CurtPalme.com Home Theater Forum

CIR Engineering

Not like this is an unknown issue especially on Marquee LC machines, but you guys should ALL check your glycol condition. If you look at your blue tube and see a yellow mess as in the photo below, you really need to change your glycol.

One of my clients sent me that blue out of a 9500LC for me to put an LUG in. The client wasn't even aware that there was a problem with the coolant being golden color. This coloration will cause two serious problems.

The first problem is that the colourimetry of the projector will be incorrect and there will be no way to fix it. For example, this is a blue tube with yellow coolant. The yellow color will have a similar affect as adding color to the glycol in the application of fixing the primary colors. However, since blue is already perfect without correction, the yellow colored glycol will basically add yellow to the blue and pull your blue primary towards white. This will result in under saturation in blue (in this case) and your projector will not properly reproduce any color with a blue component.

The second problem with this is that you can't add color to LC 9" projectors because they have curved C elements. When you add color to the glycol, the light at the center of the image will have to pass through less colored glycol than the portion of the image at the sides of the tube. This will result in serious problems in field uniformity because the center of the image will be brighter (and in this case bluer) than the sides. You can try and correct this with the CMM in the Marquee, but this is not what the CMM is for and it will wind up being over driven. Also, over time the glycol will get more and more yellow so the uniformity will vary.

Here is a photo of the glycol after I drained it.

It should be crystal clear, not at all yellow.

Look into your blue tube and see if there is any coloration. If there is, it is also likely that the red and green also have the same problem. On projectors with a clear C element on the red assembly you will also be able to see the yellow problem. However, if you have colored C elements for red and green, you will most likely not be able to see the yellow coloration. In this case I would recommend just dumping the coolant in all three tubes, clean them out, and refill.

After that you will need to redo gray scale as the primary colors will have changed.

craigr

draganm · Joined: 08 Mar 2006 Posts: 8990 Location: Colorado

His green was the same way, pretty awful. I'm betting it's either 15 year old original Glycol or the original seller was stupid enough ot re-use old glycol when they potted the Red and blue (which BTW were both leaking around the potting)Overall the entire LC assembly on that machine was a total hack-job:(
I'm glad you'll be finalizing it and putting the finishing touches on the set-up Craig

Ben851 · Joined: 13 Sep 2008 Posts: 221 Location: Ottawa, Ontario

That's funny I have zenith pro 841 (it was free) that has the exact same issue... I figured the whole tube had yellowed...

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Craig if you need two more bellows just order one and Ill send you two.

Athanasios

WTS · Joined: 08 Mar 2006 Posts: 1276 Location: Calgary

So what causes it to turn yellow, is it the heat from the tube?

CIR Engineering · Posted: Fri Jan 22, 2010 7:36 pm Post subject:

For those who don't know, this is what a blue tube with good glycol should look like in a 9500LC.

craigr

CIR Engineering · Posted: Fri Jan 22, 2010 7:39 pm Post subject:

CIR Engineering · Posted: Fri Jan 22, 2010 7:41 pm Post subject:

CIR Engineering · Posted: Fri Jan 22, 2010 7:43 pm Post subject:

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Ben851 · Joined: 13 Sep 2008 Posts: 221 Location: Ottawa, Ontario

draganm · Joined: 08 Mar 2006 Posts: 8990 Location: Colorado

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

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

I'm having a bit of a problem with that in my own machine and I retubed it in 2005. Just 5 years later.

The problem started becoming visible just recently with a greenish cast to the perimeter of the screen when showing a pure blue field.

As the glycol is "deepest" at the perimeter, this makes perfect sense, optically speaking.

One issue with the Marquee LC assembly is that the glycol is slightly corrosive to aluminum, and the chamber is aluminum, but it's
anodized. However it's not perfectly protected against glycol attack.

I can take a clean piece of aluminum, close it up in a jar of glycol, and observe it slowly start to corrode over a period of time.

I BELIEVE that an optimal solution would be to obtain some black industrial epoxy paint and paint all inner aluminum surfaces that will
be touching glycol. For obvious reasons this would best done when the CRT is completely out of the housing and the bellows is not
attached, either.

Several gun finishes may also be appropriate: KG Guncote, Cerrocote, or Duracoat.

If anyone has stripped LC chambers lying around, they would be ideal for making this experiment a reality.

Since I'll have to go in there anyway, soon, I'll be removing the old bellows, cleaning everything, mask off the CRT, apply epoxy
paint, install new bellows, and see how that holds up for the long term with fresh glycol.

CJ

**Curt Palme** · Posted: Fri Jan 22, 2010 11:57 pm Post subject:

Consumer Hitachi RP tubes are also known to do this.

secstate · Joined: 20 Mar 2006 Posts: 720

I got some NOS Ampro Retro P16s off of GL a few years ago. Still new in the box, never used, probably about 6-7 years old at the time and while not quite as bad as this the glycol was quite yellow. So it happens even if the CRT is not being used.

**AnalogRocks** · Posted: Sat Jan 23, 2010 4:32 pm Post subject:

Holly apple juice bat man!

CIR Engineering · Posted: Sat Jan 23, 2010 8:31 pm Post subject:

CIR Engineering · Posted: Sat Jan 23, 2010 8:32 pm Post subject:

CIR Engineering · Posted: Sat Jan 23, 2010 8:33 pm Post subject: