CurtPalme.com Home Theater Forum

k.berger · Joined: 16 Mar 2006 Posts: 84

Guys,

before I am going to barrage you with questions ( Very Happy

), I wanted to share something I accomplished and feel semi-proud of...
When I decided to switch from my Marquee 8000 to Ampro 4200, I decided to improve PJ mount as well (since I had to move it's position anyway).
I think I came up with interesting way to become independent for friend's help in lowering and rising PJ to its position. Take a look at pictures:

The electric hoist is available from numerous on-line places, including ebay (~$80.00) and Amazon (~$100.00). It's the smallest one I could find, with lifting capacity of 420lb.
As you can see from pictures, I had to build the extruded cover (abut 3/4" is enough), because it doesn't fit in standard opening, but it's minor complication, and the whole thing is almost invisible anyway.
In case you wondered, the ceiling and walls are going to be painted brown (about 4 ft surrounding screen are already dark brown).
I used nylon straps for lifting, since they absorb pretty strong mech. jolt when the hoist starts and stops (it actually would be better if it was slower and gentler, but what you can do? It's made in China Smile

).
All in all, the whole thing run me less then $120.00, and works like a charm! I even used it to flip the PJ over from its "normal" position, by lifting it only by it's side (so it hangs sideways), and then manually tipping it slightly towards its back, and lowering it - no problem!

Well, now for another subject - here comes the question for experts:
how do I position Focus Coil on the tube neck? (I suspect that previous owner moved at least R and B Coils...).
I know, the manual says to push it as far forward as you can, but when set it this way, I get the best focus on the very edge of adjustment range, and it's not that great anyway... On the other hand, with electronic focus zeroed, when I move the coil, I can get pretty good focus either vertically of horizontally... somewhat less than "all the way" up front...
So what are my options?

Thanks in advance,

Kris

tse · Joined: 03 May 2006 Posts: 1014 Location: Sweatbucket, Fl.

That lift is nice. I need something like that. Last time I hung the projector it took two of us and a couple of step ladders and it wasn't the safest thing in the world to be doing.

Before I ceiling mount a projector I like to set it up on a table directly under the ceiling mount. The picture is upside down and l/r is wrong but it is alot easier to deal with.

Before adjusting the focus mags it is best to "null" the neck mags (CPC) by overlappin the little tabs with the knobs. Best to pick all that green crap or whiteout stuff off so you can easily make the adjustments. Set your static focus to mid range and slide focus magnets on the neck for best focus. You shouldn't have to move them too much back from the deflection yoke. In other words pulling them back a little is ok.

Scott

k.berger · Joined: 16 Mar 2006 Posts: 84

Thanks Scott!

I think it (the lift) really came out pretty nice, and it really wasn't that much work... I would have taken me far less time if I didn't try at first different idea - I wanted to make the whole contraption removable, attached to the ends of those long pieces of unistrut, and hand-operated. It didn't work, although mainly because hand winch I got was so crappy, it kept slipping when I tried to ratchet the PJ down... It worked fine when lifting it up...
The electric one couldn't be mounted at the end (with lifting cable threaded trough separate pulley), because it has metal bar limiting the angle at which you can pull the cable. It would have to be mounted sideways, and it proved to be too much hassle...

As for focusing (thanks again!) , I pretty much did that... What puzzled me most was the fact, that with CPC magnets zeroed, and electronic focus at 50, I got that uneven focus, best for horizontal being in different position of coil that best for vertical... I just don't know if it's "normal"? And if so, should I pick position where they are both equally unfocused?

I know it's not directly related, but I also just PMed Chip trying to get another Focus Board, since I think the one here has problems - I don't see any effects of dynamic focus adjustments...

EDIT: I actually DO see some change - very minor, and again mostly at the end of adjustment range (for all colors)...

Kris

tse · Joined: 03 May 2006 Posts: 1014 Location: Sweatbucket, Fl.

Hey Kris,

The reason that vertical and horizontal don't come into focus together is the 'stig adjustment is off. We used to use a "tool" at Ampro for setting the CPC magnets because of the limited range of static focus from the focus modulator bd. It will hardly defocus enough to set the CPC mags. Alot of trouble to go to but do you have a way of putting a DC current through the focus mag to defocus the beam? It will make set-up alot easier.

