Wei Ya contrast Adjustment, monitor bowing?

[dougman]

I might be blind but I cannot seem to find the contrast adjustment on the wei ya 825HR chassis.

It seems to be set at max contrast and everything looks like crap. dark colours are way too dark, and light colours are way too bright.   Brightening up the monitor by the brightness adjustment or through the flyback just makes everything start bleeding colours.

Any way to adjust the contrast?  I would even consider soldering.   


EXTREME bowing of the monitor is present also. this is the worst I have seen. 

I made some adjustments to the rings on the back, to take away some of the horrible convergence problems. but the bowing is crazy.

[Ken Layton]

Bowing would be "Pincushion" adjustment. I don't know if this chassis has a contrast adjustment or not.

[dougman]

edit: no wait, RGB gun adjustments dont do anything. doh!


ok, i fixed the contrast by playing around with the RGB gun adjustments.

but the bowing is really kinda annoying.  Things warp as things go through that area. 

[Ken Layton]

Look for a pincushion (or side pin) adjust pot. Is this the correct chassis for your application?

If nothing else corrects it then Alva Amusement sells the correct Wei-ya yoke to work with that chassis for about $15. That'll guarantee no bowing for sure.

[dougman]

found the pincoushin adjustment. W00t!

now to figure out how to fix the messed up contrast.

I found this pic in another thread.


There are 2 other pots on the board, it looks like it is a VLINE and a B+ADJ.

I don't suppose those will do anything right?

[dougman]

This is with max gamma in mame, and really high gamma in ati control panel to try to dull the contrast. :/

this is the monitor when the brightness is normal so the colours don't bleed. notice you cannot see any background.


turn up the brightness to see the background. everything is super bright and washed out and bleeding.



the grass is suppose to be green.


everything is bleeding everywhere, just so i can get some green on the screen.

[Ken Layton]

I noticed on the picture of the monitor main board there's 3 pots off to the side. Are those red-green-blue input pots? There should also be red-green-blue adjustment pots on the neckboard.

Almost sounds like the video (color) input is being overloaded with too strong of a signal.

[Kevin Mullins]

Ya know...I looked right at an 825HR I have and didn't see that pincushion pot.
(geez, what an idget....it's right there) Saw it in the pic you found.

No contrast adjustment at all though.

On the chassis:
R-Gain
G-Gain
B-Gain

On the neckboard:
R-BKG
G-BKG
B-BKG

I'm assuming the ones on the neckboard are the same as the "drive"..... Ken ??

[dougman]

Ok, there is a workaround with the new mame builds.
They now have contrast brightness and gamma correction in software.

The optimal settings I found in mame, is Brightness 1.50, Contrast 0.250, Gamma 1.50.  There is still a bit of contrast/brightness problems but it is better than nothing.
This will make the games look normal.  I am happy with that.