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Discussion Starter · #1 ·
Touched upon recently was the need for LC chambers to be full, even for very short periods, to prevent phosphor wear/burn. In that thread, it was very briefly speculated that keeping the glycol cooler might _extend_ tube life.

Given how easy it'd be to mod an LC tube for greater heat transfer, I think it bears discussion.


I've laid my hands upon my first sets of LC tubes (from my recently acquired RetroData 801 PJs) and the first thought I had was "convection cooling" when I saw the loop of hose running around the tube bell.


Besides providing a short circuit path for HV, what's to prevent us from changing a length of the tubing to copper of black tin?

Just as importantly, what quantative test can be applied to whether tube life is improved?

(IIRC, black tin won't oxidize and pollute the fluid, which is why it's used in beverage systems. Fifteen year old memories here, probably flawed.)


[RANDOM, IGNORANT SPECULATION] I'm thinking of CMJ's frankenyolks, which may cause greater wear given a spot size markedly smaller than the original when the phosphor was laid down.[/RANDOM, IGNORANT SPECULATION]
 

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First, the reason the retro uses the long hose are that the tube faces up when running. In a normal PJ the coolant has chamber on top of the tube to catch the air bubbles, if you face the tube up the air bubbles will be present on the face of the CRT. So this is why the retro always has the tubes, this is to catch the air bubbles.


Second cooling the CRT is great, BUT the tube does need to be warm to operate properly. This is why a warm-up period is required before the picture looks perfect. If you converged a tube cold then let it run hot the converging will be off. So super cooling the CRT is not needed or really desired. Maintaining a consistent temperature on the CRT is preferred, knowing the actual designed temp would be nice this way you know what is too hot. Adding special features or turning up the brightness may require additional cooling. Unfortunately you cannot just cool the tube to a super low temp, you need to create a controller to kick in additional fans or cooling pumps only when the tube is above the normal design spec.


Here is another thought with your 07MPA tubes. The front chamber will allow HD-145 or HD-144 lenses to be fitted directly to it. Everyone wants color Filtered lenses on there PJ you can do it without adaptors with the 07MPA. The only question is what the focus range will be with the LC housing designed for short projection and HD-144 lenses made for long throws? I have a set but haven’t tried it yet, just think color corrected and filtered plus liquid coupled lenses on a 801, all the 808 users would be jealous of you.


Pat
 

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Discussion Starter · #3 ·
Hmmm put the LCs in my BG801 FP . . . that's a mod I had considred but decided I could not do it with GT114 and GT117 lenses. I'll have to try it with my burned MPAs and 42000 hour BG801 chassis (if I can find lenses.)

Good point on the air bubbles, that reason did not even dawn on me.

As for cooling, I has intended to simply replace a portion of the hose with metal so as to conduct away more heat. The problem, as you identified, is we have no quantatative means of determining if there is any benefit, especially in the absence of design specs for the tube/phosphor.
 

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The cooler the phosphor, the higher the light output.

Goal is room temp...

Roland
 

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You can't add AC lenses to LC tubes, there'd be 2 C-elements for a start...it won't focus.
 

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Quote:
Originally Posted by 4101 CRT
First, the reason the retro uses the long hose are that the tube faces up when running. In a normal PJ the coolant has chamber on top of the tube to catch the air bubbles, if you face the tube up the air bubbles will be present on the face of the CRT. So this is why the retro always has the tubes, this is to catch the air bubbles.


Second cooling the CRT is great, BUT the tube does need to be warm to operate properly. This is why a warm-up period is required before the picture looks perfect. If you converged a tube cold then let it run hot the converging will be off. So super cooling the CRT is not needed or really desired. Maintaining a consistent temperature on the CRT is preferred, knowing the actual designed temp would be nice this way you know what is too hot. Adding special features or turning up the brightness may require additional cooling. Unfortunately you cannot just cool the tube to a super low temp, you need to create a controller to kick in additional fans or cooling pumps only when the tube is above the normal design spec.


Here is another thought with your 07MPA tubes. The front chamber will allow HD-145 or HD-144 lenses to be fitted directly to it. Everyone wants color Filtered lenses on there PJ you can do it without adaptors with the 07MPA. The only question is what the focus range will be with the LC housing designed for short projection and HD-144 lenses made for long throws? I have a set but haven’t tried it yet, just think color corrected and filtered plus liquid coupled lenses on a 801, all the 808 users would be jealous of you.


Pat
The "chamber", which is only on "some" tubes and not even all LC tubes, is for expansion and has nothing to do with bubbles.


What projector uses an 07MPA ? I'm familiar with 07MS, 07MP, 07MSP and 07MTS, are 07MPA for some retro unit?
 

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I would suggest attaching a Peltier cooling device to the LC casting, with a thermocouple

on the other side of the casting, and building a circuit to control the Peltier device based on

sensed temperature. A servo loop thermostat.


CJ
 

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Discussion Starter · #8 ·
Quote:
Originally Posted by cmjohnson
I would suggest attaching a Peltier cooling device to the LC casting, with a thermocouple

on the other side of the casting, and building a circuit to control the Peltier device based on

sensed temperature. A servo loop thermostat.


