|
|
Post by gjaky on Jan 13, 2018 15:20:12 GMT -5
It's about time to replace the tubes in my 9500 (= it may happen in this year).
I have a good set of tubes those need rework with the chambers. Glycol is yellow, the housing has been eaten away at some points, there is fungus inside, the bellows are sweating, everything you can imagine... In theory I have everything what is needed to refurbish them, I even have a set of blank tube housings. But I have zero machining capability here (no big clamps, no wood blocks, no nothing) so I am not sure I could extract the good tubes from the housings without damaging them.
Instead I'd try to repair the old housings.
My plan is to paint the frame around the tubes to black, so the aluminium would not be exposed to the glycol anymore.
Old threads suggested to use epoxy paints, but those are rather hard to come by (here at least). So what about the simple acrylic paints? The C-element itself is made from acryl so it could not be that bad... I have a chemist colleague who also does not see any reason why it should not work.
While at it I would attempt to paint the surface of the tube as well (obviously, part of it), as I would only use the machine with 16:9 raster, so a good portion of the tube could be masked out, with the hope of better ANSI contrast.
Any thoughts?
|
|
|
|
Post by stridsvognen on Jan 13, 2018 16:03:59 GMT -5
I did paint 2 chambers with polyester/ topcoat, its a 2 component paint used for boats/ fiberglass stuff, its quite easy to find.
I did paint the chambers and change the bellows, but 1 month later my glycol was yellow again, and i spend a lot of time claning that stuff.. So ill have to try a different glycol next time.
|
|
|
|
Post by gjaky on Jan 13, 2018 17:37:49 GMT -5
They say the rubber washer is the main culprit for yellowing, and indeed I also see more yellow traces trails around the filling hole, in the glycol.
|
|
|
|
Post by stridsvognen on Jan 14, 2018 8:54:14 GMT -5
i had good washers from a 2011 chamber, so i very much doubt that was the issue, never seen any of the later chambers having any issues, i think the problem i see is more likely the bellows.
|
|
|
|
Post by Casethecorvetteman on Jan 17, 2018 4:32:04 GMT -5
Use propylene glycol, you shouldnt have any dramas with it eating anything
|
|
|
|
Post by thelasttubewarrior on Jan 17, 2018 9:13:45 GMT -5
Hi, guys. You may know me from Curt's under a different name.
I've got plenty of Marquee hardware, bellows, stainless screws, clamps...and I can help.
I've found that even epoxy painting the aluminum tube frame is no guarantee against formation of white clouds.
I'm currently testing a powder coated assembly and it's going to take a while to verify its protective ability for the aluminum and
for resistance to attack by glycol without yellowing. So far the results have been good.
It should be very easy to obtain three large C clamps and a thick wood block for tube removal from the housing.
As an experiment, I tried to use this method to pop a worn tube out of the Marquee housing WITHOUT even bothering to drill or dig out any of the potting silicone, just to see if it could be done.
It worked. It took a lot of clamp force but when the wood pressure block is in contact with the entire available tube face, you are pushing against a VERY strong tube face. And to make things better, when the tube came out it dragged nearly all the silicone out with it as well. (Original VDC potting job, that may not work so well with aftermarket silicone potting as nobody else uses the Shin-Etsu KE1800 silicone that VDC does.)
For a salvaged tube I would recommend cutting out as much silicone as you can. For a tool to do it, get yourself a paint scraper and sharpen that blade. It works as good as anything to cut the silicone without making you work too hard.
I would also suggest that the best finish for the LC chamber aluminum in contact with the glycol would be to have the plates refinished in the original hardcoat aluminum anodizing. It lasts for a very long time before contaminated acidic glycol can eat through it.
|
|
|
|
Post by tschaeikaei on Jan 17, 2018 19:47:18 GMT -5
Hey, nice to see that it is going on in the CRT section.
I would not cut out a tube if not absolutely needed. Tried it once, destroyed the tube.
I think your idea to paint the housings is the best.
It should be obvious that thoroughly cleaning the housings is very important.
If clean, they can be painted with matte black color, i did use the cheapest standard spray paint i had laying around.
That was 2 years ago.
No problems so far.
If you want to make sure that it will last forever.... i'd propose you brush the housing with any epoxy (glue or whatever)
and then (spray-)paint it afterwards. That seals the aluminium and you're free to choose any color of epoxy that's available.
It may be good to use stainless screws to prevent from further corrosion. In my opinion, rusting screws contribute a fair amount
of yellow / brown to the glycol while aging.
Additional black (engine seal) silicone as a thin layer on the new bellows helps sealing the thing.
