CurtPalme.com Home Theater Forum

[mishaux]

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Hey all, I cant seem to find thoughts on this one in the forums:

Last spring at almost exactly this time of year, my green tube started losing its image briefly now and then. It stayed lit, and kept a very low resolution raster, just a few hundred lines tall at about 10% brightness. It stopped doing it by mid summer, so I ignored it.

Last night, it did it again mid movie, and hasn't come back. I tried swapping inputs, reseating all cards and neck board, and letting it cool down overnight and got nothing.

Its startup is a little odd too, the raster image is huge, about 10% bright, and jumps around a little while high voltage is coming up.

When I bring up the menu, I actually get a reverse image. Places where it should be bright are the only places that are actually dimmed. The attached image is not burn, its just the projected image I get.

Im stumped. Neck board maybe? It sure seems like a circuitry problem on whatever should be doing amplification on the beam... but I only roughly know what I am talking about

Any ideas? Stuff I should try? Boards I should order from Curt?

Thanks everyone!

[km987654]

I take it you don't mean upside down when you say inverted but rather bright sections are dim.

If thats the case it sounds like the RGB end stage on that tube. I believe all those RGB amps are the same so you can swap an RGB amp from one of the other colors to test or if you have a spare put that in. If the problem moves then you know that its the RGB amp thats the problem. There are other possibilities but this one is easy to test.

[mishaux]

You got it, bright swapped for dark.

Neck card swapped with red, and the problem stayed on the green tube, no change in behavior at all. Bummer.

Any thoughts on where to go next?

Thank you so much for your help!!

[Curt Palme]

it will be the tube (unlikely), or the RGB switcher board or quad decoder board. I've got both in stock at $50 each plus shipping.

Since it was cutting in and out before it died completely, wiggle around the boards, tap the tube neck and the CRT socket area to see if you can get the green image to turn on and off.

Oh, on a 1209, it can also be a shielded cable that breaks loose on the motherboard, ,on the underside. Once you take the top cover off, the bottom half is held in with 6 bolts through the chassis to the underside. It's a bit of work, as you need to take that bottom cover off, but it can be done with two people, and the set placed on a table.
Barco twisted the RGB input cables 180 degrees on the chassis, and they snap from time to time, causing no video on one tube color. I'd swap the boards first though and risk the $100 before ripping the set apart.

[Curt Palme]

it will be the tube (unlikely), or the RGB switcher board or quad decoder board. I've got both in stock at $50 each plus shipping.

Since it was cutting in and out before it died completely, wiggle around the boards, tap the tube neck and the CRT socket area to see if you can get the green image to turn on and off.

Oh, on a 1209, it can also be a shielded cable that breaks loose on the motherboard, ,on the underside. Once you take the top cover off, the bottom half is held in with 6 bolts through the chassis to the underside. It's a bit of work, as you need to take that bottom cover off, but it can be done with two people, and the set placed on a table.
Barco twisted the RGB input cables 180 degrees on the chassis, and they snap from time to time, causing no video on one tube color. I'd swap the boards first though and risk the $100 before ripping the set apart.

[mishaux]

Ok, wiggling those two boards makes no difference at all, but tapping on the tube causes all kinds of mayhem. I tried tapping on the other tubes as well with no change at all.

Tapping gently on the neck card caused flickering, tapping on the focus coils caused huge flickering and it even settled in to a different sort of failure mode where I could see the vertical flyback line diagonally across the screen.

It seems strange that the tube would generate clean, sharp scan lines with a ghosty reversed image if it had failed, but I really don't know that much about it.

I had all three tubes out two years ago to replace the old yellow glycol they had when I got the set, and put in some colored C elements while I was at it. Maybe I didn't get a cable plugged back in securely?

Thanks again for your help!

[Curt Palme]

Focus has nothing to do with the tube itself, as the electron beam is focused externally by the focus yoke. Sounds like a heater to cathode short, which is not repairable I'm afraid.

a couple of options: Swap tube locations to confirm for sure it's the tube, swap the R and G tube locations temporarily.

I do have a bunch of green LUG tubes I'd sell cheap that have light 16:9 wear on them, for $100 each. Then you'd have to unpot your tube from the LC frame and silicone this one in, or, I do have low wear 1209s sets (which overall are a newer and better set) for $800 plus shipping. You'd save some on shipping if I sent it without lenses, and you transfer yours over. Your 1209 then becomes a parts set, as most of the modules will interchange.

