Help - Image pulsating and shaking in sync with click/static noise? - AVS Forum
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post #1 of 14 Old 11-20-2008, 03:12 PM - Thread Starter
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Hi guys,

I have a Barco 708. I haven't fired it up for 2-3 weeks. Last night I started to tinker with geometry when I noticed a weird static / clicking sound coming from somewhere behind the blue tube. I then noticed that the rasters on all 3 tubes were starting to shake and "pulsate" in sync with this noise. It's not loud but it sounds like a mini Tesla experiment (scary). I thought maybe the recent cold temperature might be to blame, so I let it run for a few minutes. No change. I rebooted and got these weird white flashing film-like blotches during startup (no burn, luckily) and the clicking / pulsating continued. I'm worried something's going to blow up if I keep screwing around, so I thought I'd see what you guys thought.

What could be happening and what should I do? Never had a problem with this PJ before, something like 5000 hours on it. I made sure the raster is away from the edge of the tube faces, but it doesn't seem to matter. I'm not very technically savvy but I would like to see if I can diagnose this. Thanks!
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post #2 of 14 Old 11-20-2008, 03:43 PM
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Are you close to me, being in the NW?

This sounds like an HV arcing. If it's a 'tick' rather than a loud 'SNAP', it could be the blue CRT socket on the back of the tube. Here's how to test it.

There's a thick red HV lead going from teh side of the blue tube to the HV splitter. Disconnect that, and power up. THe blue tube will be dead, but I have a feeling you'll still hear the ticking sound, and the R and G tubes will still pulse.

If so, then follow the thinner red wire going from the blue CRT socket to the focus controls on the side of hte red tube, and disconnect the red wire for the blue tube there. (rubber boot pulls back, the single metal pin will pull out of the focus block).

That will now disconnect the blue tube completely from the set. (leave the thick red HV lead off still). I'll bet the ticking goes away and the R and G tubes are stable.

If so, then it's a bad blue CRT socket. I've got spares, or might be able to repair yours.

Either post here, or get a hold of me at the below website.

Cheers!

www.curtpalme.com - CRT tech info

www.soundsolutionscanada.com -pro audio website
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post #3 of 14 Old 11-20-2008, 06:17 PM - Thread Starter
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Awesome Curt, thanks for the help. I'm in north Seattle. This is definitely a 'tick' sound. Luckily no huge snaps, it sounds more like morse code. This set has been stable as a rock up until this. I was messing with resolutions and H & V size when it started to really get noticeable. The image swells uneasily as though the 'reception' is bad. I'll try your tips and post my results. I'll definitely get a hold of you if a part turns out to be busted. Thanks again!
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post #4 of 14 Old 11-20-2008, 07:39 PM - Thread Starter
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Hey Curt, I hope these are what you're referring to, but I can't seem to disconnect the one for blue. I pulled and twisted and it's not budging. How do I get it off?



Also, where exactly is the smaller red wire? I see a soldered one on the top of the tube, and then a couple reds coming out of the bottom of the tube wrapped among a lot of other colored wires. Is this the rubber boot wire you're referring to:



Here's my overview:

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post #5 of 14 Old 11-20-2008, 07:51 PM - Thread Starter
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Wait, are you referring to the wires going into the G2 adjustment box? I can't seem to find anything going into the red tube.
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post #6 of 14 Old 11-21-2008, 02:59 AM - Thread Starter
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Final (optimistic?) update for the night:

I pulled the projector from the wall to get full access to the innards. Turns out the noise is coming entirely from the HV splitter! Not sure if this is related to dirty or loose connections, but merely poking or moving the thick wires corresponds to immediate changes in the noise. At certain angles it outright screams. (I figured out how to pull the blue wire off and I located the focus block, but fortunately these don't seem to be problem.)

I actually managed to calm the shaking / pulsating down after I straightened out the cables a little. But the fragility of this and the high voltage source worries me. Should I maybe try to replace the block, or is there some way to make the connections more secure? Or is the problem deeper than this?