Scott

k.berger · Joined: 16 Mar 2006 Posts: 84

Hi Scott,

well, if you explain it to me at the level of "putting the DC Voltage... For Dummies" Very Happy

, I should be able to do it - I certainly am willing to try... The focus (or lack thereof) is driving me crazy, even more than those subtle lines we discussed before, because but for this problem, it would be really great PJ!
Seriously, I don't really have experience at component level electronics, but on the other hand, I am pretty handy, and have background in physics and math, so I should be able to follow instructions.
Have decent Multimeter, but no scope (always wanted one, but...).
I also have small camera and monitor which I use to see close-up of screen when necessary.

So - "have tools, will travel..."

Kris

**AnalogRocks** · Posted: Tue Jul 01, 2008 4:36 pm Post subject:

Kudos for the rigging Kris Thumbs Up

and an extra Thumbs Up

for that olympic mustache Laughing

k.berger · Joined: 16 Mar 2006 Posts: 84

Thanks!

You should see the ponytail.... Laughing

Kris

**AnalogRocks** · Posted: Tue Jul 01, 2008 5:02 pm Post subject:

I was looking at the electric winches at Princessauto ( farm supply/surplus place) fairly inexpensive. I think you are onto something here. Maybe you can start a trend. Winches and soup strainers. Laughing

Unfortunatly I can't do that here. The people in the apartment above me wouldn't like a winch in the middle of their living room Laughing

k.berger · Joined: 16 Mar 2006 Posts: 84

I bet they wouldn't! Laughing

BUT this one actually fits in between floors (well, not exactly, you can see from pictures that I had to lower the sliding cover about 3/4"). It probably could be avoided, if I put enough effort in building flatter mount for the winch - as it stands, I just used pieces of unistrut I already had, plus I was afraid something like flat piece of steel would buckle under the load...

Kris

k.berger · Joined: 16 Mar 2006 Posts: 84

Hi Scott,

thanks by the way for explaining the relation between Focus Coil behavior and CPC Magnets... Should have thought about it myself! Embarassed

.
Of course, if I played with the Coil with Magnets being nulled, Astig WAS all wrong... Dummy ME! Very Happy

But this leads to follow-up questions:
1. You already started answering - and I hope you will find enough time to share that trick helping to set CPC Magnets - I have had hell of the trouble attempting it, even using external patterns and camera/monitor for close-up view... Now I am beginning to understand why (and why it was so much easier on my M8000).
2. When attempting to position Focus Coil, does its angle (rotation) on the neck matter? Or do the magnets (and field from coils) just "compress" the beam symmetrically in the center of the opening?

Thanks again for sharing so much with all of us,

Kris

tse · Joined: 03 May 2006 Posts: 1014 Location: Sweatbucket, Fl.

Kris,

Your posts have inspired me to play more with my 4200. I originally set it up using the static focus control to adjust the stig and beam centering and got a decent picture. Last night I dug through some old stuff and found the set-up tool for 4200s that I have had for years. None of the tubes were set perfectly. This tool lets you defocus the beam enough to really see what you are doing.

Playing with the magnet position helped alot to get best focus (greeen tube). I nulled the CPC mags and set the static focus to 0 with the tool. The magnet had to be pulled back from the deflection yoke about 1/8" to get best forcus. With the tool switch set to stig position the CPC mag wouldn't make the dots round. I screwed around with that for a while and finally found that if I rotated the mag about 15 degrees CW that the dots would go round with the stig CPCs at null.

Switch the tool to beam centering position and adjusted the CPC mag so the core was centered in the flair. That moved the raster positon so I used the centering rings to move it back where I wanted it. That made a little change to the beam centering so a little tweek was needed on the CPC mags to get the core centered again. Back and forth a couple of times on that and the core was centered and the raster was where I wanted it.

So by now I've probably got you interested in the alignment tool. PM with a snail mail address and a promise to return the tool when you are finished with it and I'll send it to you.

Scott

k.berger · Joined: 16 Mar 2006 Posts: 84

Scott,

THANKS! PM sent!

That little tidbit about rotating the coil (if I understand it correctly) is also VERY important! I am beginning to understand interactions between all those components... I think one of the indicators on how badly my astig. is set (despite my repeated attempts) is that I was barely able to center images using centering magnets...
Funny, overall image isn't that bad, but it's of course not nearly as sharp as I was hoping for, in fact it's worse than M8000!? Crying or Very sad

On the other hand, Ampro sort of proves what some people claim about Marquee - without VP it's difficult to get it to output proper gamma. When I installed HDP almost 2 years ago, it was "night and day" difference! I don't expect anything nearly as dramatic with 4200, in fact as far as gamma is concerned, I think it's almost spot on (didn't measure it yet...).
It all makes the focus/stig problem all the more annoying....

Hope with your help I will finally nail it (and you improved yours too!)

Thanks again

Kris