Jungle IC and on screen display

[Floyd Gilmour]

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

 

[Floyd Gilmour]

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

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.

 

[Michael Kennedy]

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

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

 

[Jerry G.]

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.

--

Jerry G.
======


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