Steve's AV-56WP74 Color/Tint Problem - Home Theater Forum and Systems -

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post #1 of 5 Old 06-06-10, 08:04 AM Thread Starter
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Steve's AV-56WP74 Color/Tint Problem

Hi Leonard (and all),

I've had some time to play with the new tv and I've got an odd problem, but I think it's one I've seen before and it wasn't that major of a fix so I'm hoping it turns out that way again.

The convergence problem is fixed, the STK394-160s and new related resistors seem to have handled it nicely.

The problem is with the color. It seems I have a tint problem in darker images. It's a subtle problem and it took me a while to work out what I think I'm seeing. I'll do my best to describe it.

On bright images things look fine, nice bright colors, white looks good, etc..

On darker images I think I have a greenish tint. It seems to affect the gray scale more than black, as I can see black - it's just anything dark that's not pitch black seems off.

We have to do some rearranging to accomodate the new big screen so at the moment I have a 37" Samsung LCD hooked up right next to the big screen so I can tune them to the same channels and compare the picture.

Some examples:

The other night there was a space show on History Channel. They were showing the earth in space and on the LCD it was a nice blue marble. On the big screen it was a greenish-blue marble. I could adjust the tint/color and get a nice blue marble on the big screen but then later when they showed people talking the people's skin tone was not right (too red-ish).

Later I found a black and white movie on - it was shades of gray on the LCD, but it seems on the big screen it was more shades of goldish-green. I couldn't really adjust that out, all I could do is move it from goldish-green to more of a red-ish tint.

I have a home theater PC system and I have a client unit for upstairs. On the downstairs main unit/tv and on the LCD upstairs the menu screen for that htpc program (GBPVR if anyone is interested - I highly recommend it, it works GReat!) is a darker blue. Resetting everything to factory defaults on the big screen and then pulling up that menu I get a greenish-blue screen. Again, I can adjust it to get a blue screen but then that upsets the color balance on brighter screens. Actually this has been the most pronounced - the rest of it is kinda subtle, but it's pretty obvious when I hook up the htpc client.

This happens on all the inputs - 75 ohm coax and the big screen's tuner, composite a/v, component a/v, and DVI in so I'm pretty sure it's not an input problem.

Years ago when I was in college a bunch of guys and I rented a big old house and it came with a big old blonde console tv. Nothing subtle about that one, it was GREEN! You could turn up the color but then it was just green with red faced people! It didn't both most of us, but one guy it bugged to death. He finally talked us into splitting a service call just to see what it would cost to fix it (the landlord wouldn't fix it - it wasn't his, the previous owners had left it there). I remember the service guy came out and before long he was leaving and the picture looked fine and the bill was just labor - he didn't have to fix anything, he just had to adjust something internal. I have no idea what he did though. I know these are probably radically different sets, but then again they are both CRT based units so I'm hoping this is as easy of a fix as that repair years ago was. I just fixed a set of this exact model for my brother-inlaw and I spent the weekend playing with it and his didn't have this problem at all, so I'm pretty sure it's not an inherent flaw in the set. If it's not an easy fix though then oh well - I've got $54.27 in the set so if I gotta find another one and start over then so be it . . .

I was planning on spending some time with the service manual tonight to try and figure this out, but I have no idea where to look in it as I have no idea what this problem is called or what would cause it so I'm hoping you can nudge me in the right direction - any input you can provide would be much appreciated!


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post #2 of 5 Old 06-06-10, 07:19 PM Thread Starter
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Re: Steve's AV-56WP74 Color/Tint Problem

Hi Leonard,

I think page 55 of the service manual (part #52105, I gave a link in another thread) where it discusses "WHITE BALANCE LOW LIGHT ADJUSTMENT for SINGLE SCREEN" is what I need to adjust?

Since I don't have a signal generator maybe jumping down to:
(9) Select 8. PP from SERVICE MENU.
(10) Adjust <ADM012> (R offset setup) and <ADM014>
(B offset setup) so that the adjustment result out put
screen in the upper half of a screen becomes black
(11) If the screen is reddish, adjust <ADM012>(R offset
setup) so that the redness is reduced to the
(12) If the screen is bluish, adjust <ADM014>(B offset
setup) so that the blue is reduced to the minimum.
(13) Press [MUTING] key and memorize the set value.

And diddling with the ADM012 & ADM014 values to try to work the green out is the move (after writing down what the initial values were of course)?


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post #3 of 5 Old 06-06-10, 08:43 PM
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Re: Steve's AV-56WP74 Color/Tint Problem

You don't need a signal generator. Just get a test disk for your DVD or BR player.

Looking for me, just google my username. I have used the same one for most sites for many years.
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post #4 of 5 Old 06-06-10, 11:24 PM Thread Starter
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Re: Steve's AV-56WP74 Color/Tint Problem

OK, I played a little bit tonight . . .

I'll need to get a calibration disc, I'll scope them out shortly.

For now I knew what the htpc screen should look like so I used it as a ball park reference.

*) I reset all the display presets to the defaults
*) I then set the screen preset to standard and aspect to full
*) I switched to the htpc on input 1 (running component in) - it was greenish again
*) I entered the service menu, on these sets you do that by pressing the sleep timer
button on the remote and while the sleep timing info is still being displayed on the
screen you press the Display and Video Status buttons at the same time
*) It will display the service menu, you want option "8 PP"
*) It will display ADM001 and the value assigned to it. If you press Channel + it will
move to ADM002, if you press Channel - it will move down one. To change the value
you press Volume + or Volume -
*) Pressing the Back button backs you out and changes aren't saved.
*) Pressing the Muting button will save the value.
*) As you adjust the values you will see the changes on the picture on the screen.
*) In my case I needed to move ADM014 down from an initial value of 37 to 30 and now
things seem much better. I may be a bit blue, but the skin tones look much better and
black and white shots look much better. I'll get a calibration disc and play further.

Hope this helps others!

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post #5 of 5 Old 06-07-10, 10:45 PM Thread Starter
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Re: Steve's AV-56WP74 Color/Tint Problem

lcaillo wrote: View Post
You don't need a signal generator. Just get a test disk for your DVD or BR player.
LOL! Don't get the Monster Tune Up DVD! It's pretty basic I found out!

I got a copy of Avia II on the way, supposed to have more patterns, color filters, etc. so hopefully it'll do more of what I'm looking for.

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