Slight shadow on my Chromacolor II picture - ideas ?

[zenith2134]

I'm probably wrong, but isn't that a sign the CRT is getting up there in hours? Reminds me of TVs which don't focus well for about 15-20 seconds, when they're getting soft.

[Snade]

Originally Posted by jpdylon

I had the same failure on a CCII set I fixed. There is a 10uf / 450v capacitor in the power supply that opens. On most sets its part of the large multi-section can on the lower chassis.

Its failure will cause the exact symptom you're facing.

Jordan, thanks a lot. Could you look at the photos below and tell me exactly where to find this 10uF cap ? Thanks.

Also, if you could recommend an online source to buy the caps, that would be great.

Mark (aka Snade)

[radiotvnut]

The cap is the big round silver can next to the power transformer, located on the flat part of the chassis. The cap will be easier to replace if you remove the chassis.

You can get new caps from www.tubesandmore.com, www.radiodaze.com, or www.justradios.com. You'll probably have to go with individual sections and attach them with terminal strips.

[yagosaga]

Originally Posted by eberts

The effect is called "doming".
Doming is a phenomenon found on some CRT televisions in which parts of the shadow mask become heated. In televisions that exhibit this behavior, it tends to occur in high-contrast scenes in which there is a largely dark scene with one or more localized dark spots. As the electron beam hits the shadow mask in these areas it heats unevenly. The shadow mask warps due to the heat differences, which causes the electron gun to hit the wrong colored phosphors and incorrect colors to be displayed in the affected area.

I agree. I have found this doming effect frequently when I do convergence adjustments with chessboard or cross hatch patterns.

http://en.wikipedia.org/wiki/Doming_%28television%29

In some cases, a new purity adjustment might fix this problem.

Eckhard

[eberts]

Originally Posted by yagosaga

I agree. I have found this doming effect frequently when I do convergence adjustments with chessboard or cross hatch patterns.

http://en.wikipedia.org/wiki/Doming_%28television%29

In some cases, a new purity adjustment might fix this problem.

Eckhard

That set is older than I thought, it has the delta 90d tube.
Doming usually does not affect the delta's, mostly later inline tubes with slotted shadow masks.
Probably the condensor.

[jpdylon]

Here's where the cap can lives:



Its best to pull the chassis on this one. Don't forget to discharge the high voltage before you do.

[old_tv_nut]

In sets with automatic grayscale tracking, you may see contrast and color temperature change for the first few seconds as the filter capacitors in the tracking circuit charge up. However, 20 seconds seems kind of long, and I don't know if this set has that feature.

[eberts]

The blue lateral magnet is on backwards

[Snade]

Originally Posted by jpdylon

Here's where the cap can lives:

Its best to pull the chassis on this one. Don't forget to discharge the high voltage before you do.

Jordan, thanks a lot.

Doug is going to help me, so I won't kill myself.

Thanks again. Snade