CurtPalme.com Home Theater Forum

mp20748 · Posted: Sun Apr 19, 2015 11:04 pm Post subject:

Correction: I meant to say in the previous thread "Barco 909 focus coils" instead of "my particular Barco 909"

After getting my Moome card back after sending it to someone inadvertently, I was able to find out a few other things so far. The FGM does work best with the changes (put the 15K back) along with the other changes. The image is a tad sharper than a stock FGM. Not sure why that;'s the case, but I'm only confirming what I was also told.

The difference in the sharpness depends on the source. My Moome allows me to see the difference, that is not seen on the moome with only the filter changes (I'll post pictures on the changes one day). Because when doing 1080P focus, using the source device is a must. The internal grid is not good to focus at the higher resolutions, especially with the mods. My generator is even better.

So at this point, I'm done with the FGM for now. Mine is really working for me at this point.

mp20748 · Posted: Mon Apr 20, 2015 12:41 pm Post subject:

After much hours on this from darkness to daylight, I've made a few more changes. But the better changes are what's already done to my PJ. Kurt and others had talked about it being the sharpest at some point. And I've even wondered why, to know being convinced it's the changes I've already made to the CLM. I'll post them later some day, but for now, I've added a few more of the same previous changes.

If you've ever changed that capacitors on an aged CLM and immediately noticed the picture was sharper.... the reason is added noise on the rails when the main tants on the CLM go bad. They almost always do on the aged boards, and that is the real and main reason for seeing a sharpness increase after changing those caps.

I've gone s little further on mine to even including the Stig board(s) and adding beads to the lines that feed the FGM.

haireez · Posted: Mon Apr 20, 2015 12:52 pm Post subject:

Mike,

We are following this closely. Can you post some pictures on the changes made?

mp20748 · Posted: Mon Apr 20, 2015 12:59 pm Post subject:

haireez · Posted: Mon Apr 20, 2015 1:20 pm Post subject:

haireez · Posted: Tue May 12, 2015 1:30 pm Post subject:

Mike,

It's about 3 weeks now and we are still waiting patiently for your update.

Any chance you will share with us by end of this week?

Thumbs Up

mp20748 · Posted: Tue May 12, 2015 1:34 pm Post subject:

This week for sure. Getting over a bout of Pelvic Inflammatory something. Painful stuff, but I'm getting better slowly.

I have a bunch to cover on this and a few other things, so keep your eyes open this week!

haireez · Posted: Tue May 12, 2015 1:58 pm Post subject:

Sorry to hear that and I wish you a speedy recovery.

Definitely will wait for your updates soon. Thumbs Up

You're the best Mike!

gregstv · Joined: 27 Aug 2007 Posts: 628 Location: Australia

mp20748 · Posted: Wed May 13, 2015 9:55 am Post subject:

gregstv · Joined: 27 Aug 2007 Posts: 628 Location: Australia

Hope you make a full recovery.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Here's a nice little guide to noise reduction in power supply rails.

It covers both bypassing and decoupling techniques.

http://www.designers-guide.org/design/bypassing.pdf

gregstv · Joined: 27 Aug 2007 Posts: 628 Location: Australia

Also some good information attached. I did quite a bit with these on the Barco 808s. The 17V rail ended up much better.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

One thing I've found to be a consistently recurring issue with the usage of "alternative" focus yokes is that it seems that nearly all of them that I've tried end up having a very limited focal range, particularly in the outer focus zones.

Is there enough range to achieve full sharpness? Yes, if the yoke is placed properly on the neck. But there's no extra range avaiable, and as components age and drift I'd be concerned that the day might come where I can't achieve full sharp focus across the whole screen for exactly that reason.

However, on the other side of the coin, having a limited range of adjustment serves to ensure that the adjustments made within that range are very precise. To put it into computer terms, "the bits are closer together". Higher resolution, you might say.

I think I'm just going to HAVE to break out one of my not fully functional oscilloscopes and rebuild the power supply and get it running properly so I can scope out the whole focus system and see what's going on there. Is the dynamic amp reaching saturation? Is there just not enough magnetic field strength being generated, implying the need fo a higher driving voltage to the coil? Maybe a phasing issue? (I can check that easily, and I do. I have found that it really doesn't seem to matter, as the dynamic focus signal is AC and the static focus signal is DC.)

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Now, regarding cleaning up power supply noise...I have a suggestion.

I have an older non-Ultra Marquee with the older, non-Ultra capable motherboard and backplane. I just got replacements for those,
which are Ultra capable, and will be putting them in in the next day or so.

So I'm looking at the motherboard.

You wan to work on quieting down the power supply rails?

I suggest you do it right on the motherboard. There's PLENTY of room and nearly every rail you would want to clean up
is right there and accessible on the top side. Only the 85 volt rail is even a little bit problematic. That way, every board in the
machine benefits from mods made to one.

Looking at how easy it is to isolate and decouple a rail on the motherboard vs. what a chore it is to do it on, for example, the FGM, makes it a no brainer. Do your power quality improvement mods on the motherboard. Most of them, anyway.

gjaky · Joined: 05 Jun 2010 Posts: 2790 Location: Budapest, Hungary

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

If you put the filtering right by the connector to the board you want to quiet down, say right by the FGM connector, then you still
have an easier mod to perform and I'd bet the results would be about the same. Nearly every voltage trace is right there on the upper layer of the motherboard.

If the filtering is right by the connector then the "antenna effect" would be minimized, and hardly any different than doing the
rail filtering on the FGM, or VDM, or HDM, as long as the filtering for a given board is done as close as possible to the relevant connector.

I don't like to do a lot of mod work on densely populated boards. I'd rather work on bigger boards with more room, fewer
components, and bigger traces. Fewer chances of a screwup are the results.

gjaky · Joined: 05 Jun 2010 Posts: 2790 Location: Budapest, Hungary

It was a long time since I worked on a Marquee, but there are the cages and the tube assemblies over the motherboard, so for example on a ceiling mounted Marquee I'd find easier to perform the mod on the actual board rather then messing with the motherboard deep in the belly of the machine.

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Well, I'm working on several machines all of which are on benches right now, not one hanging from the ceiling.

When the machine is on the bench, it's much easier to do most any mod on the chassis. I would expect that for a motherboard
mod, you'd also probably have the machine down on a bench for easier access.

I've got to make some choices, which mods do I want to perform BEFORE I remount the projector(s)? Because I'm seriously
thinking of mounting a pair of Ultras and not just one, this time around. Blend them and run a 10 foot wide screen.