DimensionDude
Experienced Member
I never had to deal with projection TVs when I worked in the repair shop, the shop owner always handled them.
Recently, a friend called me to look at his tv. A quick look revealed that one color was missing (green) which led to the discovery that the focus/screen module was bad. After replacing the module, the picture was still pretty bad. Blue halos around bright objects, colors a bit off, etc. I looked into the lens (with a flashlight) and found that it looked murky. I adjusted the focus and screen controls as best I could but the picture was still nearly unwatchable.
I knew that there was on optical coupling/cooling fluid in the lens assembly, but I didn't know that it tended to become cloudy over time. Especially the blue and green. It's called fungus, but it's not biological, it's a chemical reaction between the fluid and the lens housing. Oddly enough, red light suppresses this reaction, so the red gun is only rarely affected. Blue is the worst, and such was the case with this tv.
My friend couldn't stand watching this set so he bought a new one (giant LCD widescreen) and we transported the bad set to my house so I could have a crack at repairs.
I pulled the green gun first and drained the fluid. It looked pretty nasty, yellowish with sediment and clouds. The local electronics shop had replacement fluid on the shelf ($6.45 per 8 ounce bottle, each gun required 12 ounces). Cleaned the lens and CRT face, reassembled and refilled. Performed the same procedure with the blue gun.
Turn the set on, turn the brightness down a bit and let it run for a few hours so everything can stabilize. Convergence is really, really bad. Actually, it was never that great, even when new. Run through the convergence, set the white balance, and now it looks like a new set.
This set is a 7-year old Magnavox 54-inch standard definition. The CRTs were noticeably (but evenly) burned in, may get a couple more years out of it.
Kent
Recently, a friend called me to look at his tv. A quick look revealed that one color was missing (green) which led to the discovery that the focus/screen module was bad. After replacing the module, the picture was still pretty bad. Blue halos around bright objects, colors a bit off, etc. I looked into the lens (with a flashlight) and found that it looked murky. I adjusted the focus and screen controls as best I could but the picture was still nearly unwatchable.
I knew that there was on optical coupling/cooling fluid in the lens assembly, but I didn't know that it tended to become cloudy over time. Especially the blue and green. It's called fungus, but it's not biological, it's a chemical reaction between the fluid and the lens housing. Oddly enough, red light suppresses this reaction, so the red gun is only rarely affected. Blue is the worst, and such was the case with this tv.
My friend couldn't stand watching this set so he bought a new one (giant LCD widescreen) and we transported the bad set to my house so I could have a crack at repairs.
I pulled the green gun first and drained the fluid. It looked pretty nasty, yellowish with sediment and clouds. The local electronics shop had replacement fluid on the shelf ($6.45 per 8 ounce bottle, each gun required 12 ounces). Cleaned the lens and CRT face, reassembled and refilled. Performed the same procedure with the blue gun.
Turn the set on, turn the brightness down a bit and let it run for a few hours so everything can stabilize. Convergence is really, really bad. Actually, it was never that great, even when new. Run through the convergence, set the white balance, and now it looks like a new set.
This set is a 7-year old Magnavox 54-inch standard definition. The CRTs were noticeably (but evenly) burned in, may get a couple more years out of it.
Kent