Green/White color problem

[speckone]

I am having a problem with the color on my Tovis 19" CGA monitor (http://www.betson.com/products/JCM-44-4519-02).

I have tested it with multiple inputs and I always have the same problem.  The green and white are off balance.  There is green where there ought to be white and vice versa.  I have attached a photo of an instance where there is white where there ought to be green.  There is a tinge of green to most everything in every game. 

I have tried adjusting the green drive and cutoff but this does not effect the problem.

Any suggestions would be more than welcome as I have exhausted everything I can think of.

Thanks in advance,

speckone

[SirPeale]

Wow..that's just *weird*.  I'm coming up blank here.  Esp since you already turned down your drive and cutoff pots.

Check the green drive transistor on the neckboard, see if it's problematic.

[Level42]

Huh !?!?

Logicaly speaking, the green area is now also hit by the red and the blue beam....else you wouldn't get white.

Could it be there is some monochrome /color switch on it ?

And then they would use the green input for monochrome ?

I can't think of anything else....

[SirPeale]

Huh !?!?

I see you're as confused as I am!  And in that picture no colors seem to be bleeding, so...

[grantspain]

whats the signal source?you say you tested with multiple inputs,what inputs and are they going through some kind of signal amp?

[Level42]

Just checked out the service manual. This has an OSD settings menu. Maybe you turned up the green all the way to 100 ? Should be 50 for all colors:

I read this manual:
http://www.jcmamerican.com/docs/manuals/mtg-1902ex.pdf

It's on page 11

Don't know what exact model you have, but here is the manufacturer's list:

http://www.jcmamerican.com/support/tech_manuals.asp


Here's a screenshot:

[speckone]

Here is the manual: http://www.tictacfruit.com/images/_MTG-1901-2901CN_Service_Manual2%5B1%5D.pdf

Its a no-frills Tovis MTG-1901CN

I am using an ArcadeVGA with the Ultimarc Video Amplifier.  I don't think I have tried any input without the video amplifier, but it will take me a bit to try it.  I will have to get a cable and splice it directly.

Thanks

[Level42]

OK, so this doesn't have an OSD.....rules out that option then....

The Ultimarc Video amplifier boosts the signals to what an arcade monitor wants, sometimes I think it boosts it too much. I have a J-pac, (this includes the video amp as well) and I have the feeling my colors are over saturated (especialy white is much too bright.)

I have the feeling that more recent monitors don't require the 5V that those video amps are putting out. Check out the manual again, this monitor wants 0-2,4Vpp as inputs. Anyway, this is all not of too much concern, and of course is not the problem you have because the red and blue show up ok...

Since you have that amplifier it should be easy to exchange colors. F.I. exchange the wires R and G on the interface and see what happens....make a pic if possible. This way, we can see if either the monitor or the video amp is at fault.

[speckone]

OK, so this doesn't have an OSD.....rules out that option then....

The Ultimarc Video amplifier boosts the signals to what an arcade monitor wants, sometimes I think it boosts it too much. I have a J-pac, (this includes the video amp as well) and I have the feeling my colors are over saturated (especialy white is much too bright.)

I have the feeling that more recent monitors don't require the 5V that those video amps are putting out. Check out the manual again, this monitor wants 0-2,4Vpp as inputs. Anyway, this is all not of too much concern, and of course is not the problem you have because the red and blue show up ok...

Since you have that amplifier it should be easy to exchange colors. F.I. exchange the wires R and G on the interface and see what happens....make a pic if possible. This way, we can see if either the monitor or the video amp is at fault.

Level42,

Thanks for your help.  That totally helped. I switched the R and G. and the problem switched to red, indicating the video amp.  I made a new cable, wiring my ArcadeVGA directly and everything is fine now.

Best regards,

speckone