Red color does not show [MVS board]

Well, after my MVS broke down after a burned down 150 in 1 cartridge, thanks to a short-circuit.
After that i needed to change my MVS board but you can read my other thread about it.

It took half a year for the new board to arrive...half a year...

And now i connected it and the colors are all screwed up.
In the test screen the red color is missing, green and white are there though.

When i play a game its all green....I hate it and im really angry because of the stuff that happened before it.

I just really want it to work

Please help me. Thank you.

Note: I am not familiar with electronic wiring and stuff so please refrain from using terms i dont get.

First of all, if the Neo Geo allows you to play a game (even if it is only in green) then there are a lot of things that are NOT broken (otherwise it would fail the self test during startup), so that is good.

Start with your display device and work your way back from there. Make sure everything is connected properly. If possible, connect something else to the display and see if it works with all the colors. I cannot be more specific without knowing more about your setup. If everything is okay there then move back to the RGB output pins of 56-pin connector on the Neo Geo board and check to see if there is any voltage there with a digital voltmeter (do not use an analog one because you might get magnetic kickback from the coil!). Look for damaged or gouged traces (those tiny wires under the laminate) on the board in this area. Next check all the resistors next to the 56-pin connector (they convert the digital color bits into analog intensity voltages). Do this with the power off, using a multimeter to measure the resistance and make sure it is close to what is printed on the board. If that is okay then check the voltages of the pins on the "xx74LSxxx" chips behind the resistors - the best tool for this is a logic probe, but if you don't have one then a digital (again, not analog!) voltmeter should at least be able to tell you if the pins are "doing anything." You can easily find datasheets online if you find a pin that looks suspicious (Google "HD74LS273P datasheet" for example). If you can convince yourself that the nearby 74LS chips are okay then look there should be some palette RAM chips nearby which will probably be a little longer than the 74LS chips and will be sony "CXK..." (on my MV-1F board, they are CXK5863P-30). Most likely the self-test would catch it if there were a problem with the palette RAM, but if nothing else seems to have a problem then replace them. I doubt the problem would go any deeper than the palette RAM. I can't be more specific without knowing exactly which Neo Geo model you have. Good Luck!

Wait, if you are only seeing green and white then you are missing red and blue.

Try cleaning the edge with a pink eraser first then try again.

I would think that the color resistor bank has some burned resistors of the output 74LS273s. I would discount the pallete RAM only because if there was an issue there, it would kick an error before trying to start the program. The same applies with the later 6264 pallete table RAM, though. As a caveat, the code canot tell an open address line so that the pallete B ram may still be an issue.

Also, if the white is there, the 3 primary colors may still be round... hmmm....

Okay so it would seem that I made a mistake.

The color blue is also there, so is green and white. If I go to the test screen I can clearly see the 3 color cubes except for red. It's all a very clear color and not distorted at all. The Red cube on the other hand is completely black.

I currently have no time to check the inside of the cabinet because i'm at work currently.

I was thinking the red color might not show up because of the short circuit that happened (read: http://www.neo-geo.com/forums/showthread.php?223583-What-a-great-day!-(RAGE) )

Anyway I really hope it's not my arcade screen because I can't afford it to replace it. Let alone that I really don't wanna replace it.

Thanks for the help so far hopefully we can figure this out.

If youre seeing white, you should be seeing red, cause it takes red to make the white.

Try swapping the red and green pins on the MVS edge connector, and see what happens then.

NEO-GEO man said:

If youre seeing white, you should be seeing red, cause it takes red to make the white.

Try swapping the red and green pins on the MVS edge connector, and see what happens then.

Click to expand...

Is it possible that you could post a picture of the RGB pins? I don't wanna go around and break stuff because i'm a total newb when it comes to these things.
Also since you say that it takes red to make white, does that mean that my arcade screen is still fine? I thought it could be that something inside the TV broke and therefor it does not display red.

When you say its all green, do you mean there is no other colour at all? So you get no whites, no yellows, no cyans?