If it is the tube, and if it was me, I'd upgrade to the 1209s. You'll see a noticeable difference in overall focusing/resolution.

[Curt Palme]

Focus has nothing to do with the tube itself, as the electron beam is focused externally by the focus yoke. Sounds like a heater to cathode short, which is not repairable I'm afraid.

a couple of options: Swap tube locations to confirm for sure it's the tube, swap the R and G tube locations temporarily.

I do have a bunch of green LUG tubes I'd sell cheap that have light 16:9 wear on them, for $100 each. Then you'd have to unpot your tube from the LC frame and silicone this one in, or, I do have low wear 1209s sets (which overall are a newer and better set) for $800 plus shipping. You'd save some on shipping if I sent it without lenses, and you transfer yours over. Your 1209 then becomes a parts set, as most of the modules will interchange.

If it is the tube, and if it was me, I'd upgrade to the 1209s. You'll see a noticeable difference in overall focusing/resolution.

[CasetheCorvetteman]

If it was me, and you were to upgrade, id make it more worthwhile than another bloody Barco!!!

[mishaux]

Bummer!! I've actually got a spare green that I picked up from you a couple of years ago when you were blowing some out. I'll get them swapped out and see what happens.

An upgrade is pretty tempting too, this set I have has totally clean tubes in it (aside from this possible short), but the chassis is coming up on 16k hours. Its starting to feel like I am on borrowed time. Sounds like CasetheCorvetteman thinks I've been on borrowed time from the first minute

Thanks again for the help!!

[CasetheCorvetteman]

Not quite, but if i was throwing up another Barco id be stepping up to a Cine 9 or at least a 909, although ive had a few issues with mine lately, its fine again now...

[mishaux]

Ok folks, I swapped the green tube for a spare I had around. That was a hell of a chore.

There is good news and bad news.

The good news is that there doesn't seem to be any mechanical problems anymore. Tapping on stuff no longer causes flickering or diagonal flyback lines to flutter in and out.

The bad news is that I still only get an oddly inverted image. dark areas are brighter, and areas that should be lit up are black. See the image above in this thread.

The other bad news is that I found that the big capacitor on the h output board has been drooling all over. Maybe thats related?

I swapped the phono jack which I assume caries the video signal between the red and green tubes and the problem went with it, so its somewhere in the signal chain before the neck card.

Any thoughts? Is that leaking capacitor a possible culprit? It seems like the intermittent heater-cathode short and this faint inverted image thing happened at exactly the same time. Any chance the short damaged something further back on the signal chain?

Curt, you mentioned kinked RGB cables, is that wire with the phono jack the cable you are talking about? Maybe the green one broke loose? Or just the shielding did or something?

[Curt Palme]

6 months to change a tube? (don't feel bad, I just fixed an amp last night that I had sitting on the shelf.. with parts on top of it.. for 18 months. )

The cap on the H board is a separate problem.. I can either sell you a new cap, or a whole board, I've got lots of both.

your negative video problem is indeed coming through the RCA cable, so either your quad decoder or RGB switcher board is bad:


http://www.curtpalme.com/Barco1208_Layout2.shtm

What I need is the 762XXX part numbers off the boards, that should be stamped on a white sticker somewhere. THe numbers on the top white sticker are the serial numbers, which don't help.

You'll also need to adjust your G2 settings for the new tube, but we'll do that after we get the image back. Email me those part numbers at curtpalme@shaw.ca

Thanks!

[Curt Palme]

6 months to change a tube? (don't feel bad, I just fixed an amp last night that I had sitting on the shelf.. with parts on top of it.. for 18 months. )

The cap on the H board is a separate problem.. I can either sell you a new cap, or a whole board, I've got lots of both.

your negative video problem is indeed coming through the RCA cable, so either your quad decoder or RGB switcher board is bad:


http://www.curtpalme.com/Barco1208_Layout2.shtm

What I need is the 762XXX part numbers off the boards, that should be stamped on a white sticker somewhere. THe numbers on the top white sticker are the serial numbers, which don't help.

You'll also need to adjust your G2 settings for the new tube, but we'll do that after we get the image back. Email me those part numbers at curtpalme@shaw.ca

Thanks!

[mishaux]

Ha!

Yeah, the whole process sort of ground to a halt this spring when it warmed up outside and I didn't want to be lurking in the basement. Now that the weather has gone south again I came crawling back.

Will send some part numbers over in an email!