CJ
I can certainly implement a PID loop controller (I've ptobably got ten in a drawer at the office,) but wonder if a pelteir (sp?) junction would be effective (i.e. can it sink and dissipate enough heat?)

I was thinking something completely passive, like an oil cooler off of a motorcycle (if materials are appropriate) but it is the passive part that makes it hard to control and quantify the benefits.

Are there published output/unit temperature curves that we can referance?
 

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A Peltier device as found in many CPU coolers can provide enough cooling to keep an overclocked P4 running icy cool. It can handle keeping an LC assembly at room temp.


CJ
 

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Discussion Starter · #10 ·
Good point. Here's a thought: Couple a microprocessor liquid cooling plate to a pelteir and heatsink, so you will be effectively cooling the glycol directly. This will eventually bring down the temp of the casting, but would have a much more direct (efficient, shorter cool-down time) path to the face of the crt.
 

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I'm not sure I follow.


How would you get the cooling of the glycol directly rather than through the heatsink?


You mean route the glycol through the plate via tubing and a small pump? (I don't have

any experience with microprocessor liquid cooling plates.)


If so, you'd of course have to modify the LC chambers for the coolant fittings.


CJ
 

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Discussion Starter · #12 ·
I'm still assuming that all or most LC assemblies are like those on my RD801: tube comes out of the top of the LC assembly, wraps three times around the neck of the tube, and then goes to the bottom of the LC chamber.

Plumb the glycol through a coldplate from a DIY PC liquid cooling kit, and rather than use the cold plate to carry heat away from a microprocessor, use a peltier to cool the coldplate and thence the glycol.

This site shows a great picture of an active peltier with integral coldplate and host barbs, but the peltier would be upside down (we want to cool the fluid, the typical DIY liquid cooling application warms the fluid.)
http://www.sidewindercomputers.com/swmc7.html
 

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Just get some stainless steel tubing and wrap it around something to make a coil about half the size of the output of one of the projectors cooling fans and connect your tubes to it.

A three or four wrap coil mounted in line with one of the fans should do it. The increased cooling of the fluid outside the LC coupling block should help increase the natural gravity circulation of the coolant.


Chip
 

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The question is:

If you pump the glycol, would you see any schlieren (dict.cc told me that word is the same in English and German) in the picture?

Roland
 

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Schlerien effects would probably not be visible as the wavefront distortions caused would

have to be at the focal plane, which is the tube face. Just as a floating speck of junk in

the glycol is not visible on the screen, neither would be those effects.


Ever done a study on Schlerien optics? It's fascinating stuff.


And there was one type of projector, the oil film light valve projector, that actually uses schlerien optics.


CJ
 

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Have anybody ever tested Retro LC-chamber+C-element with HD8* or HD144*/HD145* lenses?

*Certainly original "C-elements" have to remove from lenses...


I'm going to test it some day, unless somebody can tell it doesn't works. :)
 

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SO, who has done this yet?
 

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Discussion Starter · #18 ·
If I can lay my hands on one or three lenses I can do this with my collection of spares. Being an ignorant noob, however, prevents me from doing an accurate analysis.

Chip, got any HD144 or 145 lenses in your collestion?
 

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For a cheaper test you can also just use the normal lens from any ECP projector is HD-06? darn I forget the number, anyways you don’t need to use HD-145 color filtered just for the focus test, you can find many of the other lenses on Ebay for cheep.


As Mark-A said you may need to remove the first element on the lens or two c-elements will be combined and not work at all.


I still worry about what you guys are saying about cooling the tubes, I agree additional cooling would be beneficial but think too much of a good thing is bad. The process of electrons hitting the screen produces heat and light, much like fire it too produces heat and light. If you take heat away from a fire you effectively put it out and have no light.

A peltier pump can get very cold I would worry that either the light output would be dim if too cold or actually break the tube due to the extreme differences in temperature. Additionally converging wouldn’t be stable.


My next sentence will take all that back by saying a peltier pump and microprocessor controller would be perfect. If you can effectively control the temp and keep it constant yet not too low this may be better than the standard fan cooling. A fan doesn’t change in speed as the temp rises in the tube, extreme output in light will not receive additional cooling. So I’d say do it Dude but do it smart;)


Last for Techman707 the 07MPA or 07MSPA tube is actually just a 07MP with a different housing. It has a LC element and tubes that wrap around the neck filled with glycol. The 07MPA’s also have bolts that fit the smaller lenses found in ECP’s this is what got me thinking about adding color filtered HD-145 to the tubes, 07MPA’s are found in retro’s.
 

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I missed something here. This thread went from trying to figure a way to cool the existing tubes better to air cooling/coupling which will cook the tubes for sure. An air coupled tube still has a plate of glass in front of the tube with coolant behind it. The other problem is that you can't just remove the c-element and mount a standard lens. The distance from the tube face to the first element would be too great and give the appearance of zooming out(larger throw ratio).


Chip
 
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