CurtPalme.com Home Theater Forum

Barry · Joined: 01 Feb 2007 Posts: 186 Location: Los Gatos , Ca.

HEAT question.....I have been running the PJ now for a couple of hours to see if there are any problems. There are access holes that allow me to stick my finger down on the CRT face heat sink siding. The heat sink is at room temperature. I upped the 720p refresh rate to 72Hz before the test. I suspect the issue of cooling is more of a "hotspot" issue for the face of the tube as opposed to overall heating.

Second thing...when I stand near the screen I can see some random jitter to the image which I would attribute to sync noise. I am looking forward to seeing upgrades to the boards I can DIY to clean up those paths.

Barry

Dave Lister · Posted: Sat Sep 15, 2007 4:01 am Post subject:

That tank idea we discussed in the other thread may be very useful, to reduce pressure without glycol spraying everywhere all you would need to do it unscrew the cap, the pressure would be relieved and you could check the level to determine how much water vapour has been absorbed and determine when you need to replace the glycol, you could also use a syringe to remove some glycol to check for yellowing/darkening of the glycol.

it may even make replacing the glycol easier depending on how it is positioned:

1: relieve pressure by unscrewing the lid of the tank and the re-tightening it

2: tilt the projector appropriately to allow the glycol to drain from all 3 tubes

3: place a bucket under the tank so when you unscrew the lid and remove it the glycol drains into the bucket

4: tilt the projector to the opposite of above and refill by pouring the glycol into the tank

5: some careful 'jiggling' to get any air bubbles out of the LC chambers and hoses

6: a final top up to bring the glycol level in the tank up to the appropriate level

This looks more and more like a must do project for the ugly Retroblock I have in pieces on my kitchen floor. Thumbs Up

Barry · Joined: 01 Feb 2007 Posts: 186 Location: Los Gatos , Ca.

I am having problems adjusing one CRT (red)to center the raster/image. I run out of range using various combinations of raster shift red and convergence red on green. The physical lens adjusting required to static converge is asymetrical vs. the blue to green adjustment. The result is an image centered on the blue and green but shifted to one side (over scan) on the red.
Since I had all three CRTs out to replace the C- elements, the problem may be related. I thought I might adjust the something magnetic on the neck but only the yoke should have a significant affect on the image position and it looks pretty secure.

Suggestions?

Barry

Ile · Posted: Sat Sep 15, 2007 9:15 am Post subject:

Cpc magnets have effect to raster centerings.

Procedure for astig and finding best position for focus yoke is covered in link two last pages.
http://www.curtpalme.com/docs/BarcoGraphics808s_CRTReplacementProcedure.pdf

When astig is ok you can set R/B raster centerings to 50/50 from menu and adjust rough R/B raster centerings from pots in back end boards.
http://www.curtpalme.com/Barco808_Layout2.shtm
You might have plate over board, but pot position is same.

http://www.curtpalme.com/Barco808_Layout3.shtm

Barry · Joined: 01 Feb 2007 Posts: 186 Location: Los Gatos , Ca.

Ile,

Thanks again for the great guidance. I checked and the CPC magnet assembly was loose on the neck so I assumed it might have shifted during my CRT removal and tried using it to change the red raster center. Does it require differential movement of the CPC magnets to shift position? I looked in the guide and this wasn't mentioned. I moved the assembly as a whole and it seemed to have no effect on position though I will surely have to go back and check and set astig tonight.
I found the red raster shift pot and it didn't seem to have any effect until I turned it multiple turns. I guess I wasn't expecting a multi turn pot. This brought things back to reasonable centering.
Previously you told me how to adjust the master H width pot which I did to get better painting of the screen. I just realized that it expanded the raster to well past the edges so I brought it back within the phosphor area. Is there a control that will widen the range of the image within the raster (other than the one in the geometry menu?) Now the image maxes out at about 85% of the raster which is set with a minimum margin of about 4mm at the widest point. In the guide Guy mentions that some installers will set the raster to overscan while keeping the image within safe limits. Theoretically there won't be any real heating of the tube edge if it is outside the image zone.

On another note I have noticed an erratic jumping of the pic for a fraction of a second where the expands or contracts by ~5% linearly as far as I can see, both horizontally and vertically. Since it is happening on two axes and all three CRTs I suspected something with the high voltage supply. I don't hear any arcing nor is there a pincushioning. Since I recently took all the CRTs out I am going to reseat the connectors I can reach. I reseated all the high voltage leads since they were obvious ones though I am not sure they are routed exactly as they were originally. Any area to check?

I look forward to heating up my soldering iron and joining you on the circuit board noise abatement crusade.

If you ever get to N. California I owe you some very good wine Smile

Barry

oliverg · Posted: Sun Sep 16, 2007 3:56 am Post subject:

Ile is a genius. I owe him some wine too. He has sent me so much information that has ended up being so helpful.

An asset to the CRT community.

Kind regards

Barry · Joined: 01 Feb 2007 Posts: 186 Location: Los Gatos , Ca.

Ile,

I watched it tonight and the jumping was on the vertical only....hmmmmmit is a jump in the vertical amplitude so I doubt it is on the sync....

Barry

Ile · Posted: Sun Sep 16, 2007 12:26 pm Post subject:

Barry · Joined: 01 Feb 2007 Posts: 186 Location: Los Gatos , Ca.

Ile · Posted: Sun Sep 16, 2007 6:31 pm Post subject:

Barry · Joined: 01 Feb 2007 Posts: 186 Location: Los Gatos , Ca.

Ile · Posted: Mon Sep 17, 2007 11:48 am Post subject:

Spotmatic · Posted: Mon Sep 17, 2007 11:52 am Post subject:

A question: in my 1209s (and also 909) there's a menu option "Peaking" in the menu. Disabling this for a given input frequency causes the peaking (adding a whiter side to darker objects, to make them stand out better) to disappear. Is this menu option also available in the 1200 or only on later models?

Barry · Joined: 01 Feb 2007 Posts: 186 Location: Los Gatos , Ca.

Ile,

I am an Electronics engineer but mainly digital. I will try to figure out what those transistors do. But don't count on it Wink

I was wondering what peaking meant. I figured it was circuitry to peak the frequency response on the high end....perhaps that is what it is doing.

Barry

Spotmatic · Posted: Mon Sep 17, 2007 12:05 pm Post subject:

Peaking should be visible in the internal Barco menus/letters. If there's no peaking, the green letters have a perfectly consistent green color. If peaking is added, then the transition from green to black will have a white/lighter colored border... This adds "sharpness" to the signal, but in fact is nothing more than a degradation of the picture.

Edit: on the 909, peaking is always on, for all inputs and all input frequencies. You have to set it to off manually.

Edit 2: removed a very bad error Very Happy

Ile · Posted: Mon Sep 17, 2007 12:21 pm Post subject:

Ile · Posted: Mon Sep 17, 2007 12:31 pm Post subject:

Barry · Joined: 01 Feb 2007 Posts: 186 Location: Los Gatos , Ca.

Which transistors did you substitute? Were they higher BW transistors?

Ile · Posted: Mon Sep 17, 2007 1:27 pm Post subject:

1031 · Joined: 22 Mar 2006 Posts: 657 Location: Finland