or Connect
CHUD.com Community › Forums › DVD, HOME THEATER, & GADGETS › Chewer Tech › My rear-projection tv is getting darker
New Posts  All Forums:Forum Nav:

My rear-projection tv is getting darker

post #1 of 17
Thread Starter 
It's been happening gradually, but lately my Panasonic rear-projection tv image is getting darker and darker. I have to turn the brightness all the way up to get a halfway decent image. It really seems to be more of a contrast issue, but the only levels it has are Color, Tint, Brightness, and Picture. "Picture" seems to be the replacement for "Contrast", but it doesn't operate the same way -- it "intensifies" the image compared to how contrast levels out the blacks...

At any rate, does anyone here have any experience changing bulbs out in one of these things? Will I be forced to call in a professional? Any links to good sites with more info about this sort of thing? Any recommendations wouls be appreciated.
post #2 of 17
I have sold many projection TVs at work and I've always been told to let professionals do all the bulb changing. However, I've never done it myself, and I know there are many things that "professionals" charge a lot for that are very simple to do. Another thing to be wary of -- from what I understand, the bulbs are VERY sensitive to the oils in our skin, and touching the bulb with a bare hand can result in a dramatic decrease in it's life. What kind of projection TV is it? DLP? LCD? I know with the standard CRT rear projections, you will most likely have to re-align the "guns" after replacing the bulb -- something you probably already knew. At any rate, I don't know how hard (or not hard) it is to replace a bulb, but it's probably easier than people make it out to be.
post #3 of 17
If it's a CRT rear projection, there aren't any bulbs that need replacing as the CRT tubes (guns) themselves generate the light for projection. Embrodak is correct however that when the guns are replaced, they have to be realigned precisely. Definitely the job of a professional. My experience with digital projectors (DLP/LCD/LCOS) is strictly with front projection only, but I would imagine that the process is essentially the same for rear projection sets. It should be just a pull out and swap procedure. Embrodak is also 100 percent correct about not touching the bulb or surrounding material with your bare fingers. From your description of the light drop-off, it definitely sounds like you have a DLP or LCD rear projector. These projectors generally suffer from a noticeable decrease in brightness in the first few hundred hours of use which stabilizes after that. Light loss from CRT projectors tends to be more gradual.
post #4 of 17
Thread Starter 
CHRIST, I LOVE THE INTERNET.

Well, I HATE calling repairmen, so I did a little research on my problem and discovered that most tvs produced after 1996 have built in "serviceman" setup modes that you can access, enabling access to all sorts of inputs not available on your standard setup screen. I found the one for my Panasonic, and, after carefully checking what was what, I was able to fix the brightness problem myself. The picture looks as good now as it did the day I bought it.

It seems the default brightness setting had been knocked down to 40 out of 200. Nothing on the regular setup menu (including reverting to factory default settings) would fix it, but this internal "serviceman" menu did the trick. I set it to 100 out of 200, and voila! Everything seems back to normal. While I was at it, I tweaked the sharpness and contrast just a bit, and it looks great.

Thanks for the suggestions here, guys. Much appreciated.
post #5 of 17
Jacob, is there a link that you could post showing a list of models that have such "serviceman" controls?
post #6 of 17
Quote:
Originally Posted by JWinge1, Napoleon in Rags
Jacob, is there a link that you could post showing a list of models that have such "serviceman" controls?
http://www.panny.tv/tweaks.htm?KeohiHDTV

