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Main => Monitor/Video Forum => Topic started by: cwatson237 on September 12, 2011, 02:45:53 am

Title: Monitor displaying Purple screen???
Post by: cwatson237 on September 12, 2011, 02:45:53 am: Ok, I'm a Newbie and I really hope someone can help me...

I have a WG 19K7611 in an old Double Dragon 3 cabinet that I am converting to a Multi-game JAMMA. I bought the new board and plugged it in with the screen displaying upside down. There is no dip switch setting and checking the DD3 board showed it's dip switch set to "inverted screen." I checked the yoke wires and sure enough they had been swapped sometime in the past. I swapped them back, plugged in the new board and got no image...just a light purple looking screen. The sound is still there but no visible image. I tried to DD3 board and the same thing is happening. It was working fine before I tried the yoke flipping and flipping it back didn't change anything, same light purple looking screen. Two of the caps on the board look to be leaking and I have ordered a new cap kit but they were that way before the yoke flip. I did find a rubber wedge that I believe fell off of the yoke during removal of the neck board and I have not replaced it yet.

I have tried adjusting the "screen" control and other pots and re-checked the connections of the wires. Would the bad caps do this? Does the rubber wedge affect monitor function? Any help anyone can provide would be greatly appreciated!
Title: Re: Monitor displaying Purple screen???
Post by: grantspain on September 12, 2011, 01:53:20 pm: what happens to the picture if you have no game board connected and you turn up the screen volts a little?
Title: Re: Monitor displaying Purple screen???
Post by: cwatson237 on September 12, 2011, 04:07:36 pm: I thought that is what the "screen" pot on the flyback did? Maybe I am missing something? Any idea where the adjustment for the screen voltage might be?

Thanks for replying!
Title: Re: Monitor displaying Purple screen???
Post by: cwatson237 on September 12, 2011, 04:12:01 pm: Oh, I forgot to mention...I tried it with no PCB and got the same affect.
Title: Re: Monitor displaying Purple screen???
Post by: grantspain on September 12, 2011, 04:29:52 pm: got a photo?
Title: Re: Monitor displaying Purple screen???
Post by: cwatson237 on September 12, 2011, 04:31:16 pm: Yes, I will add photos when I get home tonight. Thanks!
Title: Re: Monitor displaying Purple screen???
Post by: cwatson237 on September 13, 2011, 12:04:21 am: Here is a shot of the screen and a couple shots of the chassis...you can see the 2 bad caps, one is right behind the yoke wires.
Title: Re: Monitor displaying Purple screen???
Post by: grantspain on September 13, 2011, 06:08:53 am: i think your video signal is missing,check you have not dislodged the neck card or any connectors
check you get game sounbds
Title: Re: Monitor displaying Purple screen???
Post by: boardjunkie on September 13, 2011, 08:27:48 am: I don't see any bulged/vented caps. The dark goo on the top of the one is just glue. Thats not to say there ain't a bunch of dried out caps since they are the originals. A cap job wouldn't be a bad idea.
Title: Re: Monitor displaying Purple screen???
Post by: Rickn on September 13, 2011, 10:25:36 am: So let's back track a little... by your post it seemed like you had a good picture but reversed?
This seems to indicate the monitor was fine. I may have missed this but i think you did 2 things at the same time?? Changed the yoke leads and switched to Mame?
That is where the prognosis becomes twisted.
The fact that you have high voltage (the screen is lit is a good thing, I am thinking this is related to a signal connection, primarily horizontal sync?
Title: Re: Monitor displaying Purple screen???
Post by: cwatson237 on September 13, 2011, 11:51:12 am: I am getting sound...I checked the neckboard again and it seems to connect just fine...no resistance when it is pushed on. It seems like a missing video signal to me too but everything appears to be connected good.

The caps I was worried about have yellowish goo coming out of the side of them...you can see them in the 2 pictures, one behind the yoke wires.

I had a good picture....just inverted.(upside down) It is staying Jamma. The only thing I did is switch the yoke wires. I will try to adjust the horizontal sync and see if that has an effect.
Title: Re: Monitor displaying Purple screen???
Post by: boardjunkie on September 13, 2011, 12:30:51 pm: That is just glue....don't worry about it. Its there to secure larger components to the board.
Title: Re: Monitor displaying Purple screen???
Post by: cwatson237 on September 13, 2011, 01:34:33 pm: ok, that's good to know...I thought it was coming out of the side of the cap.

I tried adjusting the horizontal sync and the only effect I can see on screen is a faint semi-circular pattern in the upper right of the screen. When I adjust the "screen" pot I can get it to change colors(red, green) but still no image on screen.

Would the rubber wedge that fell off the neck have anything to do with my problem?
Title: Re: Monitor displaying Purple screen???
Post by: boardjunkie on September 13, 2011, 05:52:49 pm: No. The rubber wedges are there for positioning the yoke before it is snugged down.
Title: Re: Monitor displaying Purple screen???
Post by: cwatson237 on September 14, 2011, 03:21:20 am: Ok problem solved! I somehow must have accidentally adjusted alot of the pots because after a whole lot of adjustments I finally got an image...then I had to adjust the colors but after that, I got my good image back!(wish I could tell you which ones I adjusted to get it back but I honestly have no idea what did it)

Of course in my "noob figuring out what went wrong" phase I swapped the yoke wires back :banghead: so I am back to my original problem of an upside down image...but now that I know the solution, hopefully I can swap them back, make adjustments and get back on track with my first arcade project! :applaud: