FAO - Leonard Smalls - TV Techy Question

Leonard,

I seem to remember you're in the TV related industry. Know about TV specs etc?


I am interested in a couple of things you , (or anyone else), may be able to help me with.

First,

I've managed to get in to the service menu of my Toshiba TV and I'm presented with things such as GCUT, RDRV etc. I was wondering if you knew of somewhere where I may be able to find information on what each one of these is and more importantly how they inter relate with each other. Particularly things like the colour settings etc.

Where could I get hold of a "set up" DVD or Colour Card etc that I could use to try and set my TV to 6500k ?

Second,

My PC monitor is on the blink. It seems like a horizontal sync issue. The whole screen seems to change horizontal position slightly upon turning on the monitor/PC each time and then after a while starts to jump back and forth by a couple of mm horizontally. Also sometimes the monitor just doesn't seem to be able to lock on to the Graphics card out put. Changing display modes/refresh rates etc makes no difference.

It's a nice monitor and I was wondering if it could be something simple like a Cap/Reistor/PSU etc on it's way out. I know monitors are cheap these days, but I'd rather hold on to it and fix it, (get it fixed??) if I can do so for less than say £30 or so.

Any help appreciated.


GTM

 

For the Toshiba service menu settings see here:

http://www.avforums.com/forums/showthread.php?t=46417

(you might want to search that forum aswell, there are many threads about Toshiba TVs and the service menu settings there). Personally, I would be extremely careful when changing any of these values as they can potentially screw up your picture completely. Write down what the current settings are before changing anything

Michael.

 

Michael,

Thanks. I have written them all down. I had a problem with dark scenes being too green. There was always a green tinge to scenes which I know they should have been cold and steely. I started off my adjusting the GDRV as I assumed this was the green gun strength. I was worried about increasing values, so I dropped it to the value that BDRV was set to. It didn't make any difference. Just last night I worked out that it was actually the GCUT that was causing the green tinge to the scenes in question and this has been reduced. However, I've only done it by eye. I chose a "black" background from a DVD intro, which was clearly greenish with the DVD paused. So I adjusted the GCUT down until it started to get a pink tinge to it and finally settled on a setting that made the background as "Grey" as I could get it. Now the picture looks much better.

Even so, I would like to try and get it as "perfect" as possible with the use of the kind of charts that I know TV engineers use to set up a TV. I know there are people around which can get your TV to as near to broadcast standard as the set will allow but they charge almost as much as the TV is worth to do it. I was hoping I could get it nearly right by myself. But I really need to know how each of the settings affect each other and/or the picture.

GTM

 

Messing with greyscale tracking is really a job for the pro's, they've got the gizmos to measure the colour temperature and make accurate adjustments. However, if you are determined to have a go then you should try to get hold of a copy of Digital Video Essentials . This has got the test patterns you need for basic set up of your TV including grey scale tracking.

Use this disc to get the colour, contrast brightness and sharpness set correctly before you start to play with the grey scale. Also spend a bit of time playing with the TV sets' colour temperature control. See if one of the presets gives you a better result as a starting point.

You know that R, G and BCUT control the colour mix for shadow detail. R, G and BDRV adjust for highlights and bright areas of the picture.

Now turn the colour control all the way down so you have a black & white image. Bring up a grey scale image from the test disc. Concentrate your attention on the darker half of the greyscale and make small adjustments to the CUT values first. Once you're happy then move on to the DRV controls to adjust the lighter half of the grey scale. For all these adjustments reducing the values is safer than increasing them.

Don't forget to store the results, then use the test disc to set the correct colour level.

The disclaimer: It's not my fault if you knacker your TV. The above does not constitute advice or encouragement to go beyond the basic user controls.

 

Unfortunately long gone are the days when BBC2 used to broadcast a test screen for most of the day

I'm sure you can get test DVDs though. There have been an extraordinary number of complaints about Toshiba TVs on AV Forums which IMO are really pretty unfounded or perhaps I'm just a bit more tolerant. On mine the image is ever so slightly tilted to the right but it's really only noticable on news programmes which have a caption bar where it's clearly slightly fatter on the left side than on the right but it really is marginal and IMO within acceptable limits.

On the thread I linked above, there are some comments about adjusting the geometry which seem to imply that there's always a compromise in geomtery between the different aspect ratio modes. It seems to me that some people are being extremely picky about it... Needless to say, I haven't touched the settings on my Tosh

Michael.

 

Hex's advice above sounds a little like trying to get a good colour temp and gamma calibration for a PC monitor for Photoshop and I would imagine that the same caveat applies which is that the settings you get to are only valid for the lighting conditions under which you make them so try and do any adjustments in your most likely viewing conditions and also when the set has been on for at least 30 minutes so everything has warmed up properly.

Michael.

 

Try Monsters Inc. I'm sure the THX bit on the DVD would do, mind you I have had a few beers watching the England match.

 

Hex,

Don't worry I wont blame you for anything

That info about the difference between CUT and DRV is exactly what I was looking for. It also explains why reducing the GDRV setting didn't affect the green hue I was getting on the dark scenes. I've adjusted the GCUT now so that dark scenes look tonaly the same as the normal ones. Well as close as I can get it.

One question though. I don't seem to have a RDRV setting. I'm assuming that it is factory preset and the GDRV and BDRV are adjusted accordingly to get the right colour temperature. Would that be correct you think?

A bit odd because there is a RCUT setting.


Michael,

This is only an age issue I have, the set is now 5 years old. When I first bought the set I bought it on the basis that the Toshiba had a more natural colour balance to my eye than most of the other makes. Most seemed to always have an oversaturated red, no matter what I did with any tint/colour settings they had. In fact I find an overpowering red gun a failing of nearly all TVs. If you turn the colour up on most TVs you'll see that the Red becomes saturated a long time before any of the other colours on most TVs.

The only real issue I have with my particular set is the geometry. It can be a bit variable. Apparently it is to do with power regulation not being as good as it could be. What happens is that the width of the picture varies slightly depending on how bright that horizontal part of the image is. Brighter = narrower. It's not noticable most of the time and it's restricted to the top 1/4 of the screen.

GTM

 

GTM,
I wouldn't be surprised if RDRV is fixed. As long as you can adjust the B & G drives though it shouldn't cause too many problems. It might even help simplify the whole process

You're right that most TVs have colour balance that is way off. Manufacturers tune the TVs to look impressive when viewed against competitors product in a shop. The colour temperature is usually too high so that whites look extra bright, and to compensate the colour decoder is tweaked to oversaturate reds.

Frame bounce (variable geometry) will improve a little if the contrast control is set correctly.

Michaels point about viewing conditions is a good one. Get the Video Essentials disc, it goes into all of this in some detail as well as providing reference test patterns to help when calibrating.

Some of the THX discs with the Optimode test patterns might be a useful stop-gap, but the proper test disc is only £15 and gives so much more useful stuff including audio set-up tones. It's well worth the money IMO.

Here is a montage of some of the test patterns from the Digital Video Essentials disc.

Regards

Hex