Blue lens works, but has a weak projection compared to the green and red lens
My Samsung rear projection television screen has been showing a yellowish hue, and the blues often look green. I tried adjusting the manual convergence. The red works fine, but when I try to adjust the blue, nothing seems to happen. I opened it up and cleaned off the lenses and mirror. I turned the power on, and all three lenses light up, but the blue has a very weak projection in comparison to the other two. Is it possible to fix this repair without buying a replacement part?
If not, how much would the replacement part cost? If anyone has any info or advise to fix this problem, I would greatly appreciate it.
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Re: Blue lens works, but has a weak projection compared...
The most common problem I have seen with these Samsung projo units is the blue CRT (picture tube) failing. They usually form algae on the face of the CRT which means replacement of the CRT or rebuilding it by a CRT rebuilding company. I wouldn't suggest the novice to pull the CRT out because if the wrong mouting screws are pulled you will spill out the cooling fluid within the face of the CRT and that will cause more problems.
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The model indicated does not have a "bulb" as it uses 3 picture tubes.
Examine the picture with color set at zero---stand back and look= if the screen has a mostly yellow (all or part of the screen) you have bad Glycol in the blue picture tube(if need explanation ask) and a look in the lens of the Blue tube will confirm this.
If able with back off and a small mirror look in each lens--red picture, green picture and blue picture.
If the Blue looks like a floodlight with little or no image--bad glycol in that tube.
Here is what to do to confirm what problem is, go to black and white program and make sure color adjustment is turned all the way down to zero.
What you are looking for is what color is the screen?
If it a primary a yellow looking screen (all or most) you have bad Glycol in most likely the blue tube. These sets have a sealed area with a sealed area with Glycol (it is like antifreeze and meant to keep the face of the the three picture tubes cool).
What can happen (usually the blue) is it becomes contaminated with bacteria====note, if blue tube is contaminated you will have yellow screen (red and green=yellow.0
The real easy way to confirm if this is the case is with the back removed and access to the three large lens on top of the tubes look into each lens, if the blue one has no picture and looks like a floodlight, but the red and green have a picture, YOU HAVE FOUND OUT YOUR PROBLEM.
I can tell you if this is the case I can tell you what is involved, this most likely is not a do it yourself repair but i can tell you what is needed.
this unit may have a resistor on the green crt-board that has increased in value. check ohms(resistance) on all crt boards and compare to one another. these will have color bands that inicate value of resistance. you do not need to know color code, just match colors of resistors on each board then measure. you could also have weak green tube. turning down the master screen control located on the fous/screen block can reduce grn. drive. to adjust proper drive for each so the grey scale is correct, turn color to tv all the way down then adjust screen controls on block for black & white picture. when color is turned all the way down, you should not have any green, red, or blue over cast on screen. mch
Compare IC connections with meter = check solder joints to
see if some are touching one another. Tell me exactly what
brand & part number was installed...........T.
PS. The red,green,blue plugs may be mixed up because the green should stay and red & blue move !
Take off back cover--look to see if red tube is lit,if not then voltages must be measured at red CRT circuit board. One way to help diagnose is compare voltages to working tube either green or blue--------Let me know.....T.