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Discussion Starter · #1 ·
My projector is a Barco 1208 modified with 9" MEC tubes installed. The projector sits as far back in my theater as it can and width is maximized on the crt's. The projector has been running very well the last few years but recently the H card went failed. To isolate the bad card I swapped it with another H card from a known good 1208, and the projector ran ok but with noticable ringing on the left side. At that point, I thought the H card I put in could be bad for ringing so that prompted me to repair my old H card.


I fixed the bad h card and the problem was one of the deflection mosfets. I searched the internet but could not locate this part anywhere so I took another similar mosfet out of a Barco 808 H card. The Barco part number of the 808 mosfet was different but the 808 h card looks so similar I tried it anyway and with a successful outcome.


So when I swapped my original H card (that has been fixed) in my projector it runs normally but still has the raster ringing that I did not notice before. And none of the coils on either the H card or the deflection switching card look bad visually.


This leads me to suspect a problem in either the chassis or wiring to or from the deflection yokes and/or deflection switching card.


There is only one thing I have found that helps and that is to increase the scan rate from 960p to 1080p. At 1080p, the ringing is almost gone. But I would rather run at 960p (for other reasons) and it still bothers me that this ringing suddenly appeared at the same time my H-card failed.


Does anyone have any thoughts about how I should proceed to isolate and repair this ringing.

 

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Discussion Starter · #2 ·
With help from another person I was able to fix the problem! It turned out to be 3 resistors (R13, R23, and R33) on the deflection switching board. Had I swapped out the delection board, that would have fixed the problem as well.


These 3 resistors do the same thing for the sweep of each color and there is a special fusable lead that had melted on each resistor. Once I found the open lead it was just a matter of soldering the leads together again. Apparently, when I blew up the H card there must have been excessive current through all of these resistors that caused the leads to blow.


My picture is looking perfect again.
 

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I seem to have this bad on my 1209s and it is red in color mostly, I have gotton rid of it for the time being by expanding my horz size way beyond the screen and then bringing proper image aspect ratio back by adjusting the porches on my vp50pro scaler, 100% clean image, ever CRT(at least in my usage) has some junk on the edges including slight convergence/geometry issues that are pushed off screen by doing this, the end result is a 100% perfect image corner to corner


-Gary
 

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Discussion Starter · #4 ·

Quote:
Originally Posted by Gary Murrell /forum/post/19671959


I seem to have this bad on my 1209s and it is red in color mostly, I have gotton rid of it for the time being by expanding my horz size way beyond the screen and then bringing proper image aspect ratio back by adjusting the porches on my vp50pro scaler, 100% clean image, ever CRT(at least in my usage) has some junk on the edges including slight convergence/geometry issues that are pushed off screen by doing this, the end result is a 100% perfect image corner to corner


-Gary

Considering how easy it is to check the next time you happen to have your cover off I would just look at each of those resistors visually on the switching board. They should all look the same and should all have the solder fuse where you can just see it fully visible. If the resistor lead is still electrically in one continuous piece its ok. OTOH, if it has split open you can just solder it back together again.


Its super easy to check and free to fix them if any have opened up. Even though you have compensated the picture, fixing a bad component in your projector may help everything else run cooler and last longer.


In my case, those resistors sure made a difference from lots of ringing to none at all.
 

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did the ringing cause you convergence issues on that side as well? I have red convergence problems there and like I said the ringing is reddish in color on my 1209s


thanks for this BTW, i'll be putting in a new quad/eht soon and will take care of this(check it)



-Gary
 

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Discussion Starter · #6 ·
I never saw any convergence issues but I sure saw a nasty geometry issue. And you can even see from the picture above how it changed the color balance on that side of the video. Keep in mind also with my breakdown all three colors ended up in an equally open state. Which meant the horizontal lines on the left side of a white grid pattern remained white even though those same horizontal lines appeared badly warped as they passed through the ringing area. If you only had 1 or 2 colors open I can imagine you would indeed see something very similar to bad convergence since the color affected would be warped while the good colors would still come through fine.


But I never ran the projector with just 1 bad resistor so I can not say for sure.
 
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