and there is not and -26 at pin 7 and 22v at pin 3 is present. If the verticle is running then the voltages should be there . At R77 there is 300 v from the height pot up should show some voltage but nothing near 90 v. Even the worst caps I figured there would be something even a 1 inch high picture but there is not just a razor lines across. The horizontal I would have thought would have been the headache.