Overdriven Reds
 

My hybrid hitachi is giving me hell in the red department.. So the golden yellow issue is apparently due to the color decoding overdriving the red.

Thing is, on a greyscale test, it's perfectly at 6500k. The blues and green are pretty spot on, but the reds are actually driving MORE than if it was a white background.

What could be causing this?

Model, chassis or sams number?

It's a model CT1302, running on the older chassis that is a tube hybrid.

As far as the chassis number though, I don't have that right now, I'd need to take it back apart.

The solid state chassis never had this issue, so it's definitely not a CRT problem. Unless the CRT isn't compatible with the hybrid board.

Yea that number is for a much later chassis. I was going to grab the sams and look at it but i need the right chassis number.

Out of curiosity, where did you find the info for the original SS board? Just in case I ever wanted to re-assemble a TV out of the original chassis to this TV.

its sams 1958-2

Thanks.. I'll try and take apart the TV later next week to get a chasis number.

The overdriven reds are deliberate to get the right spread of hues between red and green with modern phosphors. However, there is no R-Y gain choice or demodulator angles choice that is perfect for all colors, so each manufacturer made their own choices - and sometimes it changed from model to model. To complicate things, camera design changed during the years to get better looking color on monitors with new phosphors as well. So NTSC colorimetry has always been out of control.

PAL (and now HDTV) had the advantage of having the newer phosphors before they started, so the color could be compensated correctly in the camera while straight demodulators were used in the receivers.

Hmm interesting. Is there any way to combat this, say, externally?

On a side note, some colors though, like in this scene, don't look that bad at all.

http://img.photobucket.com/albums/v3...edragon/sb.jpg

Externally, no. If the set has an IC color section, then there is no way to do it internally either. Best you can do then is turn down the color a bit, but if it makes the skin tones too pale you may not want to go there.

Tube sets can be adjusted or components changed to modify the color demodulation.

This one does use tubes for color demodulation, and also uses tubes to drive the CRT. The rest however is solid state.

Another reason I really need to get that chasis number.

In that case, there may be an alignment procedure for the demodulator angles that would improve things.

By the way, looking at your avatar, all the color bars look overdriven, so turning down the color may help (but probably won't fix the very orangy yellow).

Some sets during the "one-button color" days went to orangy yellows like this to reduce flesh tone hue variation. And the cheaper chassis sometimes had no button, so you couldn't turn it off. The extreme cases were described as "the tan cowboy on the brown horse riding into the orange sunset."

Ok, I turned the color down a little, and the red is a little bit better and more tame, flesh tones seem decent, but slightly lost.

Anyways, I did other tests on my TV, hopefully they show my TV still is good!

http://img.photobucket.com/albums/v3...ragon/conv.jpg
http://img.photobucket.com/albums/v3...n/overscan.jpg
http://img.photobucket.com/albums/v3...resolution.jpg
http://img.photobucket.com/albums/v3...gon/test-1.jpg

why not align the side convergence better . Blue doesn't seem to be lining up so good. Inline guns aren't too difficult to get perfect.