CurtPalme.com Home Theater Forum

[stridsvognen]

[stridsvognen]

[draganm]

[Tim in Phoenix]

Hello


VIMs are cheap, try another VIM?


.

[stridsvognen]

[mp20748]

[mp20748]

remove three resistors (R205, R206, R208) on the CLM.

[stridsvognen]

I tried the pot, and the 1,5m ohm resistors.

I think the 2,2M ohm will fit fine, i'm not able to go hight enought to see the lines again, and i put a 2 channel pot in series, measure 36k ohm

With the pot set to max. I have to lower my brightness 30, but the red and green gamma is 100% parallel now, they get all weird with just 1,5M ohm. its not only effecting dark level, it messed up the gamma in high level to.

[stridsvognen]

Here is my old and new grayscale, same G2 and Drive settings, with the standard mod 1,5m ohm and with the trim pot, at max, so around 1,85M ohm, the gamma is jumping around at 80% thats gone with extra 35K.

[Nashou66]

Kurt, are you defocusing blue at all? Also lower your Blue drive. Gamma is too low at thr 70-100% white range, suggesting your over driving blue a bit. A few clicks

Also maybe try for a gamma of 2.35, 2.2 is too low for CRT some even like 2.4 to 2.5.

Athanasios

[stridsvognen]

[stridsvognen]

For now i decided to remove the mod, looks like the only thing it do is to cover up the line, like if you have a spot on your white wall, you don't paint the rest off the wall the color of the spot to hide it.

No matter what i did i could see it effecting the pq. I hope someone finds a solution to the fix the line where its created, until then i prefer that line over any resistors on that location on my ViM board.

I will keep the right to change my mind on a short notice..

[mp20748]

I got a chance to look at that line a little closer over the weekend. Here is what I found out:

It's best to not use the line mod at all. The mod as previously mentioned elevates the sources black level above the actual black reference point for best low end performance. So with the mod in place, the absolute best low end performance cannot be achieved.

The line in the image is generated from the Pixel Processor (U106) on the CLM. That chip is the main component for the OSD and Internal Generator. The line itself is generated into the video chain through the "INT/EXT" control line. That is the control that switches the SD5401 from Internal (test pattern) to External source (Moome/BNC's). On the SD5401 it is the "SEL" control pins.

Once the Internal generator is selected (INT-VID), R,G,B video is switched from the Pixel Processor into the video chain. Pressing "CONV" or "#" is two ways to enable the Internal Generator.

However, there is also OSD, that is not generated into the video chain through the same R,G,B Internal pattern. OSD is always active, while Internal Test patterns are switched into the video chain. With the OSD being always active in the video chain, any noise in the Pixel Processor would also be present in the video chain, and that is how the line gets into the image.

The line is not the only noise getting into the image from the Pixel Processor. The three R,G,B Internal patterns from the Pixel Processor also introduces some noise into the video chain. I used to suppress this noise on the generated R,G,B, using ferrite beads. That same noise appears in the image as fog or haze. It also diminishes the sharpness of the image, as what tridsvognen also found during our off-line chat.

The noise on the INT-EXT that produces the line cannot be solved using beads, because it appears as a generated line, not haze or fog.



So for best image or best low end performance, remove or do not install the Line Mod.

[stridsvognen]

With some help from Mike, i was trying to remove the 3 resistors, where the OSD enters in the VIM board, and removing those made the text of the OSD invisible, but the black background showed when pressing any settings.

The interesting there was to see what is black, its not possible to get perfect black, without some video input with quite big gamma correction.

I have very nice black, lowering the gamma from the VP50, but even at10% IRE with a gamma around 2.4, the black is not perfect.

Pressing any button making the black OSD background, will show the absolute black of the crt. Guess thats around 2,6 on the gamma curve, without correction

I hope to find some correction thats able to show black as the absolute black, and lower gamma so fast, that ill get around 2,3 around 5% IRE.

I later played with the OSD on off in the utility menu, and found that if you turn osd off it changes the green G2 settings a little, i could get my gamma curve straight again putting Green G2 2 click up.

It effected the high end of the gamma curve to, but it resulted my green and red being much better.

So my guess is that it removes some kind of noise to the video signal turning it off.

I also think that my 1080P 72hz performance improved without the mod, and osd off.

[Nashou66]

Wait till you get the lumagen and you will have your perfect blacks at 0 IRE and the detail you want at 5% IRE.

The VP50 doesnt have the adjustment for gamma at points like the Lumagens do. Sell it and buy a Lumie, even the old HDP/HDQ will get you what you want.

Nashou

[stridsvognen]

[mp20748]

[stridsvognen]

Mike... Your the man.. i seriously think thats the way to do it.

Some thinking here, and observation. I think that what i see with my 1080P 72hz improvement, is related to better bandwidth, not like its higher, but noise occupying less bandwidth in the video chain, and must be important every where in the video chain.. player scaler cables.

Next, ill try play around with supply polarity, its not without importance to noise in the signal path, And keep all the video chain on the same supply phase.

My Moome card is stuck in custom, so i'm almost exploding here..

What keeps me going, is the many things to adjust on these CRT beasts.. its really challenging, and specially seeing how far it goes.
I know for sure that getting fixed my gamma, specially the blue drop, will improve more on PQ than anything else for now, and might be the thing to tip over the load in favor to CRT. But the Lumagen is not cheep, and this was just meant as fun, but suddenly it gets all serious...

[Nashou66]

[mp20748]