Regards, Julian
|
|
|
|
Post by gjaky on Jan 18, 2018 2:10:24 GMT -5
Hey, nice to see that it is going on in the CRT section. I would not cut out a tube if not absolutely needed. Tried it once, destroyed the tube. I think your idea to paint the housings is the best. It should be obvious that thoroughly cleaning the housings is very important. If clean, they can be painted with matte black color, i did use the cheapest standard spray paint i had laying around. That was 2 years ago. No problems so far. If you want to make sure that it will last forever.... i'd propose you brush the housing with any epoxy (glue or whatever) and then (spray-)paint it afterwards. That seals the aluminium and you're free to choose any color of epoxy that's available. It may be good to use stainless screws to prevent from further corrosion. In my opinion, rusting screws contribute a fair amount of yellow / brown to the glycol while aging. Additional black (engine seal) silicone as a thin layer on the new bellows helps sealing the thing. Regards, Julian Thanks Julian for the insights! In fact my housings are not that bad, but one can spot the black stains on the housing that is clearly the sign of the corrosion, but no fungus in the glycol yet. I have new bellows and stainless fill screws for the refurbishment, as said I even have a blank set of 2010 tube frames, but there are some scratches on their grey coating, so much the aluminium is visible underneath, so I am not completely sure if those would be of help without further treatment, then why bother?  |
|
|
|
Post by thelasttubewarrior on Jan 18, 2018 11:04:59 GMT -5
No, don't silicone the bellows sealing surface. It's totally unnecessary. As long as you have "new style" VDC bellows, or Nash's bellows, and a late model plastic clamp ring (better pressure distribution) and stainless hardware, you can get a perfect and reliable seal and the amount of torque required on the screws is so little that the proper way to tighten the bellows clamping screws is to obtain a hex driver bit in the appropriate size and hold the bit in your fingers and tighten the screw to finger tight only.
I have a torque screwdriver and its lowest setting is 3 inch-pounds. And THAT is too much for a bellows screw. I'd say ONE inch-pound of torque is plenty.
I just don't know how you can destroy a tube by trying to remove it from the housing unless you're prying against the glass or using a hammer.
Use the C clamp and block method. Use big C clamps and the corner of a sturdy table. Increase pressure on the clamps in stages.
Digging out silicone before the clamps are used can be helpful. Especially if it's not VDC's silicone job. For that job, CR Lawrence sells a pipe knife and long blades
which are incredibly useful for tube work. This is a razor utility knife that has great reach and you can put some power behind it.
I've removed and replaced literally hundreds of tubes from Marquee housings and never broke one. You can do it, too.
Once the tube is out, remove the four screws that hold the back of the housing to the front plate and then you will need to pry the two pieces apart as they are siliconed.
This takes a fair amount of effort. I use cheap wood chisels which WILL get damaged but the thin edge gets in between the surfaces and allows them to be levered open.
Clean up the three liberated plates and take them to your local anodizer for a HARDCOAT anodize treatment. Specify hardcoat and not regular anodizing. If your local shop can't do hardcoat, Google will help you find one that can.
That'll last you 10 years or more.
|
|
|
|
Post by tschaeikaei on Feb 6, 2018 21:12:19 GMT -5
Well, i think i made a mistake here. After using my Marquees a fair amount in the last months, i noticed halos on black background around bright menus. Looking into the lenses confirmes: the glycol is cloudy again. Shame on me for telling you it was good. Now looking for a vendor of "ice clear AF" (or similar) in Germany. Are there any threads about coolants i did miss? Ice clear AF
All about Glycol CRT coolant and where to buy
Barco 808LC Glycol Replacement
Ice clear product page
Experiments with glycols and similar stuffThe refractive index of PMMA (=acrylic) is 1,492, monoethyleneglycol's 1,4318, glycerine's 1,4745. I do not know if c-elements are made of PMMA, that's a guess. One could also tend to use propyleneglycol, but according to Wikipedia, it is highly hydrophilic. I donot know if water would diffuse through the bellows and into the propylene glycol, but in the case of monoethyleneglycol, it does. If anyone does have the possibility of using a refractometer with a C-element, i'd be thankful. Regards, Julian |
|
|
|
Post by km987654 on Feb 7, 2018 0:33:24 GMT -5
Well, i think i made a mistake here. After using my Marquees a fair amount in the last months, i noticed halos on black background around bright menus. Looking into the lenses confirmes: the glycol is cloudy again. Shame on me for telling you it was good. Now looking for a vendor of "ice clear AF" (or similar) in Germany. Are there any threads about coolants i did miss? Ice clear AF
All about Glycol CRT coolant and where to buy
Barco 808LC Glycol Replacement