I do have a spare parts projector I could use for swapping, although I wouldn't know where to begin. It is fun diagnosing this all anyway, especially now that it looks like I can fix it. What do you think I should do?
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post #7 of 14 Old 11-21-2008, 06:54 AM
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Be carefull around those wires, 10,000 VOLTS !!! A good idea when working on these PJ's is to keep only one hand not near the chasis. keep it away or in your pocket, you dont want a path to ground for any electricity. With the power off look for any pin holes or cracks in the HV leads(thick red wires), you can sometimes see a leak with the PJ on and the lights off, a blue arc. I bet its the Quad splitter, Curt has the HV splitters.

Athanasios
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post #8 of 14 Old 11-21-2008, 07:06 AM
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This will help:

http://www.curtpalme.com/Barco701_Layout1.shtm

The thick red HV leads come out by rotating the plastic collar on the connector to the splitter about 90 degrees CCW, then the leaad should pull out. Yes, sometimes they stick, but if the collar is loose, the wire should pull out.

THe thinner red leads going from the CRT sockets snake up to the focus block/screen controls on the side of the set. One wire then goes from the G2/focus block to the gray block shown in your pictures above.

At this point, I'd take out all of the HV connectors that go to the tubes from the splitters. Leave the red HV lead coming from the HV quadrupler alone. Fire the set up. If the splitter is still ticking, then it's bad.

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post #9 of 14 Old 11-22-2008, 02:45 AM - Thread Starter
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Hey Curt, I pulled the leads as you said. The ticking seems to calm down this way, but there is still a light electric buzzing sound -- although I don't know if this has always been here? It's only audible when the flap is open. Oddly, when I move any object close to the main connector, the buzz gets loud like a theremin even though there is no physical contact. Also, it's when I close the flap that the ticking gets worse, as though the wires don't like being crowded or messed with.

I attached a video clip of all this. The beginning is the ticking sound coming from the front fan hole with the case fully closed. Then I open the projector and filmed the buzzing directly.

http://www.youtube.com/watch?v=9ix_sK0fl8k

What should I do from here? It still projects OK, but after a couple minutes the ticking and pulsating return.

P.S. Hey nashou66, thanks for the tips, I'm freaked by this thing so I'm keeping my distance as much as possible! I did inspect the wires and I couldn't find any holes or cracks. Also, there is no visible arcing or any light while this is happening. Hmm!
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post #10 of 14 Old 11-22-2008, 11:59 AM
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At this point it's pretty much a matter of swapping out the quadrupler and HV splitter. I'm guessing it's the splitter. Can you solder? That thin white wire on the splitter has to be desoldered and soldered onto the new one. I have lots of splitters.

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post #11 of 14 Old 11-22-2008, 06:36 PM
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Quote:
Originally Posted by Curt Palme View Post

At this point it's pretty much a matter of swapping out the quadrupler and HV splitter. I'm guessing it's the splitter. Can you solder? That thin white wire on the splitter has to be desoldered and soldered onto the new one. I have lots of splitters.

Your DA MAN CURT Were would us CRT owners be without YA.....

Cheers....
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post #12 of 14 Old 11-22-2008, 11:21 PM - Thread Starter
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Quote:
Originally Posted by cinema mad View Post

Your DA MAN CURT Were would us CRT owners be without YA.....

Cheers....

No kidding! I probably would have smashed this thing by now without this kind of support.

I'm going to try to swap out the splitter from my other machine and see how it goes. I assume the quadrupler is a more complex matter? If I fail at the DIY I'll get in touch, Curt! Budget has been kind of tight but I already miss having my Barco. I appreciate everything.
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post #13 of 14 Old 11-23-2008, 08:48 AM
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Nope, the quad is usually easier to swap out. Pull out the SMPS, the quad is bolted to the chassis. Disconnect the red wires at the splitter and focus block, and it comes out without needing to solder. I'll bet it's the splitter though.

I just bought 20 BArco 708s for parts, so I have everything in stock X 20..

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post #14 of 14 Old 01-09-2009, 07:59 PM - Thread Starter
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Hey all, sorry for the pathetic delay. We finally got around to the splitter swap and it seems to have worked. (*Crosses fingers.*) So far, we have only watched about a movie and a half, but the image no longer looks like it's going to blow up and there are no more click noises. So I guess that means it was the right part. Thanks to Curt and everyone else for your help and expertise, much appreciated. I hope I don't run into another issue for a good long while. Here's to another year of CRT!
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