Roundie left edge purple
 

its about the very 1st 3/4 in a very straight vertical purple edge. Since its on the edge its only show about 6" beyond that on the top and bottom the crt curves and it does not show. The purple is straight that is, it does not curve with the tube.

Tried deqaussing, no help. I tried taking a pic put it is too faint to show up.

It also seems the width is underscanning as the screen seems to blank out at the extreme left edge, maybe the 1st 1/4 inch from the extreme left, the the purplish hue for the next 3/4 the fine. You can see the picture thru the purple hue.

turned the camera on its side and got a close up. this is a B&W, the blue screen is not right, its grey, not sure why the camera is having such a hard time, but you can see the dark area and then the purple

another

opps that was a dupe here is another,

If you adjust the horizontal centering, does the purple shading follow the raster/picture?

How's your HOT and cathode current doing? If you adjust the centering and the shading stays, it's a purity issue.

had not even thought about a purity issue since it was such a nice straight line. I did check the purity on the red screen (just turned down the blue and green drives) with the Heathkit sig gen in the purity mode. guess I should have checked the green since its lacking that for the purple.

Its like the green gun is getting blanked at the very begining of the sweep.

I vote that it's a mild horizontal drive problem causing a ghost foldover, and definitely a horizontal problem of some sort. I strongly doubt purity, although I suppose that's possible if the purity rings and yoke are set really weird.

Charles

horz drive alright, just had the bias set too low, the reduced scan size must have been unequal on the guns, it was under scanning on all, just a bit more on the green. Better pic, and no purple.

it was underscanning on all guns you could see the black edge on all colors just a bit more black on the green.

I will check the anode voltage and HOT current to make sure its in the safe zone.

does it make since that the green gun would scan a bit less due to the contsruction of tube? I am thinking angles of deflection and electron gun placement.

the way it was setup there was under scanning and not over scanning.

cathode current is about 250-260 should be 220 per the schmatic. that is just enough bias to get the full scan. brightness at normal levels.
reducing to low bright low contract gets it down to about 245ma.

low brighness if fine for viewing now. Before it would completly cut off.

High brigtness is good, more than needed now with adjustment.

there is a 5.6 ohm resistor in series with the horz yoke drive wire. I am going to check that to make sure it has not drifted causing too much of a voltage drop and resulting in a loss of scaning. there is also a 'centering" diode across the resistor, not sure what that is about.

Isn't the picture showing ringing symptoms? These are tricky to resolve sometimes. I like to start by completely removing the video to carefully examine a blank raster for uniform luminance. The reason for this is that sometimes periodic luminance variations can get into the video signal -- sort of like barkhausen. If the the blank raster displays the problem then it's a ringing issue in the horizontal sweep stage. If that's the case I'd start with a fresh set of tubes to rule out any quirky stuff like "pinked" grids, neutralization problems, cathode leakage etc. If the ringing is still present after a fresh set of known working tubes then it's either a supply voltage issue or a bad component. Start with checking supply voltages. You may need an oscilloscope to verify the DC voltages are "clean" - no hidden noise. Make sure the scope has a timebase that has variable delay so you can "step" through each scanned line in the picture. Barring any of this being the culprit ... reflecting on the problem reminds me that ringing simply means the energy of the flyback is not being released uniformily during the 15.3 us sweep interval (time it takes the electron beam to move from the left side of the picture tube to the right). So, it could be a non-uniform drive waveform or it may be an impedance mismatch between flyback and yoke. Well ....there are many possibilities. That's the nice part about trouble shooting old color TVs. It makes you think a bit. :D

make sure all your filter caps are up to snuff. Ac leakage can cause similar problems

filter caps seem ok (based on ripple on scope)

still having problem with getting a full horz scan. I checked the HV with the crt bias fully CCW to have zero beam current (I assume that is how to have zero beam current, crt was dark) checked HV was right at 30kv. Schematic says should be 26k max, so I adj horz bias to get back to 26kv. adj CRT bias to get normal CRT brightness back, and now short on horz deflection again.

argh..

there was not 5.6k resistor in the yoke path, AND the Flyback has a trim pot inside the HV cage that has an access hole on the side of of the cage. This is NOT in the schematic and there is no marking on the cage saying what it is for.

I am wondering if it could be a horz width control.

This purpish line is def related to scan width, when I change the format on the converter box to a smaller view (margins on all sides of the programming) there is no issue with the purple in the image, only when the image extends the the end of the scan does it show up. the green is just not scanning quite as far as the blue and red guns. If I could get it to do the normal amount of over scan the issue would be gone.

Seems odd that you have to rely on the HV to be set over max to get the correct scan.

I am going to monitor that HOT current and try adj that pot in the cage to see what it does. Noting the starting point of course.

I have a packard bell thats doing the exact same thing. I have come to the conclusion the flyback is bad because of the high cathode current and everything else checks ok. The flyback gets so hot after about 45 minutes its soft and melty sticky to the touch.

40 ma doesnt seem like that much but at 400 volts or whatever the b+ is it equals some serious wattage and heat to something that really cant get rid of it.

My symptoms are, purplish on the left side, high cathode current and overheated flyback. The anode voltage is fine, it does drop a tad at max brightness and the picture pulls in a little.
The new flyback is sitting in the box on top the set. Maybe this thread will help motivate me and get it together.