Jungle IC and on screen display

I've got a Mitsubishi M1GA 39" with weak green. I've been trying to check and trace everything in the chroma area and have come up with nothing. Maybe it's just an old weak CRT but what has been driving me crazy is that the on screen display looks perfect. The characters are either red yellow or green and they look as good as new. The chroma chip ia a M51414BSP and it shows RGB inputs for the on screen display which I assume are generated from the CPU. If the on screen display is a perfect pure green shouldn't that say that the CRTs green gun is functional? As far as I can tell I have good chroma up to the IC but after it the green seems to be out to lunch. If I try messing with the green cut off all that happens is the picture gets washed out with luminance but very little green. I replaced the chip but that did nothing and there are no more electrolytics to replace. There is a dynamic white circuit and a color temp circuit between the chroma IC and the CRT board with the drivers. All check good. Any ideas? tia Karl

Reply to
Floyd Gilmour
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I didn't realize how bad the spam was on this group. It wasn't like that before. Unfortunate.Just trying to move back up the list.

Reply to
Floyd Gilmour

The spam hasn't been too bad.. Sometimes it gets bad though.. (Giving you another bump) ;)

Reply to
Michael Kennedy

The only way you can check the video output from this IC is to put up a colour bar test pattern and use a scope to see that the video levels are all within specs. Then check that the DC levels at the CRT elements are in spec to see that there are no bias faults.

If the set has had more than about 5 years of use, it is very possible that the CRT is at fault. I have seen this before, and it was the CRT.

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Jerry G. ======

Reply to
Jerry G.

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