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1208/2 what's this retrace line top of my tubes? anyone? Please?

444 Views 12 Replies 6 Participants Last post by  pcCinema
I have a retrace looking line on the top of all three tubes on my 1208/2 I'm rebuilding. The pic posted with terrible editing shows in red where raster is and the red line above shows where the line is I am talking about. ( new tubes not the crispy ones in the pic) It's a bright retrace line maybe half the width of raster and curved as shown.

Sorry for the silly looking example pic. I cant take a pic of the actual problem as I have the pj back apart right now.

I tried moving the yokes etc and it makes little difference.

I did the "set all controls to midpoint" and then the line was completely off phosphor and created a glow reflecting off the top of the tube if you know what I mean.

I've never seen or read about this before so I'm not sure what to look for.

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When ya figure it out let me know... I saw what I think is the same thing for the first time on a BG1208 last night and pulled a few of the boards to run in a similar vintage BG1200 tonight. Attached is a picture of the BG1200 with the vertical size shrunked down. It looks like a sweeping loop of light. I'm going to plug and play with several more boards and see if I can find anything that influences this.

I'm also seeing very odd flashes on the tubes (predominantly the red) on both the BG1208 and BG1200 on turn-on. Almost looks like a sand dune looking graphic, but just on one side of the tube face - very weird. Are you seeing any odd flashes when you power up?

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No. no flashes.

Well I have no parts or parts machine, no experience with barco's, and no service manual so I'm hoping you have some luck figuring it out.

I'll poke around but I'm at a disadvantage. Barco didn't even label the boards as far as I can tell so it's hard to tell what is what even.


I too would vote for some kind of secret AKB circuit, and I've seen the line Troy has on several Barco's. I just ignored it.
I think you can blank it out with the blanking control.l

On another note, it looks like there is an outline of a face on the green tube.

I'd save that tube and market it on eBay as the 'CRT of Turin'. Might get you a buck or two..:)

On the two projectors I'm looking at blanking is being used for the basic image, but this light show is still going on outside in the area that should be blanked.

My data 808 is doing this on the red tube, and has been for a many months now. I first noticed it after I replaced the blue and green with VDC rebuilds, but I don't think I noticed it happening before then if it was. No flashes, my red just looks exactly like what Troy's picture shows.

Curt suggested a few months ago that it is some sort of AKB.

You definately cannot blank it out, its completely outside of the raster and the blanking controls only work within the raster.

Altering raster size/shape doesn't really seem to affect the line for me.
Well. suprising to see it's not just me.

Someone must know what it is or how to get rid of it.

I could use a strip of electrical tape to blank it if it's just normal but if it's not supposed to be there I want to fix it right. Hard to imagine it's supposed to be there... It is bright enough to show on the wall.

Does anyone have a service manual for a 1208/2? I did want to look into some other things too. There is not a single empty slot so I also wanted to see if I have some optional boards that can be pulled like maybe lido or something. User and install manuals I have don't list the boards either.

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Troy, not sure if this is too late or not, but I just discovered that if you decrease V-Amp too much for the red or blue gun, shrinking the vertical size of the red or blue raster, this line appears on the bottom of the tube. Increasing V-Amp to get red or blue to match the green image will tend to push this line down into the nether regions of the tube.

I have no idea if this is good for the tube or not. But I had previously tweaked V-Amp down on both blue and red, and that's when the line appeared. I just tweaked it back to match my green, and the line is gone.
Thanks for the tip... No it's not too late it is on hold in need of a green tube.

The used green I got for it ended up sparking internally. What a dissapointment.

I need two greens now actually, I picked up an 8500 the other day that I want to fix also.

I wish that new tube manufacturer had come about in time but oh well...


Your "Tripping over crt's" fits you well Troy!

If you have the line and can't adjust V-Amp because it would cause the colors to no longer converge, I don't have any suggestions for you. And its pretty easy to do this, V-Amp and the two shifts should be pretty much dead on with the center converged as much as you can get before attempting software based convergence, as the software convergence controls have a very limited range, those 100 ticks don't go very far.
I swore I was going to thin the herd but one of those deals I tripped right over. I was setting up an NEC for a local guy and it was sitting abandoned in the corner... I couldn't just let it rot there and the price was right.

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