Quote:
Originally Posted by Console User
My 1996 RCA Console Set did new the new eeprom. However, even after the repairman made many replacements of bad capacitors and etc. he really said he couldn't get what you call a very good picture on the set. The Green and Red are okay, but the Blue just kind of goes all over the place. He tested the CRT and he at firs thought it was okay. However, he rechecked it after it was warmed up and find that I have a weak and failing CRT. He said it's probably going to run on borrowed time. He did not want to try to rejuvenate the picture tube as I guess they can then go out shortly after that?
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Any sort of rejuvenation or "cleaning" should be done only when the tube is known to be bad. There's only so much cathode material inside the gun and anything you do isn't going to add any more. The best you can hope for is improving the performance for the balance of the tube's life. Sometimes, it's like burning all your firewood at once: the fire is brighter and warmer but it won't last the night.
I don't know your tech's skill set, but if he's right, then keep a lookout for a tube. At this age, people are looking to dump these TVs for free and you should be able to find one fairly easily. It's new enough not to be a classic and old enough to be a pain to store.
Now, getting back to the TV, a shortcut to finding out if the tube is cranky is to turn the chroma off and see if the B&W picture is normal or not. See if the gray scale can be adjusted and see if raising the blue drive in the serv menu causes premature flaring compared to the red and green.
If it does, swap the blue wire for either the red or green at the CRT socket and reset your gray scale, again checking by eye for the strength of the blue gun. If the problem stays the same (again, leave the color off), then the problem is either the tube or something on the CRT socket (rare). If the problem switches guns, then the big jungle IC on the main board is the most likely culprit.
If the problem seems to be at the tube, check the resistor between the kine output transistor and the cathode pin, usually something in the 2K range. I've seen this happen in Zeniths where that resistor goes bad and does a fine job of simulating a bad tube.
John