CurtPalme.com Home Theater Forum

[cmjohnson]

It's on the "to do" list. No massive rush.

I spent this evening watching Ratatouille on my new Blu-Ray player.


I have to say this about HD native content: It totally raises the bar for projector alignment and setup. If you have your PJ set up
to be really SHARP on true 1080P content, then even a DVD upscaled to 1080P looks almost annoyingly soft and unfocused.

I'm going to have to drop my 9500 soon for some maintenance. I've got a glycol leak in the green and it's also gone kind of hazy in the green coolant chamber so I've got to refurb and clean the whole green assembly, and maybe do the red as well as it seems to have a
little of the same problem as well. And I've got a few other minor mods to do as well. But even with those minor issues, I'm still
getting a sharp enough picture to count scan lines at 1080p.


CJ

[Nashou66]

Well i finaly put in my modded HVPS the one in the pics. The main thing i noticed was an improvement in shadow details. I dont know why and the blacks seem blacker. Maybe the blacker blacks bring out the details in the other low IRE's. Also when it goes form a dark scene to a bright scene the transition is seems faster, and its the same going in the other direction.

Athanasios

[1031]

[Nashou66]

Actually i didnt change a thing. the blacks just got blacker and the shadow details were a little more visible. i left my brightness and contrast where they were.
Athanasios

[Nashou66]

Has anyone had this happen after the HVPS mod shown on this thread. When trying to show individual tube lit up the one next to it will also show a very low level image. this is only when going into the individual tube colors. I have not seen any negative affect on the image at all. here is a thread storted on Avs by TEOnaki:
http://www.avsforum.com/avs-vb/showthread.php?t=976282

Most power supplies before the mod have the carbon comp resistors off of the original value by 50 -150 ohms at least from my own observations, having said that i am wondering if the new resistors that are very close to specs are actually closer than the originals and when the output voltage was set at the factory they were set for the higher valued resistors. And now that the new resistors are almost dead on it has affected the output voltage to G2. Anyone have any ideas?

Athanasios

Edit: Teo on AVs just changed the 560k ohm ceramics to 700k ohm ceramics the actual value he measured of the old removed carbon comps. This solved the anomoly. But i still wonder if there is a way to use those pot to trim the value for the new original spec'd 560k resistors.

[1031]

Yes. Mine marquee act´s like that also.. good to know what caused that.

[Nashou66]

[1031]

Its better not to use trimm pots at high voltage circuits.. use solid resistor, maybe 680kohm is close enough.

Edit: I missundersandet your point.. But i think its better to leave those pots in hvps alone, probably those are for hv-regulation and current limit adjustments.

Edit: i got one used hvps here... Measured those resistors-> all six was close 620Kohm.

[Nashou66]

[1031]

[PaulB]

Interesting!

Just measured mine, readings were;

1. 672
2. 714
3. 715
4. 733
5. 710
6. 737
Average of 713. I can see why their replacement is necessary!

Another question to ponder is did they drift over time or were they already off when originally installed? Proably off when they were installed given the results folks are seeing (my marquee is still in bits at the moment so I can't check) and the fact that there are adjustment pots.

Given my upset about my having already installed the wrong parts on my HVPS, this latest revelation has done little to improve the situation

Arrrrrgggggggggghhhhhhhhhhhhhhh !

Ok, glad I got that off my chest

Surprised other folks haven't mentioned the problem before but maybe there just aren't that many folks who have carried out these mods or maybe they simply just didn't notice?

Just noticed that MP reports that he hasn't seen this problem before on the HVPS's he's modded. Be interesting to see your results Athanasios.
Paul

[Nashou66]

Paul don't worry too much for now it was an easy mod to do so if has to be redon with new values don't sweat it. I have put about 50 hours or more on both mine and have not noticed any problems in the viewed image. It has actually improved in the respect that i used to get times during a movie where the image would go up and down in intensity... only slightly. I noticed it but my friends couldn't catch it and thought i was nuts !


