Question about Televison & Video
I have a Phillips Magnavox 54" projection tv that is about 9 years old .I have noticed over the last couple of years the picture is getting darker and darker.I have adjusted the brightness to it's highest setting and it's still dark.I took the back off of it to look inside and you would not believe the dust buildup inside.I noticed 3 big lamps or the guns in the front and they are super dirty. Could this be my problem with the dark picture? And my other question is I know a tv has stored energy inside of it so could I safely blow out some of the dust and use windex to clean the 3 guns or lites.I'm trying to avoid a service call if I can.The tv is getting old and don't really want to start putting money into it.
Thanks for any info you can provide me.
Certainly a cleaning of the face of the tubes would do well to improve light output ... especially if there are smokers in the house . DO NOT try to clean the front surface mirror which is an angle facing down it can scratch and dull easy as the mirror material is not protected by glass...it should not need cleaning as dirt does not fall up . tarry smoke can coat it but does not reduce light output by very much . You can use air to dislodge dirt inside but I use a vacuum near the point of blowing . That will only help with cooling . The lens(big front plastic rectangle) can get quite dirty inside and out .
There is three controls that one can VERRRY carefully adjust to bias the tubes more but the likelyhood of generating overdrive/xrays/shutdown/bad colors is too high .
If you wanna try it PLEASSSE turn color control from menu all the way down to get a black and white picture turn any auto color settings off (don't know this machines options)
Now find on the high voltage divider block
(a small panel may be above main board or at the front or attached to main board, you can order the service manual from 'Servicemanuals.net' for 12.00 to 20.00 bucks mostly on a download for quick delivery ) 6 small adjustment knobs , three will be marked 'FOCUS' and three marked 'BIAS' or 'DRIVE' or 'GAIN' or something like that . there may also be a marking as to color . If unsure turn one of the focus controls and see which color gets fuzzy and put it back approximately where it was .
Now turn first control a small amount clockwise(a guess for brighter) if that color gets brighter with out generating scan lines try to bring next control same amount of turn and then the last one same amount . You will most likely have a non-black and white picture any more , that's OK . Now look for color of white objects in video...note the possible weak color IE: yellowish=mostly RED/GREEN turn up blue till as white as you can get the whites...purpleish = mostly RED/BLUE use green , same with turquoise = need more red .
Now the focus procedure works best with crosshatch but video will do fine...please cover two of the tubes with opaque cloth so only one color seen on screen(PITA to put screen up and down for adjusting all three but can be worth the effort) adjust focus only to get sharpest single color display ... warning , blue will be the hardest to see well ...just look at something with an edge in video .
I have seen these tree tube projectors go well beyond 9 years, how ever , if the set is never off it could well be worn beyond repair unless you salvage some tubes . BE WARNED there are many parts in one of these and symptoms like light to dark from left to right will be bad cap somewhere and so on .
I have had great luck cleaning various models ... I have with Great dismay just threw out my Sanyo that was almost 40 years old and still could produce a watchable picture in a room with out sunlight . Had to make space , I still use the old curved 50 inch screen for one of my DLP projectors .
Posted on Mar 11, 2017
The picture is darker because the dust build up on the lamps or CRTs. I would suggest to leave the TV unplug overnight and clean the lamps using a screen cleaner that works better then windex and clean the mirror that reflects the video to the screen if you can get access to it.
Posted on Mar 11, 2017
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Posted on Jan 02, 2017
Darrt, it`s a big, messy, dirty job but of course anyone can do it if they decide to do so, you MUST get the service manual but it won`t be all that much help, the tubes have to be removed from the set, it`s usually the blue & green that get contaminated, the service manual will explain the procedure to get the fluid out, (which screws not to remove etc.) it won`t tell you to mark the position of each lateral magnet, it won`t tell you that if you move/break the paint on the lateral magnets that your screwed, that yoke position is critical, etc. because they presume your a tv tech. Be advised that you should NOT use Philips coolant when you get ready to refill your tubes, use RCA or some other brand so it won`t repeat the problem, good luck you`ll need it, if you decide to tackle it ask lots of questions on here, BMW Rider
Posted on Dec 11, 2007
Yes, they dim as they age, and you've done well to get 3 years out of one.
Projection TV makers charge an arm and a leg for their replacement lamps. They make it easy to do but as a result the custom lamp assy is expensive. The trick is to just buy the bulb for your model TV from any number of us aftermarket sources at a fraction of the lamp price and install it in the old lamp yourself. really easy.
Posted on Jan 02, 2008
One thing that comes to mind when you say high pitched sound is the HOT ( Horizontal Output Transistor). You may be able to find one at fry's electronics. They are pretty cheap. If you are handy and know something about electronics you may be able to replace it. I am not a TV tech, I have a background in electronics and like to play with them from time to time. Not sure this will help but good luck
Posted on Aug 01, 2008
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