Note - going into serviceman mode automatically voids your warranty with Panasonic. Adjustments should not be made before you record your TV's original settings. I would also recommend purching the Avia Calibration DVD to help you make adjustments. If this stuff seems a bit scary (it did for me), you might want to hire a professional calibrator.
post #7 of 17
Here's a good TV question: I bought a Samsung 27" (4:3 ratio) HDTV about 9 months ago. Right out of the box, I noticed that anytime I used anything in progressive scan that the image gets cut off on the extreme right and left edges. Movies, XBOX, Gamecube....doesn't matter. Anything that's pro-scan suffers. My buddy has the same problem with his 32" (again, 4:3), so I think I understand why it happens. I imagine that it has something to do with the fact that 480p and higher screen resolutions were meant to be viewed on a 16:9 TV, so there are just too many lines of resolution to be viewed all at once on my 4:3. I called Samsung, and they said the problem was something called "over-scanning" and that it was something that could be adjusted via the settings inside the set itself. Is it something that would be accessed through this "serviceman" menu that Jacob discovered?
post #8 of 17
Quote:
Originally Posted by Embrodak
Here's a good TV question: I bought a Samsung 27" (4:3 ratio) HDTV about 9 months ago. Right out of the box, I noticed that anytime I used anything in progressive scan that the image gets cut off on the extreme right and left edges. Movies, XBOX, Gamecube....doesn't matter. Anything that's pro-scan suffers. My buddy has the same problem with his 32" (again, 4:3), so I think I understand why it happens. I imagine that it has something to do with the fact that 480p and higher screen resolutions were meant to be viewed on a 16:9 TV, so there are just too many lines of resolution to be viewed all at once on my 4:3. I called Samsung, and they said the problem was something called "over-scanning" and that it was something that could be adjusted via the settings inside the set itself. Is it something that would be accessed through this "serviceman" menu that Jacob discovered?
Try using the "Zoom" feature on your TV or DVD player. That should make things better. The serviceman option is best for rear proection TVs and not a CRT like yours. CRTs do not need twaeking out of the box like the RPTVs do.
post #9 of 17
Quote:
Originally Posted by theroyle
Try using the "Zoom" feature on your TV or DVD player. That should make things better. The serviceman option is best for rear proection TVs and not a CRT like yours. CRTs do not need twaeking out of the box like the RPTVs do.
The zoom feature sadly does nothing. In fact, it makes it worse. Alas, it would seem there is nothing I can do.
post #10 of 17
Quote:
Originally Posted by Embrodak
Here's a good TV question: I bought a Samsung 27" (4:3 ratio) HDTV about 9 months ago. Right out of the box, I noticed that anytime I used anything in progressive scan that the image gets cut off on the extreme right and left edges. Movies, XBOX, Gamecube....doesn't matter. Anything that's pro-scan suffers. My buddy has the same problem with his 32" (again, 4:3), so I think I understand why it happens. I imagine that it has something to do with the fact that 480p and higher screen resolutions were meant to be viewed on a 16:9 TV, so there are just too many lines of resolution to be viewed all at once on my 4:3. I called Samsung, and they said the problem was something called "over-scanning" and that it was something that could be adjusted via the settings inside the set itself. Is it something that would be accessed through this "serviceman" menu that Jacob discovered?
Thats normal on most crt RPTVs. You can change it but you cant change it that much. Then it will mess up alignment. There was more, I researched everything when I wanted to buy one, now I forgot.
post #11 of 17
I'm thinking of getting a rear projection CRT next month as a replacement for a run-of-the mill 20 inch TV, but have a couple of questions for the chewers who own/know RPTVs.

Does burn-in pose a huge risk? I know it's possible, but has anyone had it happen, specifically with channel logos or video games?

Is there a huge difference between 50hz and 100hz? I always assumed the latter would give a clearer, flicker-free picture, but from what I've read online, people have had more flicker problems with the latter.
post #12 of 17
When I first got my 43" Hitachi CRT RPTV, the factory settings came with a significant amount of red-shift. It was bad enough that in a pitch black room, when the screen displayed a black screen (like right before a movie starts), the screen would glow with a dull reddish tint instead of plain black.

Thanks to a few home theater forums, I was able to access the service menu and dial down the red-shift to normal. Aside from that, I haven't done any more tweaking because you can seriously fuck up your TV if you don't know what you're doing in there.

I wish I had the cash to get it properly calibrated. It looks okay for now, but I know I can get a big improvement for a couple of hundred bucks.
post #13 of 17
Thread Starter 
Quote:
Originally Posted by Quatermain
Does burn-in pose a huge risk? I know it's possible, but has anyone had it happen, specifically with channel logos or video games?

Is there a huge difference between 50hz and 100hz? I always assumed the latter would give a clearer, flicker-free picture, but from what I've read online, people have had more flicker problems with the latter.
I've never had any problem with burn-in on the RPTVs I've owned, and I play tons of games and widescreen dvds that leave the black bars on top and bottom. As long as you pay attention and don't leave a single, unchanging static image on the screen for hours at a time, you shouldn't have any problem.

I'm afraid I'm in the dark about the hz issue, though. Don't even know what mine is...
post #14 of 17
Thanks for the reply, Jacob.

That settles the major problem I had with getting one.
post #15 of 17

I have the exact same TV, where did you find the serviceman setting. Thanks in advance.

post #16 of 17
Quote:
Originally Posted by Jacob Singer View Post

CHRIST, I LOVE THE INTERNET.

Well, I HATE calling repairmen, so I did a little research on my problem and discovered that most tvs produced after 1996 have built in "serviceman" setup modes that you can access, enabling access to all sorts of inputs not available on your standard setup screen. I found the one for my Panasonic, and, after carefully checking what was what, I was able to fix the brightness problem myself. The picture looks as good now as it did the day I bought it.

It seems the default brightness setting had been knocked down to 40 out of 200. Nothing on the regular setup menu (including reverting to factory default settings) would fix it, but this internal "serviceman" menu did the trick. I set it to 100 out of 200, and voila! Everything seems back to normal. While I was at it, I tweaked the sharpness and contrast just a bit, and it looks great.

Thanks for the suggestions here, guys. Much appreciated.

Where did you find the serviceman setting? Thanks

post #17 of 17
Quote:
Originally Posted by meckismicki View Post

Where did you find the serviceman setting? Thanks

Yeah 7 years ago, where did you find the serviceman setting?

New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Chewer Tech
CHUD.com Community › Forums › DVD, HOME THEATER, & GADGETS › Chewer Tech › My rear-projection tv is getting darker