When the crosshatch test screen comes up, when you start up with no cart, what colour is it? It should be white.

When you look at the white box you say is still there, would you say it is a good white, or is it green?

If its green, id say youve got a couple bad joints on the edge connector, and this is why i want to see what happens when you swap a couple colours around on the edge connnector. If you move the green to where the red should be, you should see green where it says red, or red where is says green, or HOPEFULLY youll see both colours, but over the wrong names.

Yeah ill post an image of the edge connector, which is where i want you to change things first, then you can look at the other end of the RGB-S lead.

It does indeed take red to make white, when you see full white on a CRT, it is 255 green, 255 blue, and 255 red. That means all 3 are full on.

Try this: http://www.hardmvs.com/manuals/Jamma2NeoGeo4SlotPinout.pdf Remember to look at MVS, although they will be the same for this issue.

Solder side is the bottom side of the board, and parts side is the top. Green is on the bottom, and red is dirrectly above it on the MVS connector.

Thanks alot for the help!

However, i cannot figure out how this works, or how to switch them around

Care to post a picture where the exact parts are and explain how to switch them around? Would really really appreciate it!

Again, thanks for the help and hopefully this will solve the problem.

I could if i had a digital camera, but mine is dying a slow death at present. Its the big long plug that connects to the front of the MVS board, as you look at it, from the left itll start will 2 black wires top, and 2 black wires bottom...

I asked around some more and people dissagree with your theory about it being impossible to make white without red. They say that white can always be displayed because white is not a color.
So maybe it's my tv afterall?

They are full of shit then arent they. Ill bet a week's pay on it, with no red in the picture, youll get cyan where you should have white. Anyone that thinks im wrong, cut the red wire on your RGB connection and see what your white square shows then.

When it comes to TVs and other displays, there are 3 primary colours that make every colour you can use, unless it is digital, in which case it can only make most colours due to their pathetic colour rendition.

Those 3 primary colours are RED, green and blue. Hence the name of the best possible analog connection, RGB, or RED GREEN BLUE.

Black on your screen is equal to 0 red, 0 green, and 0 blue ( on an analog CRT, in the case of a digital, the lowest is 16 )

White on your screen is equal to 255 red, 255 green, and 255 blue. ( again only on analog, digital colour space is only 16-235, not the 0-255 you get with analog, allowing blacker than black, and whiter than white, and substantially better contrast ratios )

So if you have no red signal, when your NEO-GEO calls for white, your display will show 0 red, 255 green, and 255 blue, in which case youll have CYAN.

This is how any standard display works, so if they wish to dissagree, that is their problem.

If you want to prove this without a doubt, get three torches ( flash lights ) and put a red filter on one, a green on another, and a blue on the other, then shine them on a white wall, first shine on the green, the white wall looks green, add the blue, the wall now looks cyan, finally adding the red the wall will look WHITE.

How about one of the RGB guns (red in our case) in his monitor has gotten damaged and is short circuiting. Cyan Hue to the screen, no red, and white when needed..

Yep, that is a possible issue, and that is why i want to see what it does with the red and green wires swapped over, this way we can see if its the monitor or if its the MVS.

I agree that if the monitor shows white, the monitor should be capable of showing red. Most of the color bits come from the 74LS273s, but I think some of the RGB color bits come from the 74LS05 hex inverter. If the hex inverter is okay but the red-controlling 74LS273 (or its output resistor bank) is fried then that may explain the situation where white (including red) is displayed but uniquely red colors are gone. You could try momentarily jumpering the red pin with the green or blue to see if you get any red on the color blocks as a quick easy test to verify that the monitor can show red.

That is very simular to what i asked him to do, but then you can see what i was told then...

I hate hijacking an old thread, but being unable to find something closer on the forums to post to and being more of a forum stalker I do not have the permissions to post a new thread.