Ice clear product page
Experiments with glycols and similar stuffThe refractive index of PMMA (=acrylic) is 1,492, monoethyleneglycol's 1,4318, glycerine's 1,4745. I do not know if c-elements are made of PMMA, that's a guess. One could also tend to use propyleneglycol, but according to Wikipedia, it is highly hydrophilic. I donot know if water would diffuse through the bellows and into the propylene glycol, but in the case of monoethyleneglycol, it does. If anyone does have the possibility of using a refractometer with a C-element, i'd be thankful. Regards, Julian Look Here for some Ice Clear information www.curtpalme.com/forum/viewtopic.php?t=37673&highlight=glycolOn reading that thread I see you have already been there  |
|
|
|
Post by gjaky on Feb 7, 2018 4:45:20 GMT -5
Well, i think i made a mistake here. After using my Marquees a fair amount in the last months, i noticed halos on black background around bright menus. Looking into the lenses confirmes: the glycol is cloudy again. Shame on me for telling you it was good. Now looking for a vendor of "ice clear AF" (or similar) in Germany. Are there any threads about coolants i did miss? Ice clear AF
All about Glycol CRT coolant and where to buy
Barco 808LC Glycol Replacement
Ice clear product page
Experiments with glycols and similar stuffThe refractive index of PMMA (=acrylic) is 1,492, monoethyleneglycol's 1,4318, glycerine's 1,4745. I do not know if c-elements are made of PMMA, that's a guess. One could also tend to use propyleneglycol, but according to Wikipedia, it is highly hydrophilic. I donot know if water would diffuse through the bellows and into the propylene glycol, but in the case of monoethyleneglycol, it does. If anyone does have the possibility of using a refractometer with a C-element, i'd be thankful. Regards, Julian Dammit! The SDS of the Ice Clear AF is suggesting it is in fact 40-60% glycerol and the rest is water, the only trick is the added anti corrosion agent. The Ice Clear PGX is the same but without the anti corrosion agent. I am not a chemist but we have one at the company where I work, and he told me that these anti corrosion agents are usually simply added ions to prevent reacting with the different metals, now we only have to take care about aluminium. Glycerol is also highly hygroscopic, I guess this mechanism is strongly related to the "anti-freeze" behaviour of these solutions. The new bellows (either Nashou's or VDC) should stop diffusing water through them, so that should not be a problem.  |
|
|
|
Post by tschaeikaei on Feb 7, 2018 9:58:50 GMT -5
Hey guys,
Gjaki: Yeah, i've seen that. 40% water, 'bout 4% anti-corrosion agent + some glycerol.
I think the waters job is improving heat capacity and lowering the viscosity.
Glycerol is rather thick, i use it in my electronic cigarette's liquid.
It has the about right refractive index of 1,4746 (closer to 1,49 of PMMA than any of the other substances)
but... it is highly viscous and i do not have numbers about it's heat transfer properties.
When glycerol and propylene glycol is mixed (you do that when mixing electronic cigarette's liquid), it makes "schlieren"
(which seems the same word in English as in German). The schlieren disappear when thoroughly mixing, but I'm not to sure about it's optical properties.
Will do some experiments...
I hope you haven't refilled your tubes with monoethyleneglycol so far! Or if you did, you really painted the housings with a thick layer
of epoxy. I underestimated that shit. Shame over me.
I think i will take one of the (clear) c-elements i have here to the university in the next days and ask about a refractometer and someone who can use it.
Maybe I'm lucky and we'll finally get a number of that c-element refractive index.
Regards, Julian
|
|
|
|
Post by gjaky on Feb 7, 2018 11:12:30 GMT -5
No, my tubes are still sitting on the shelf untouched...
Using glycerol-water mixture seems to be a good overall solution, since it does not seem too aggressive either.
|
|
|
|
Post by tschaeikaei on Feb 7, 2018 20:51:44 GMT -5
No, not aggressive, cheap and if there's already water in the mixture, it shouldn't be too hygroscopic anymore.
...I hope so.
Propyleneglycol (PG) is also clear to the eye. It has a smaller refractive index, but is much less viscous.
But the most important point is still not not confirmed. I don't know about the translucence of this stuff.
It let's visible light easily pass through. But since there curves and data on the internet about the
translucence and refractive index vs. wavelength (of other substances)... i'd be glad to find such data for PG
and vegetable glycerol (VG).
You can get either of these two in vape- shops for about 11€/L in Germany, maybe similar in your place.
But: If you buy PGor VG in a vape shop, it comes in brown plastic bottles (-->UV-protection)
and they print a best before-date on it. About 2 years...
Best solution would be to find out what kind of anti-corrosion- additive or stabilizer
to extend the life of the stuff.
My next goal is to test the c-element with a refractometer and going with data instead of guessing and trying.
Any plans for your tubes? What are you planning to fill the housings with?
Regards, Julian
|
|
