Sega DMD acting up

[LLUncoolJ]

I bought a Viper Night Drivin at the auction a couple of weeks ago. It is approaching playability again. The display on it is acting funny. It works and doesn't have any lines out or anything. However, the top line of what ever words or graphics has a flicker effect. If there are 2 lines of text, the tops of each line flickers. It seems to improve the longer it is powered up. Any suggestions on where to start with this one?

And the scrap heap is not an option

[smartbomb2084]

Do you have the same condition in TEST mode.  Make sure the ribbon cable that sends the data from the main board to the display board is fully seated.

[LLUncoolJ]

I don't have another board. It does the same thing in test mode. I have removed the connectors and replaced them. I guess I could try to clean them a little. This thing was pretty filthy, I think it may have been at a race track or something...lots of black dust.

[Q*Bert_OP]

To me, it sounds like your DMD is dying. I refuse to say "outgassing" since the gas doesn't leave the display...it just burns up.

Check all of your voltages coming into the DMD. If any of them are low, a high voltage power supply rebuild can help an old DMD look a little better.

[Pinball Wizard]

I'm thirding that. Had the same issue on an Apollo 13 that I sold.

[LLUncoolJ]

you guys are full of good news. I spent the evening trying to get one of the black light tubes to work. If I manually adjust it, it comes on and stays on, but when they turn off, the other 2 come back on, but not the one in question. I know it has nothing to do with the origianl problem, just one of my grab bag of problems I need to figure out.

Weird on the DMD, not that I know much about them, but the whole thing lights up nicely. The flicker occurs on the top line of the graphic...no matter if it is at the top of the DMD of somewhere in the middle.

[LLUncoolJ]

Well, nothing so far has worked. So let me describe the problem in detail one more time. I will try to get a picture of it and post it later as well. But I don't want to buy a $125 display if that isn't the problem.

The graphics (or text) has a weird effect. The top line flickers, especially on the edges. This is not limited to the top line of the display. There is a scene where 2 vipers are drap racing horizontally. The tops of both cars are partially missing as well as the road lines. These missing or partially missing horizontal lines occur throughout the display, but always at the top of a graphic. Sometimes, the effect is actually wavey instead of only on one horizontal line. If this were outgassing, it seems that the places in question would always be defective (or at least until it warms up), but they are only bad when said spots are at the top of a graphic. I have reseated all of the connections, but not really cleaned them up thoroughly. From what I can see, no pins appear to be missing. However, if either of these are suspect, I could take a closer look.

PBJ, your time to shine here!
Thanks...pics to follow. 

[shardian]

You just said the magic word that confirms your diagnosis: Wavy.

The dead DMD I had to replace in Lethal Weapon also had the filckering top row on text. I just noticed it yesterday when I plugged it into my Whodunnit.

[LLUncoolJ]

So on yours, even if there were 2 lines of text, both lines would have a flickering/wavey top? As much as I don't want to lay out $125 + shipping for a display, an even worse thing would be to lay out $125 for a display and that winds up not being the problem. I am starting to suspect you may be right though. I worked on it for a couple of hours last night, changing bulbs and cleaning, and the display became dramatically better (not perfect) after it was on for about a half hour.

I think I'll continue to work on the other things and save this problem for last, maybe me or somebody else will have a breakthrough on this problem. I played it last night for the first time since I cleaned the balls, added LEDs, and fixed the switches. It is actaully funner than I thought, and the light show is about is good as it gets. I may keep it around awhile.

[Flake]

WTF?  Pics?

[LLUncoolJ]

I appreciate it PBJ, but I'll try to find something local before we go through all that trouble. I don't want to f up my TOM taking the display out of it.

As far as having someone bring one out, I might as well have them switch it out if it's bad. Trying to keep my costs down as much as possible, eventually this one will be sold and I don't want to take a hit on it.

Flake, pull the display out of your SWT and bring it over, there's a 6 pack of Blue Moon in it for you. 

[LLUncoolJ]

Yeah, Flake, bring your expendable display.  The one in his Theater of Magic is far too precious.

Damn straight.

Seriously though, I hadn't really considered it. Will they have the same connections...Bally & Sega?

[LLUncoolJ]

Alright PB&J, first rainy day I'll look into it...unless Flake shows up to collect his sixer.

[Flake]

Not likely.  Flake isnt so sure how to remove the display.  You have no idea the sense of pride I felt replacing some drop targets and soldering the wiring going to the Cannon.  Point being that I'm not mechanically inclined and I get sweaty palms when I try doing anything on these machines due to the ever present fear that I'm going to F something up.

Besides you have another display to work with right there.  

And whats all this ---steaming pile of meadow muffin--- about rainy days?  You cant possibly have any significant yard work to do as 1/2 of your yard is in shambles.  Why do you need to wait for rain to work on ---steaming pile of meadow muffin--- indoors?  Your not that busy.  

Oh yea, Pics??

[LLUncoolJ]

I have been working on it fukko. If I have a couple of free hours, great, but I can't plan for it...unless it is going to rain. You think your kids keep you going now, wait a year or 2. And my yard being in shambles has everything to do with not having large chunks of time to devote to pinball.

Oh yeah, if you want to see this thing, bring your --I'm attempting to get by the auto-censor and should be beaten after I re-read the rules-- over...and don't forget that juicy, functional Sega DMD.

[LLUncoolJ]

Confirmed...it is the display going out...shitz...oh well, play-wise, she is nearing tip top, so what's an extra $125?
 

[Flake]

Did you forget how to use a damn digital camera?  Pics ---smurfette---!

[LLUncoolJ]

No pics for you! Not until it is done at least. In diagnosing my blacklight problem, which I'm 99% sure is a 50 cent starter, I was switching them to confirm and broke another one. So now I'm down to 1 of 3 lamps. Since I'm ordering parts, I think I may switch our the purple LEDs I installed in the lower PF for blue ones. I think they will more closely match the black lights.

[Flake]

F -