CarnEvil WG with Red Tint

Betelgeuse

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I just picked up a CarnEvil that is giving me trouble. The game worked great for the first half hour I had it home and then in the middle of play the screen tinted red. The picture is still visible and the drive and bias for all the colors seem to still be working. I just can't remove this overall red tint to everything. I have tried reseating all the connectors and the neck board with no change. Any suggestions??
 
if you're a solder wizard, you can try reflowing the color drive transistors on the neckboard. these neckboards commonly have problems with lifting traces there from all the heat they generate. also check for cold solder, of course.

optionally, if the game's been sitting in a shitty place for a long time, your color pots could be dirty. make note of their current position (or the original position before you messed with them) and while the game's off just turn the pots from extreme to extreme (all the way left and all the right right and back) a few times.

otherwise, you're probably, and I hate to say this, looking at a bad tube.
 
Which wg monitor??? It makes kind of a difference. WHixhever one it is let us know and we will get you a pdf manual.

In either event, once youve figured out what you have, pull the red drive transistor from the neckboard.

-Still have a red tint? You have a shorted red gun internal to the tube. SOmetimes this can be fixed with a rejuvenator, sometimes it cannot.

-Red is now gone? Then the tube is probhably ok, either that transistor has failed or something driving the transsistor has failed.

If your one of the unlucky few to have a k7300,k7400, or u5000, id almost bet you need a new neckboard as they tend to totally cook themselves.
 
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most likely it's a K7500 -- what they shipped with (unless of course it's not dedicated). I don't even think Carnevil has a scale-down dipswitch, but I've been known to fuck up from time to time. :)

if you go the transistor removing route, the transistors run in the same order as the color bias pots.

by reddish tint, are you saying the red bias is just higher than the rest despite adjustment, or the screen is exclusively red, as in the green and blue primaries are not present at all?

cause I've seen in a couple different instances where Midway JAMMA harnesses had bad video signal pins in the harness too.
 
It is a dedicated CarnEvil cabinet, 25". I'm trying to determine for sure if it's the k7400 or k7500. The board looks identical to a pic I found of the k7400, but I'm not sure how similar these 2 would be. Isn't the k7500 a medium res monitor? I thought CarnEvil was standard res...

mecha187, it seems like the red bias is really high. If I turn up the green or blue really high I can still make the whole screen turn green or blue, but at any reasonable levels they are tinted red. The red bias and drive pots do still seem to alter the intensity of the red, but I can't get it to normal levels.

I took the neck board off and looked for cracked solder/traces, but didn't see anything. I may try to remove the red drive transistor, which I believe is the one at Q505. Also, I noticed the Jamma harness doesn't fit onto the board very snug, so I'll have to check the video output pins there too. I sure don't want to be into this for a new monitor right after bringing it home.

Thanks for all your help guys!
 
Check the video plug on the chassis too - could be a cold solder point there. Usually with red tint some other color like Blue is missing.
 
Yeah, I've tried reseating and wiggling every conceivable connector and component with not so much as a moment of change.

The 'red tint' doesn't seem to be affecting the black areas of the picture. It's almost like there's not blue/green in the whites. In the monitor tests, with normal color settings the green or blue screen test come up barely visible and the white screen comes up red. I can adjust the color bias to make the green screen come up green or the blue screen come up blue, but then it's set too high for a normal picture (ie the blacks are blue/green).

I tried putting a different JAMMA board in to see if it made any difference, but I couldn't get a picture. Maybe this is a Medium Res game, despite what the KLOV archive says?
 
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nah its std res, i had a k7000 in one of mine bitd.

if it lookd like a 7400, thats what it is, because thats what they came with originally.


pull the red transistor and see what you get. THis sucks, i had a perfect 7400 tube and yke i gave away a little while back.


heres a cheatsheet
http://www.wellsgardner.com/pdf/repair/K7500.pdf

heres a specsheet
http://www.wellsgardner.com/pdf/Spec/K7400_25.pdf

unfortunately wells wont release the service manual for some reason

as far as not syncing the sync wiring setup could be different between boardsets, or you might just have to adjust the holds. ( not all pcbs sync at the same frequency, hence the adjustments
 
it's medium res. K7500. believe me, the knucklefucks that had the game before us weren't crafty enough to change it, let alone flip dip switches. ;)

if anything, it probably runs in either.

and judging by what you're saying, it sounds like the tube's bad. I had the same problem with my K7500, got it rejuved last year, looks fantastic now.
 
...Ok, major and strange development. I was able to hook up NBA Jam and get it to work, and the picture was beautiful! So, what gives... a problem with the output on the CarnEvil board??? Maybe something with the sync that goes to the gun board?
 
oh boy, for reals?

Hook the carnevil board back up and varify it still has an issue.

IIRC theres a "25 in" rom chip somewhere on that board. Pull it and reinstall it just for gigs.


Worst case if you have a bad board, i have heard of people buying a cheap blitz99 board, swapping roms and making it work.

Heres a goo ddown and dirty test to ensure its a boardset problem:

Put board back in, is red tint back?

If so, REMOVe the red video input wire from the video harness going to the monitor.

Is red tint now gone? If so, then yes its a game boardset issue.
 
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+1 there OP

good troubleshooting strategy there. looks like your Carnevil's set for running in standard res after all.

I'm no scholar, but it could be that you have bad green and blue pins in your JAMMA harness like I mentioned previously, and that when you tinkered with the bias settings and "couldn't get it to look right" was because you were missing those signals from the board. and why did NBA Jam work fine? well... I had a Midway JAMMA harness where the sync pin and red would work or not work depending on what was swapped in and out, until I hot glued the bastards into place.
 
I removed the red lead from the jamma harness and the red tint is gone. I can only faintly see a picture, so there is a very weak blue/green signal. I tried reseating the 25" chip also and it still didn't work. I have continued this thread in the general tech forum as it seems like we've ruled out a monitor issue.
 
I removed the red lead from the jamma harness and the red tint is gone. I can only faintly see a picture, so there is a very weak blue/green signal. I tried reseating the 25" chip also and it still didn't work. I have continued this thread in the general tech forum as it seems like we've ruled out a monitor issue.

To absolutely verify..... swap either the Green or Blue input into the Red spot and the Red into one of the other color spots.

If the Red output on your board is at fault then you will have the same problem but it will show as either the Blue or Green this time on the screen.

If you still have a RED tint problem with the Green or Blue input in it's place, then you have a monitor problem.

Make any sense?
 
Ok, I swapped the green and the red leads at the JAMMA harness and now the picture is green. Wouldn't this indicate a problem with the green and blue output from the board?
 
I would assume it's your board although I don't know the fix. I once had an area 51 board that had a similar issue. It was definitely the board.
 
Definitely a board issue.

What are the voltages for each of the colors coming out of the boardset?
(wondering if blue and green are low and red is high)
 
Checked the voltages again, I am definitely getting .6v on the red output and 1.3v on both the green and blue. Apparently the .6v is closer to correct. Why would the b/g voltages be more than double and would that cause them to not be picked up by the monitor?
 
I wanted to let you guys know that I was able to find an NFL Blitz pcb and convert it to CarnEvil in no time. The game is working great! Thanks for all the help narrowing this problem down! I'm sure glad I didn't need a new monitor.
 
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