CurtPalme.com Home Theater Forum

Melifluonze · Posted: Sun Nov 09, 2014 3:14 am Post subject: Reworking a tube

I have a 9" LC green tube that's been sitting for a bit. It has been leaking. I decided to use it in the stack because I see no raster in the surface of the phosphor at all. I cut off the bellows and removed the very glued in green C element, and a few things came up...

1. I put a hairline scratch or two in the C element as I was cleaning off the extra silicone. They're off to the side abou 2/3 in on the sphere. How visible will a light scratch be, considering the phosphor is the focal point? You can zoom the picture below and see them...

2. I've got some pitting. I poked at it with a knife and found that it's surprisingly deep! Is there a way to stop it, or is there some kind of prep I should do? See the pic below. Or do you just refill the glycol all the time?

3. The tube has a G2 of 75-76, so it's been left on with but no picture. I don't think it's worth cutting out of the LC chamber to mount it into another cleaner LC chamber... Would you agree?

- M

km987654 · Posted: Sun Nov 09, 2014 4:52 am Post subject:

Glycol certainly eats LC tanks when metal is exposed. I have had great results by using a flat finish etching black paint to cover exposed metal.

CasetheCorvetteman · Joined: 09 Nov 2008 Posts: 6326 Location: Australia

The scratches and pits probably wont make a difference to the image that you will see, so its not worth worrying about.

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

If you don't treat the exposed aluminum and pits the glycol will get contaminated.

Use Epoxy paint or if you can find some one to anodize them let epoxy paint cure at least one week
or you'll be removing them and doing it again a few months.

km987654 · Posted: Tue Nov 11, 2014 8:16 pm Post subject:

Yes you need to fix this or your glycol will become cloudy apart from the fact that your LC tanks are slowly disintergrating.

CasetheCorvetteman · Joined: 09 Nov 2008 Posts: 6326 Location: Australia

I never saw that second pic til now, that isnt looking healthy at all...

Melifluonze · Posted: Wed Nov 12, 2014 1:47 pm Post subject:

I used Rustoleum Etching Primer followed by automotive matte black on the non-sealing areas after scraping the oxidized/etched gunk out of the holes. I am NOT saying this is a good combination... I think I actually expect it to fail. I might need to go and get some professional etching primer and aluminum paint. There's some you use for marine applications that etches off all the oxide with a wash, then has an etching primer followed by some kind of 2 part activated paint. But... that's just nuts!

I'll give it a try... I'm a "professional" at re-assembling the darn thing now, at least in my own mind... That C element is HELL to install! The bellows ring keeps pressing back out of the front plate when you install the C element, which then gets silicone everywhere, resulting in a complete tear-down, clean up, and rebuild!

I'd love to hear how other people do this...

1. I have no freakin' idea what size the hex screws are for the C Element ring, and the bellows assembly. I ended up having to use a Torx 20 for the C element ring (and lens mount screws) and a T15 (which really didn't fit) for the bellows assembly. I'd very much like to know the secret hex size and where to get it!

2. Undid the front hinge screws on top and bottom and CUT the bellows out because I don't have the tool to get in between the plates. Not cool. Need to watch out for the C element when you do this...

3. Cleaned up and prepped plates etc.

4. Assembled the new bellows to the back plate/tube face with a thin bead of silicone. Screws tightened to the point where the metal frame started squishing the bellows edge.

5. Assembled the front plate to the front of the bellows (inserting the ring around the flange) where the C element goes.

6. Ran a light bead of silicone around the edge of the C element ring

7. Placed the tube between my legs, neck down, so the face was level, spread the ring one more time, wet the inside edge of the ring gasket and gently dropped in the C element.

8. Placed the C element ring on top and slowly tightened the 4 hex bolts.

9. Wait 24 hours for the silicone to cure and fill with glycol.

ANY hints would be appreciated!

Melifluonze · Posted: Wed Nov 12, 2014 2:00 pm Post subject:

By the way, I also read the advanced procedures...

A couple comments... There's no way I could have removed the C element without pushing it out from inside the tube (pushing down on it when the front plate is off the tube). It is an INTERFERENCE FIT, and it is glued in! How on earth does anyone get these things out just by prying with fingers!? I think that's sheer luck! You'd have to scratch an edge into it with a screw driver and then try your luck at prying it out without breaking the edge!

Secondly, the bellows on the tubes I worked on (which must be old) are completely glued onto the screen face plate, or the rubber has bonded to the face plate. There's no removing them without ripping them, or leaving rubber behind as far as I can see.

And I could not get any sized allen wrench to go into the screw holes. I'm thinking this may be because they were corroded, but there wasn't even a size that was close in either metric or inch!!!

So, yes... I had to cut the thing apart carefully and then take the front, place it face down, and push the C element HARD with a microfiber cloth on the back (to protect it). The element then lets go with a bang (I was leaning on it with all of my weight).

Bottom line... the advanced procedures are great if you have a recent tube that nobody messed with, but they are not applicable to tubes that have been glued, or tubes that have been assembled for decade(s). My bellows were weeping baldy, so I just cut them to get the job done...

- M

jbmeyer13 · Joined: 03 Dec 2010 Posts: 1135

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

Gordon, Use VHT Epoxy Paint from an Auto supply store like Advanced or Autozone. I think both have it.

http://www.autozone.com/paint-and-body/paint-spray-can-and-touch-up/vht-paints-gloss-black-all-weather-epoxy-paint/465690_0_0/

I know they have a satin finish what I used but forgot where I got it from, but it was local.

Nashou

Melifluonze · Posted: Wed Nov 12, 2014 6:06 pm Post subject:

@ jbmeyer... A credit card to have Curt remove it for you, and four letter words due to the cost... Shocked

I must have encountered 5 difficult tubes so far. There's no negotiating these bad boys out without BFI... (Brute Force and Ignorance) I'll try again though. Every single one I did was glued in!

Nash, thanks for the paint type. I'll go grab some.

- M

jbmeyer13 · Joined: 03 Dec 2010 Posts: 1135

redfox001 · Joined: 16 Mar 2009 Posts: 2257 Location: The Netherlands

There was a very good tip on the advanced procedures to find a spot where the c-element comes free easily. I had luck on the third side I tried. Than with a small screwdriver you can pull and make the little hole bigger.

Melifluonze · Posted: Wed Nov 12, 2014 11:04 pm Post subject:

Yeah, I know... I'm hoping my newer ones are easier

Melifluonze · Posted: Sat Nov 15, 2014 6:36 am Post subject:

I took one of the more recent ones apart... WOW! Sooo easy!

I agree... the older tubes are hell!!!