However, I just wanted to reach out to see if anyone had any tips or if my ideas were correct. I recently bought my first arcade cab DOA from a guy (MVS4 slot) and purchased a new power supply, hooked it up and huzzah! I have sound/lights/buttons! However, the celebration was short lived. The sound is awful (I think the speakers are blown... no biggy) and the monitor... dim as can be (adjusted pots, still dim, but not unbearable), but when I went into the hardware test, I found my color channels seem to be switched.

The red square displays blue, blue square displays red. Everything else seems fine. I have messed around with the pots, but it seems obvious that the wires are crossed on the connector to the MVS board. I can't imagine this is something wrong with the monitor itself.

Now time for the question! Has anyone heard of the actual connector interface having the wires swapped for the RGB channels? The wires seem to be color coded in the right spot, but I realize that means nothing. Is there a very off chance that this could just be a problem with the monitor and not the connector? How about on the board itself?

Is my only recourse to fixing this actually pulling the wires out of the harness and swapping them manually?

TIA and once again my apologizes for hijacking your thread (just unable to start my own).

Ok, just giving a little follow up in case anyone cares to read about it. I looked up the pin out earlier and noticed that it seemed like the red/green were fine (as per the colors), but figured I would trace it through the machine. I found where they attached to the monitor chassis, and searched WG site for a pin layout of the board.

For some reason the molex in the adapter attaching to the chassis had the R and B channels swapped. After prying the pins out and reseating them in the correct spots according to the WG site, I powered on the machine and my colors are normal. Woo!

The person I had purchased the machine from had said everything worked fine before the power blew, so I don't know how he missed seeing his red/blue being swapped, but he probably just said that as a way of making it seem like a better bargain. Oh well, a quick cable swap and it was a great bargain Now to work on the speakers.

The RGB harness is probably connected backwards on the monitor chassis.

If the RGB harness was connected backwards, it wouldnt work due to there being no sync. No sync and there is no picture at all.


Swap the R and the B and that should fix it, there might be some connections on the monitor chassis its self that have been reversed. Depends on the monitor.

NEO-GEO man said:

If the RGB harness was connected backwards, it wouldnt work due to there being no sync. No sync and there is no picture at all.


Swap the R and the B and that should fix it, there might be some connections on the monitor chassis its self that have been reversed. Depends on the monitor.

Click to expand...

Yeah but these monitors don't always have a 1-piece connector. A lot of the Neo cabs had a two piece connector with the sync on a seperate three pin connector by itself. After I thought about it it still didn't make sense. Had to be just a swapped wire instead. Glad he figured it out already.

This was actually a single molex connector with all of the wires slid and locked into place. Which makes it even stranger that someone would have had it setup like that.

Perhaps they were repairing and just threw the cables back into it without checking.

The other cables (V-sync, H-sync, Ground, and Green) were all in the right spots. Was a pain trying to remove the wires, but once they were out it was simple sliding them back in.

thank you guys for all of your help

Reminds me of my old thread..problem I was having with no Red..

http://www.neo-geo.com/forums/showthread.php?216349-Big-Red-Monitor(Red-Cap)-Issue&highlight=

Loss of RED.
A few months ago I was moving the Memory Card board reader cables around with the cab on trying to locate where a break in wires or ground problem was when I noticed the cables lie bumping another main wire that goes from the motherboard to the monitor..When I lifted the wire that goes from the motherboard to the monitor it started to cause the color fluctuation/loss or Red...
I traced that wire that goes from the motherboard to the monitor along the left side of the cab and came upon a Molex Connection(4 prong) and found that it wasn't pressed all the way in..With a general feel it felt ok but upon putting more pressure/pressing the molex plug together harder it had more to go..This solved the "problems" I was having as a few days later I plugged the Memory Card board reader cables back in and no more interference..

What was going on was,when I'd pull the Memory Card board reader cables out of the motherboard they'd no longer push-pull on the Molex Connection wire going up to the monitor from the motherboard when I opened up the control panel so I figured it was the mem card cables that were the problem when all the time it was just that one wire(Molex Connection) going from the monitor to the motherboard..

I am sooooo Glad my Baby is working great again...