Washed out colours and black is red

[Vicked]

I've recently hooked my Neo-Geo MVS cabinet up to a J-Pac and ArcadeVGA. The colours on the monitor aren't right, blue is OK, green is a little iffy but black is basically a dark red and red isn't displayed properly.

Its hard to explain, but the colours look washed out with a greenish hue.

The motherboard in the cabinet was stuffed so not sure if the colours were working fine before or not.

Is there anyway to fix this? I've played with the controls on the monitor board and got it looking as best I can. Will a cap kit help?

I'd really like some help on this...

[SirPeale]

So this is the first time you've been able to get it up and running?

Unplug the J-PAC from the harness and turn the cabinet back on.  Is there still a red hue to the screen?

Oh, and make/model of the monitor, please.

[Vicked]

Yes, there is still a red hue to the screen when the J-Pac is unplugged.

The monitor I have is an Orion. There are a few numbers printed around, but none seem to be the model number. According to this page (http://www.jomac.net.au/mon.htm) however it is clearly an Orion 2018 Early (http://www.jomac.net.au/Orion%20PWB-2018.jpg).

[SirPeale]

Sounds like your red drive transistor on the neckboard is blown, OR the red drive is turned up too high.

On the neckboard there should be adjustment pots, one of them should be for red.  Try turning it down until the red wash goes away.

[Vicked]

I have tried adjusting the Red. The problem is if I turn it down I don't get any red. The only way I can get some red at all is to turn it up really high - but then black also takes on a reddish hue.

[SirPeale]

For giggles, inspect the input pins for cracked solder joints.

Your other colors are just fine, brightness-wise?

Could be a bad red gun in the tube, maybe?

Ken?  I'm floundering here!

[grantspain]

looks like the red background is too high,usually you will find a pot for each colour background and gain,i have had a similar fault where the red transistor goes on full drive,in that situation i had to replace it,otherwise look for broken track,broken pots possible even a tube gun fault

[Kevin Mullins]

I'm not familliar with this particular monitor, but there is usually at least TWO adjustment for each color on the neckboard, and sometimes a third on the chassis. (just have to look) 

Example : RED DRIVE and RED BIAS / CUTOFF
Turn drive down and bias up. (or vice versa)

Also try turning the SCREEN down a little on the flyback.
Or the brightness.
Don't discount the other controls just because you have a color issue.

Ditto grantspain:
Could be anything from a bad pot, transistor, capacitor, tube gun, or just adjustment.

Just guessing here..... sometimes it's just a matter of playing with it.

[D_Zoot]

Sounds to me more like you have a gamma problem with the tube, also known as a "gassy" tube or a tube with poor cutoff.

It's indicated by the fact it sounds like you can get tons of red when you overdrive the gun by turning up the red adjustment (red hue to screen), but anything below that point results in insufficient cathode emission and poor red output.

The only way to know for sure is get a tester/rejuvinator on the tube and see what's up.  Perhaps there is a TV shop in your area that would test the tube for you. 


Good luck!
D

[grantspain]

power on tube without signal,if you have a red screen then tube if not then swap your colour inputs to see if the fault goes from red to blue for instance,then your looking at transistor drive fault

[Vicked]

Thanks for all the suggestions guys.

I moved the cabinet around a bit on advice from another forum, something to do with the earths magnetic field. That didn't fix it - so in disgust I just moved it where I wanted it to go and left it.

Then when I turned it on 6 hours later.... It worked! So I'm not sure what the problem was/is - but now it looks perfect. I'm not moving or adjusting anything again, unless it stuffs up.

[grantspain]

 because the fault has gone after you moved it means you have a bad solder joint on the chassis,probably on the neck card around one the drive transistors