CurtPalme.com Home Theater Forum

winny

Perhaps an introduction would be appropriate first. My name is Andreas and I'm an 29 year old electronic engineer specializing in analog and digital power supplies living in Sweden. I'm completely new to CRTs so when it comes to new TLA's, part numbers and CRT jargon, I don't have a clue what you are taking about, yet. I do however understand the theory of operation and I would have no problem oscilloscopeing, reading the schematics and repair any part of the electronics. Haven't played with high voltage but I have (accidentally) taken 230 VAC from my left hand to my right so I'm not a complete virgin either.

Bought a Barco 1209/2 which had two known problems, no red output and glycol leak. Apart from that it was running fine and I watched it in operation before we took it down from the seller and packed it up for the long journey home.

I opened it up yesterday and found a lot of glycol inside. Messy stuff but the PCBs seem to have been spared from it. From what I could tell, there was no glycol inside the tube of the red tube, but it was very hazy so difficult to tell. The blue and green was filled almost all the way on the other hand. I apologize for the focus. Sony telephone = very high resolution camera wasted by useless focus. Thumbs Down

As a total CRT newbie, I need to ask some dumb questions.

1. Does glycol leak cause immediate tube failure at turn on? The red tube was working six months earlier but the seller said he hadn't used it much/at all since. He just powered it up to take a picture of the (lack of) ware for me. Could it have started to leak over time and when he turned it on again before the sell it failed?
I was under the impression that the glycol's main function was to act optical medium to stop haloing. With about 550 W input to the projector and lots of losses on the way, I don't see more than 150 W hitting the tube face and several kg of glass to absorb the heat so even if the glycol is there for cooling, the peak temperature would not rise that quick.

2. If glycol leak over time, wouldn't this be visible as picture distortion?

3. What else could cause the red channel to stop functioning? Is there a way to troubleshoot? Any on-board diagnostics?

4. I read about colored glycol to improve the color rendering and this is highly appealing to me. As a light-nut, I usually try to play "guess the light source" with my friends which includes discriminating pink skin tones being rendered slightly different under different batches of LEDs, or telling metal-halide from fluorescent and telling 2700K from 3000K by no other aids than just built in "absolute pitch". This will quickly reduce the number of people who want to hang out with you if anyone is interested to reduce their social circle Wink

. If I need to fix a new tube and refill the glycol, can it be retrofired with colored glycol?

5. Suppose the red tube is broken, what can it be replaced with? What options do I have if the neck boards are modified (looks easy to do)?

Decibel · Joined: 31 May 2007 Posts: 904 Location: Roma - Italia

First of all remove the convergence tray (loosen two screws show in my photo an pull the tray) and check if glycol has go in this tray.

winny · Posted: Sat Oct 12, 2013 9:08 pm Post subject:

Decibel · Joined: 31 May 2007 Posts: 904 Location: Roma - Italia

The glycol MUST fill the chamber of the tube.
Check the point of leak and repair.
For find failure of the red tube you can swap the neckboard (black square element at the end of the tube) with the green or blue one.

**Curt Palme** · Posted: Sun Oct 13, 2013 2:08 am Post subject:

Barco 1209 had poor LC housing designs. What happens over time is water gets absorbed into the housing and causes extreme pressure within the LC chamber. Also, if the set was moved around a lot in the past, the pressure causes the silicone seal between the tube and the housing to crack, causing leaks.

Take all three tubes out. Take the tubes outside, and pull off the plastic hoses. Be careful, if there's a lot of pressure in the hoses, the glycol can shoot up 1 metre. ONce it shot right into my face! it's poisonous if you swallow it, but it will not hurt your eyes.

Leave some air bubbles in the hoses to prevent pressure. Chances are the G and B tubes will be fine, but if you see a crack around the red tube in the silicone, then drain all the glycol, and cut the old silicone out around the crack, right to the glass tube and to the outside metal housing. Reseal with new silicone and let it seal for a week. Fill the tube with water, check for leaks overnight, and if there are no leaks, then fill with glycol.

Failure to do exactly the above will result in more leaks.

The red tube almost guaranteed will be fine. the black video amp on the end of the tube is probably bad. I've got lots of spares if you need one. A quick way to check is to swap the video cables between the green and red tubes via the RCA connector at the top of the video amps. You'll find out if the problem is the video feed from the video switching PC board, or whether it's the video amp on the back of the tube.

km987654 · Posted: Sun Oct 13, 2013 2:31 am Post subject:

Barco did a terrible job sealing those tubes in th LC housing and the silicon sealant has a limited life. If you're up to it you should remove the tubes from the housings and reseal with new silicon a big job but should reduce the risk of a leak. Glycol is horrible stuff and will ruin the electronics if it comes in contact.

winny · Posted: Mon Oct 14, 2013 9:22 pm Post subject:

Decibel · Joined: 31 May 2007 Posts: 904 Location: Roma - Italia

Each lens has 4 screws around the base.
Where is the problem to remove them?

winny · Posted: Mon Oct 14, 2013 10:03 pm Post subject:

Screws where no problem, but the lens was still stuck without screws.

Decibel · Joined: 31 May 2007 Posts: 904 Location: Roma - Italia

In my BG1209s there are 4 screws around each lenses (hd120, the same of your 1209/2).
Then there are other 4 screws that fix the frontal of the tube at frontal panel.
Are you sure that you loosen right screws?

winny · Posted: Mon Oct 14, 2013 10:20 pm Post subject:

In that case, no. Can you show with a picture?

Decibel · Joined: 31 May 2007 Posts: 904 Location: Roma - Italia

winny · Posted: Tue Oct 15, 2013 7:01 am Post subject:

Decibel · Joined: 31 May 2007 Posts: 904 Location: Roma - Italia

Perhaps I do not understand due my different language, sorry Neutral

You must REMOVE the four screws for each lense.
The lenses are very heavy and will drop it in your hands, be careful.
I never start tubes without glycol, I do not know what could happen.

Maybe at your own risk you can do it for a few seconds and check if it work.

Decibel · Joined: 31 May 2007 Posts: 904 Location: Roma - Italia

The screw that show in your picture, perhaps fix the tube, not lense.

winny · Posted: Tue Oct 15, 2013 10:20 am Post subject:

winny · Posted: Tue Oct 29, 2013 10:17 pm Post subject:

Result!

I swaped the RCA cable between the red and blue tube and the red lit up fine while the problem moved to the blue.

How to proceed from here?

**Curt Palme** · Posted: Tue Oct 29, 2013 10:21 pm Post subject:

your issue most likely is the RGB switcher board or quad decoder. I can probably sell you tested working ones for less than you will spend troubleshooting them.

One last thing, in case I missed it above: Does the internal test pattern work on the red tube, with the red video wire connected to the red video amp?

winny · Posted: Tue Oct 29, 2013 10:31 pm Post subject:

It does not with red wire connected to red tube but it does with blue wire connected to red tube, but it's quite blurry. My guess due to missing glycol.

Like how much?

**Curt Palme** · Posted: Tue Oct 29, 2013 11:54 pm Post subject:

Yes, don't run the set without glycol, or at least turn on the red tube. you'll burn the phosphor within minutes.
email me at curtpalme at shaw.ca and I can let you know pricing. I've got glycol as well.