With perfectly focused Marquee 9500's, I notice that as the contrast gets above 70 or so, there seems to be some flair/blooming that occurs.
I know that this is pretty common to the Marquee line and that the use of 22-22 focus coils can improve this, but I think there is somethhing else that is fundamentally wrong.
I thought I remember reading somewhere either here or on Curts site that mods to the HVPS or PS could remedy this. I thought that maybe CZEddie may have mention this and I would now like to get to the root cause.

Any insight??

Terry

we'll have to wait for MP to weigh in but I have noticed lately that replacing the those 2 cheesy little blue cap's on the VNB's with higher voltage rated ones does wonders for overall spot size and reduces the blooming as well by a considerable degree.
Still, I don't think there is any CRT PJ out there that you can push Contrast to 100% and not get any blooming at all?

Terry, if your referring to the HVPS mod with the 560k ohm resistors some people have noticed not a blooming but that when only one tube would be turned on the other tubes would also be on, enough so that you could see it on the screen in a total dark room. What I had to do was to increase the value of the 560k resistors to the value of my worn out carbon comps, i know this sounds unorthodox and the circuit should remain the same but it fixed that problem with no reliability issues so far.
Not sure if thats what your looking for.

Also i found while testing different op amps that the black level restore resistor coming from the TL071 needs to be adjusted(thanks to WTS for that info), this affects contrast levels which will cause blooming if that level is too high. But It would also mean you would have to increase contrast therefore nulling the resistor change. but it wouldnt hurt to maybe increase it a bit to see if you can raise contrast higher and then see if it affects light output.

Athanasios

we'll have to wait for MP to weigh in but I have noticed lately that replacing the those 2 cheesy little blue cap's on the VNB's with higher voltage rated ones does wonders for overall spot size and reduces the blooming as well by a considerable degree.
Still, I don't think there is any CRT PJ out there that you can push Contrast to 100% and not get any blooming at all?

Thanks for your response to my inquiry.
Perhaps blooming isn't the correct term. It is more like a little smearing comes off the right side of the dot.
I have checked this out on at least 5 different 9500's and Ultras lately that are up to a 2002 VDC Ultra, and they all do the same thing. It happens at slightly different contrast levels but generally above 60. I know, you should have to run above 60 but I still want to get to the bottom of this.
At least 4 of these projectors were very well set up mechanically so I know that thius isn't a CPC, focus or astig issue.
The tubes have been different as well ranging from P19LCP's to P19LUG's so I know it isn't a tube issue.
4 of these units had MP mods, 3 of them the latest greatest. The 5th one stock VIM and neck boards.

Cheesey caps on VNB's, there is an interesting thought. Have a P/N you tried??

I swear someone wrote something about this problem being corrected with P.S mods but didn't explain.

Terry

Terry, if your referring to the HVPS mod with the 560k ohm resistors some people have noticed not a blooming but that when only one tube would be turned on the other tubes would also be on, enough so that you could see it on the screen in a total dark room. What I had to do was to increase the value of the 560k resistors to the value of my worn out carbon comps, i know this sounds unorthodox and the circuit should remain the same but it fixed that problem with no reliability issues so far.
Not sure if thats what your looking for.

Also i found while testing different op amps that the black level restore resistor coming from the TL071 needs to be adjusted(thanks to WTS for that info), this affects contrast levels which will cause blooming if that level is too high. But It would also mean you would have to increase contrast therefore nulling the resistor change. but it wouldnt hurt to maybe increase it a bit to see if you can raise contrast higher and then see if it affects light output.

Athanasios

I read with interest about you changing those resistors.

I'll check out TL071.

Terry

TSE also brought up a point over on curts site. On the hVPS mods that people have been doing. We have been also changing out the caps(1uf and the 47uf) with polypropylene caps which have alower series resistance. this may be why we are gettting that problem. the old caps i think were polyester that have a higher resitance. maybe this is why Mike has not noticed this problem, i am not sure if he also changed out those caps as well.

With regards to the tl071 i wonnder if a less noisy amp would also help like the TLE2071 or the OPA134?

Athanasios

EDIT: Just checked curts site TSE says that the caps wouldnt make a difference.

Hold on a sec there, I never said to just go in and change the value of that resistor, I said you may need to adjust that value but only because you had changed the opamp which required changing the RF/RG resistors. In a stock board there's nothing wrong with that value.

Hold on a sec there, I never said to just go in and change the value of that resistor, I said you may need to adjust that value but only because you had changed the opamp which required changing the RF/RG resistors. In a stock board there's nothing wrong with that value.

Point taken, and i stand corected! Just thought a slight change wouldnt hurt much and might help a bit.

Athanasios

4 of these units had MP mods, 3 of them the latest greatest. The 5th one stock VIM and neck boards.Cheesey caps on VNB's, there is an interesting thought. Have a P/N you tried??Terry MP replaces those caps when he works onthe VNB's so it must be something else your seeing? I only work on the 8500's and have not see that smearing. IT sounds a lot like streaking but that would point to worn out VNB's again?
It migth also be noise on one of the rails, but I would really expect a 2002 Ultra to have the best filtering available on both power supplies? Hopefully Mike or Scott weigh in.