Tip & How-To about Televison & Video
Over time the Blue CRT in your projection screen produces a thin layer of fungal growth over the top of the tube. This attracts dust particles and as they collect they blocks the light from getting to your screen. This seems to happen with only blue CRT's. To clean it remove lenz and use a damp terry cloth with a water and bleach solution. Wipe the convex part of the tube untill it is free of all dirt and fungi. Replace lenz and get ready to enjoy a very sharp picture.
Posted by Willard... on
Jun 09, 2011 | Mitsubishi VS-6047 60" Rear Projection...
Oct 20, 2010 | Samsung Televison & Video
Aug 02, 2010 | Samsung HC-R4755W 47" HDTV
Hello....I have been working on these (and it's Samsung counterpart - HCM4215) for about as long as they have been on the market. I have ran into this problem on the blue and green CRT many times. Most of the time it is a bacterial growth in the glycol coolant. This model is notorious for leaky tubes (they have the worst rubber seals ever invented for a CRT), and air bubbles trapped within the tubes which allows for an algee-like growth in the fluid compartment between the screen and the primary lens. If this is the case, you will have to remove and drain the CRT, completely clean the assembly with denatured alcohol, and refill it with glycol coolant. If you have rebuilt these things before, this is probably no new task for you!!
I have also ran into bad components on the CRT driver boards with this model. They have always been the variable resistor for the drive (VR501 1Mohm) or one of the three 1/2W resistors right next to it associated with screen circuit. If you don't see retrace lines, then I would bet on the algee!!! Hope this helps out.....please let me know how you make out on it.
Oct 09, 2007 | Akai PT4298HD Rear Projection Television
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