Athanasios

[Nashou66]

Hello, not sure if i should have started a new thread for this but it is related to what has been said here so far with regards to the weird happenings after the HVPS mod. I have been looking at doing component upgrades to all the boards on the marquee starting with the HVPS mod that has caused some here to have intensity problems with the other tubes lighting up brighter than normal while showing only one color. The nex board i was working on was the Focus board. I changed out most of the electrolyitic with higher voltage and the 6 470uf to 1000uf caps which helped with tightening up of some focus drift i had, i had to keep going into the focus for each color to readjust it every week or so. I still have to changeout the sealed square plastic encapsuled caps with better quality ones but now on to what is related to the tube brightness.
I have been going through all the chips on all boards looking for newer replacement chips for most of the op amps in the marquee. I was looking at the specs for the MC34074 and MC34084 op Amps and it seemed that there were better less noisy chips out there so I started my quest and found the Texas Instruments TLE2704 Excalibur http://focus.ti.com/lit/ds/symlink/tle2074.pdf that is a direct drop in for that amp . I wanted the OPA 4134 but they no longer make that in dip style and I did not want to use a chip carrier since they can add noise themselves. Well the first thing i noticed was a big drop in background noise when i was looking into the tubes with a full white field . I had a lot of snow before and even after the HVPS mod, but now it is almost all gone. So this is where i noticed a change in the Higher intensity tube glow from other tubes while showing only one, I wanted to see how each tube faired individually with this new chip and discovered that the tube anomaly is gone!! It is back to the normal barely visible intensity from an non modded HVPS.

I'm not an EE but what would cause this, I am definitely going to change the chips now on my other marquee. For those of you who have this same problem try to change your focus board MC34084's out for the TLE2074's it definitely made a difference to background noise since the new amps are a third less noisy and have a higher slew rate along with double the bandwidth of the MC34084.

If anyone else tries this upgrade let me know your results. I did the upgrade to a 2034-02 board(not sure of exact number).

Athanasios

[1031]

Athanasios thats great news. I must test also those better op-amps.

[Nashou66]

[PaulB]

Many thanks for the information Athanasios. I've ordered up a set in case I decide to proceed with the mod.

Did you also consider changing the three AD835 SOIC's on the VIM to the higher bandwidth AD834? They are $27 each from DigiKey ( http://tinyurl.com/3cok2m ). Would this be a worthwhile mod on its own or would the neck boards also need modding (and if so, just what mods would the neckboards need)?

My neckboards already have CL449A chips so a lot of mods may not apply to me but presumably I would still need to do something to the neck boards if I changed to the AD834? (See MP's comments on the AD834 here at the 'A' place http://tinyurl.com/2t4jwt )


Thanks,
Paul

[Nashou66]

The AD835 have a built in op amp and you cant change them for the AD834's which i think work in conjunction with the TL071's, and i have not been able to find a higher bandwidth replacement for them. But i think we can help out that circuit with the same lower noise version TLE2071 for a replacement of the TL071. Ti has a even quieter chip comming out the OPA 211 that could also replace the TL071. the neck boards also have some carbon composite resistors that should be replace with same value Ohmite ceramics. and I plan on changing the MC34071.81 out with the TLE2071. just waiting for my free sample request to go through. I believe that lowering the noise floor across the entire projector will help any bandwidth mods we may figure out. So I plan on going throug all the op amps and look for suitable less noisy ones that won't need much tweeking with reards to any feed back resistors or any band pass filter alterations, The TLE20xx series can be used all over the marquee i believe but this is not confirmed yet.



Athanasios

[PaulB]

Having had a think about it, I'll hold on the OpAmps for the time being and stick to more general mods as they seem to be a bit easier

To clarify the neck board mods, we're talking R14, R23, R76 and R81 as shown below. this is my own board, modded by Andy ( MadMrH ) who kindly helped me out when my soldering skills proved less than successful ( excellent job Andy, well done and many thanks ). Plus might as well change the capacitors at top left and bottom left as well - thanks Draganm.



For which I need to use Ohmite resistors as follows:
2 x OX330KE 33ohms VNB location R14 & R23
1 x OX103KE 10k ohms R81
1 x OX104KE 100k ohms R76

2 x 33uf 160v 105degree Caps C1 and C26


Thanks,
Paul

[Nashou66]

Yes those are right in the pics.

Athanasios