CurtPalme.com Home Theater Forum

[stridsvognen]

[barclay66]

Hi,

There are two things I'd like to mention:

- Looking at the pictures of Your LVPS I couldn't make out the small extra board that is to be found in later models and is intended to make sure that the filament voltage (plug P14) is held within tight margins. Please see the picture below for reference. Of course Your LVPS model could be so new that the circuit has been incorporated into the LVPS board. But, if You still find the old spindle trimmer for the 6.35V filament voltage You should check this first.

- The capability of resolving a certain resolution could be affected by the peaking circuit on the VIM. If the three additional variable capacitors are tuned in for a specific resolution it could well be possible that other resolutions look considerably worse. Look here: http://www.curtpalme.com/forum/viewtopic.php?p=178247#178247.
If You would like to retune it for Your preferred resolution You will need a good oscilloscope and some reference signal for it.

Regards,
barclay66

[stridsvognen]

I have not tested the filament voltage yet, but i put the LVPS from my non ultra machine, that i know is right, so ill se tonight when it gets dark.

I dont have that regulator board in any of my LVPS.

I dont think the resolving power have anything to do with the vim, like im using my old 02 vim, who resolved 1080P 60hz with no problem.

[gjaky]

Is that 'ultra' as sharp as your other machine? I mean are the magnetics (coils, CPC...) aligned well? Try some lower resolution like 720P and look at the scanlines, if they appear equally thin.

[stridsvognen]

[Nashou66]

[CIR Engineering]

[Nashou66]

[mp20748]

Those pots on the VIM is great for commercial video (graphics), but when used at higher bandwidth signals, the op amp will loose its stability. And that's why the colors will change (that let's you know its not stable). Setting it to any one frequency will not solve the problem. It will still drift because its not going to be stable with that cap on the feedback resistor.

It's not only the frequency that causes drifting, almost any differences or variations in the signal will cause color drifting or color shifting. Just pump in a low IRE window and then step up to the higher IRE windows and watch the windows change colors.

Perfect for graphics presentation, because D6500, hues and color shifting is not that important.

The G90 designers also played around with peaking at the FB/G resistor of the last amp on the BA board with a single fixed cap. A fixed cap was a part of the original design, but I'm sure that after they put that circuit in action and found out that you're not going to get a clean bandwidth performance from an overly peaked circuit, so it appears that idea was not put on the final board work.

[Nashou66]

No, mine is stable on one res. Low or high IRE. It is stable. I have a few years experience with these, hundreds of hours of calibration working on the blend. Ask Cliff what he saw here. the reason the colors change in the one on one pattern is because the resolution changes.

I know you'll argue this to no end . But I know what I know because I know it And So does TSE the designer of that circuit as he states here and in the link Jorge posted.

[mp20748]

I've wondered why you never had a problem with this, when some years back there was someone who had this same problem when calibrating the colors on their Marquee that had the VIM with the Pots.

It was suggested to them to remove the Pots, and the problem went away. It was a long thread on this. Not sure if it was on AVS or here.

I'm thinking it was 1031 but not sure. I'll do a search first before I post my own experience, but without having to do that, I'd like to know what Kurt will find out for himself.. I remember this problem well..

[Nashou66]

Mike it was jarmo, But when we discussed this I put an 02 vim i had here with no peak circuit and I got the same results.

I think the key is setting each color perfectly so not to get shifting when raising brightness or contrast. i have that now. But ti takes few iterations of back and forth of setting the trim pots, looking at the pattern then adjusting Contrast and brightness till no change is happening in doing so. Took a few times but it is possible.

I guess the best way to do this is with a scope at the points Scott mentions above. Input the signal and hook up a two channel scope to each test point and adjust the trim pot to match the input at U14 to the output at U11 for each color. then you know its perfect. But doing it the way I did would also work.

In retrospect since I run a blend I really don't need the peaking circuit. But for those who want to run 1080p@72 its a must.


Maybe some day I'll make a video showing this on the scope.

Nashou

[stridsvognen]

I have been up all night adjusting magnetics and stuff, but i still need to trim focus and stigmator.

so i dont have any status right now, i think its better, at least i now have nice round dots on all 3 tubes.

i will continue when it gets dark again.

[stridsvognen]

My neck boards are 50-2039-01P and have a trimpot in the top left corner, to adjust what?

[barclay66]

Hi,

These neck boards haven't been modified and the trimpots are standard. They control the beam current limiting. Better do not touch them. There is a reason why they are sealed...

Regards,
barclay66

[stridsvognen]

Well WIM back to the one with the trimpots, but have removed the vertical line mod.

But that Wim has a lot of noise on the green, and the pic is a bit unstable.. shaking a bit.

Just had to make a factory reset on my lumagen.. I thought i lost it.. It got all wierd.

i better get some sleep before smoke is getting out.

[barclay66]

You know:

Security = Hours of Sleep / Enthusiasm

I've got lots of proofs on this formula...

[Nashou66]

Do not remove the Vertical line mod, I have no issues on my Vim with those. Nice deep blacks with good Gamma. I do not have the elevated black some see. And this is on Both VIM's I have.

Hope fully yours does not have the issue. You should have done a complete set up and calibration before removing stuff.

Remember to look at the Astig amp and CMM, on mine there is where the strange noises were from.

Nashou

[stridsvognen]

The line mod have the same effect on both my cards. I have been trying both 3-4 times now, and its clear to see how the mod elevate the black, now i can change board and use the same G2 settings, and i did calibrate G2 and colortemp. with both cards every time no doubt that i prefer the black, and black details on the non moddet. but i also get the line.

I will in the ende prefer to remove the line another place, or live with it.

Dont worry i always test more than one time before changing anything, and i always make sure i can revers what i did.

[Nashou66]

Ok, I just find it odd that I see no issues with Black. I use a 2.35 Gamma when I calibrate. And Black is Black. And I have an AC machine which i would think would not do as nice of Black as the LC machines.

Athanasios