Film-Tech Forum ARCHIVE: Issue with older Sony Trinitron TV

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Posted by Richard Greco (Member # 2032) on 02-02-2006, 09:54 AM:

Hey guys, I'm holding off on buying a new TV b/c I'm saving up for a really nice one but I have a problem with my current TV. It is a 32" Sony Trinitron made in 1996.

Currently when it shows a very light or white picture on the screen, it shows a green tint. I have adjusted the hues and any other adjustments I could think of. It is a regular picture when a dark section is on screen.

Any ideas on what might be wrong?

Thanks in advance!

Posted by Darryl Spicer (Member # 711) on 02-02-2006, 10:29 AM:

did this just start doing this or has it been doing it for a long time or when you first got the set. You may have to make adjustments down in the brightness control to help prevent this from happening. Another possibility is the set may need to be degaussed. Some sets have a degauss feature on them and some don't. One method that sometimes works is turning the set on and turning off wait about a minute and turn it back on and repeat a couple of times. Another method is to take a magnetic device like an unshielded speaker and pass it across the screen a few times with the set off. But a lot of the magnetic field issues with a CRT screen can also be seen in darker images as sort of purplish. My guess though is most likely the brightness needs to be adjusted down.

Posted by Mark Ogden (Member # 43) on 02-02-2006, 10:33 AM:

How green are we talking here? If it's just a little green in the white areas, you may be able to adjust it out. Somewhere on the back of the set, or possibly inside the cabinet, are controls for R G B drive and bias (some sets have all three, others just R and B). Bias is for the darker areas of the picture, drive for the highlights. You would have to get in there with a tuning wand or a thin 2/32 flathead and try to balance out the color, either by subtracting green or adding red and blue.

If it's VERY green, however, it's more likely a tube that's about to die, or a power supply issue. Either way, you may not have the adjustment range to tweak it.

A problem with residual magnetism that would require degaussing would be evident in the entire brightness range of the picture, both the light and dark areas, and would most likely be concentrated in a small part of the picture. It would appear as a green blob somewhere near the corners or sides. Is this what you're seeing?

Posted by John Pytlak (Member # 331) on 02-02-2006, 10:43 AM:

As Mark notes, if it's an overall green "tint" to the highlights, the bias adjustments to the CRT drive may need adjusting. If it is in only one area of the screen, it may be a "purity" adjustment or need degaussing --- stray magnetic fields are deflecting the beam to the wrong phospors in a portion of the screen. Although bad "purity" is usually most visible with a red only screen, not a white screen.

Posted by Richard Greco (Member # 2032) on 02-02-2006, 11:48 AM:

It is a light but noticeable tint throughout the whole screen on very bright or white scenes. It just started doing this about a month ago, the set is about 10 yrs old. I watched Into The Blue the other day and the very bright scenes had a light green tint to them.

Should I take it to a shop to have it adjusted? Also, please use some laymens terms as I don't know much about TV's

Thanks again.

Posted by John Pytlak (Member # 331) on 02-02-2006, 01:22 PM:

Yes, take it to a local TV shop where they still have a knowledgable technician right there to talk to. Likely just a simple adjustment if everything else has been working fine.

Posted by Bruce Hansen (Member # 281) on 02-02-2006, 06:22 PM:

Please do not put anything magnetic near your CRT. That will magnetize the tube, and give you some very strange colors. You can use a demag coil, that uses AC so that the field is varying, and changing polarity. Turn the unit on about 10 feet from the set, then slowly bring the coil to the set, moving it all around the CRT. Then move the coil slowly away from the CRT before turning it off.

Your peoblem does sound like the screens and drives need adjustment.

Posted by Richard Greco (Member # 2032) on 02-02-2006, 06:26 PM:

I do have a mini-fridge next to it, I got that about a month ago, coulde that be causing some of the issue?

Posted by Mark Gulbrandsen (Member # 72) on 02-02-2006, 06:51 PM:

Probably a blown video IC... located some place before the electron gun driver transistors. I've seen very few driver transistors actually fail... its always something behind them. This was common back in the late 60's when Sony Trinitrons first appeared. Its also a common problem with Panasonics. If its the CRT some techs have whats called a rejuvinator. These pieces of equipment can also be used sucessfully to remove inter-element shorts. But this is a last resort sort of thing as destruction of the gun can also occur.
I sould not mess with the drive controls or screen grid adjustments for the crt if this is something that just appeared one day.

Mark

Posted by Richard Greco (Member # 2032) on 02-02-2006, 07:01 PM:

How much is a repair like that usually? Would it just be better to suffer with it till I can get a better one? It isn't like it is all the time, just on the very bright scenes.

I appreciate all the input

Posted by John Pytlak (Member # 331) on 02-02-2006, 08:35 PM:

The way you described the problem, it sounded like a gradual shift and slight tint, which would be more likely an adjustment than a blown component. A competent TV tech can usually adjust.

Yes, a mini-fridge (compressor motor) right next to a set could have enough magnetic field to require degaussing. Move the set away from the fridge, and turn it on and off a few times (to activate the automatic degausser).

Posted by Mark Gulbrandsen (Member # 72) on 02-02-2006, 09:37 PM:

quote:
It just started doing this about a month ago,

quote: John Pytlak
The way you described the problem, it sounded like a gradual shift and slight tint

I thought so too untill I saw the top line in an above post......

Posted by David Stambaugh (Member # 1102) on 02-04-2006, 10:47 AM:

Try adjusting the contrast (white level) lower. If your set has preset picture settings like "Vivid", "Pro", "Movie", etc. try changing to a different one ("Vivid" = "Torch Mode" and should be avoided like the plague).

This does sound like something that could be fixed by internal adjustments. Computer monitors have this same problem where over a long period of time they might shift greenish or pinkish (now that I think about it, I've seen this mostly on Sonys). Internal adjustments can usually mostly correct it.

Posted by Richard Greco (Member # 2032) on 02-04-2006, 11:30 AM:

On monday I'm going to call a shop and get a price on the adjustments. Thanks for all the help guys

Posted by Brad Allen (Member # 470) on 02-04-2006, 05:31 PM:

Richard, it would be worth a shot to move the frig away from the TV and see if it clears up.

Posted by Bruce Hansen (Member # 281) on 02-06-2006, 06:21 PM:

A CRT that is going bad, and has low emission may show a color tint in very bright areas of a picture. This tint will only be in very bright areas, and will not be an all over tint. If the brightness and contrast are turned down the problem will lessened or go away.