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Discussion Starter · #1 ·
Hi, I'm stumped(whats new) by a Barco Graphics 1208s/2 that I put new tubes into. The text comes up totally out of focus and the grid extends far beyond the edges of all the tubes. You can turn down the brightness and contrast to get the letters of the display readable(otherwise they are bloomed beyond readability) but at normaly levels you cannot achieve a proper focus. Am I missing something ? THey are the same exact tube model and I know the tubes are very strong. is there some static focus pot I'm missing or some aspect of setup I've overlooked ?
 

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Paul,


So you just swapped out the tubes. Hmmm... The blooming of the picture sounds something like a high voltage problem I saw once and could be the cause of the focus issue. Have you tried disconnecting the tubes one at a time? Just an idea.


Mark
 

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Discussion Starter · #3 ·
Mark: Thanks for the response, what was the HV problem you saw ?

With mine, the overall brightness(and the blooming) pumps depending on the overall brightness of the image , as another symptom.

The quadrupler has been replaced with one loaned to me from Curt, and I think it may be from a different model. Also, when I changed the tubes, the blue had a crack in the neck, but had been unplugged from the HV because it was arcing and the repair guy knew I was going to just replace the tubes. There was a problem on the SMPS that required a transistor replacement too.

Is there something else wrong with the SMPS ? Where do I start looking ?
 

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A few years ago I had my personal BG800 suddenly bloom on me and start acting up. If the image changed from dark to light or vice versa it would bloom or shrink and sort of fluctuate before settling down a bit. When it bloomed the focus went off and the picture was about twice the size it needed to be to fit on the tube face.


As I recall, the splitter had gone bad and eventually it took out my EHT board. I just don't remember how I knew the splitter had gone bad first?!


Wait... It might have been that I knew the EHT was in hold-down and when I put a replacement in I measured the HV at the splitter and it was still fluctuating. While I was doing all this one of the two good EHT's got fried.


I didn't have to change out my quadrupler and my SMPS was okay.


Mark
 

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Discussion Starter · #5 ·
The symptoms you describe are exactly what I'm experiencing, so I'm to assume my splitter is bad too ? It was supposed to be a good one. You don't have a spare, KNOWN good one do you ? Thanks, again for the benefit of your experience.
 

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I'm sure I could salvage one economically out of a projector like an 808, or less economically I'm down to my last two that I bought new from Barco about two years ago (which I just found).


So probably an R7617447 (used) or an R762718 (new)?


Mark
 

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Discussion Starter · #8 ·
The one thats in there now is the first one you list(used) , I don't know the number that was on the original. Are they functionally different in any way ?

Email me if you can sell me one?
 

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Discussion Starter · #10 ·
Thats for SURE !! They really don't seem to like me too much. I'm not going to give up on this one though, because I've got some very nice tubes in it now and it will let me see what a big Barco can really do if I can just get it to WORK.
 

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Discussion Starter · #11 ·
To update and close this thead, with LOTS of help from generous forum members and a local tv repair guy, I got this Barco working. IT WAS THE EHT BOARD(and the quad and SMPS at first). The give away was checking the return voltage. The return voltage was only about 25 VDC when it should have been at least 32VDC. The lower high voltage supplied to the tubes by the EHT was not enough to keep the beam from blooming unless the contrast and brightness were very low. But even at very low levels the beam was not focussed, just weak enough to not bloom too too much.

I believe the original problem was cracked tubes(the blue AND red tubes were bad) which destroyed the components back through the splitter, quad, EHT and SMPS. If you hear ANYTHING that may indicate a cracked tube(hissing, spitting, snapping), I'd recommend shutting down and really looking before you blow other components.

The EHT in there now is working 99% of the time but still has an intermittant flaw which causes the blooming to recur momentarily. Some of the pros who helped me with this are sitll looking at the EHT to see if they can find a bad component. Thanks to everyone who helped me especially Cousin.It and Curt Palme.
 
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