My DMD is acting weird. (I've updated the original post with my updated situation.)

The pin labeled Cathode on the wiring harness feeding the DMD display is reading 113 on the DMM instead of around 75 like the wiki says it should read.

Replaced the controller board, but the didn't really solve the problem.

And the DMD itself whines/buzzes, like it's getting too much power.

What could cause the problem you mention?

All DMDs seemed to hum a little, but this one is extra loud and gives too much feedback.

A photo of the DMD acting weird? Since I changed the controller board with new from Xpin, it isn't as noticeable.

Now, just random single pixels flicker here and there while every thing else seems okay.

I also had to flip all the dip switches on the board to get the DMD working properly after install.

I'll get a pic when I get home this eve.

You the man, thanks. Just looked up outgassing, and that looks like my problem.

Now I just have to decide on replacing it with the same or going with the more expensive red color display. I think that would accent the backglass and DMD cover nicely.

By the way, pixels flicker on in spots where they shouldn't, they don't flicker out.

So, there's this other thing going on that I think might be related.

The shooter lane will attempt to shoot before the ball is in the lane. Then immediately afterwards, it will fire the ball into the lane and THEN shoot it.

This happens primarily during MB about every other time. It rarely happens on ball 2 and/or 3 of a game too.

Could the DMD thing and the shooter lane thing be related? Could it be an MPU issue?

That is EXACTLY what is happening on my machine.

You say a new DMD controller board fixed your issue? I recently install a brand new Xpin DMD controller board after my DMD went out completely.

When I swapped the DH DMD into my Judge Dredd, the DMD seemed to work, so I figured it must be the board. (Forgot I did that...)

The cable probably could be swapped too, so I'll try that tonight.

The new Xpin board does let the display work, but like I said, I had to flip all four dip switches on the new controller. The instructions seem to imply they improve the scan rate... or something.

Before I buy a new DMD, I'll yank the one out of my Judge Dredd and try that (duh!).

Although I want an excuse to get the red DMD display!

Bad news.

Luckily, I have a Judge Dredd to swap DMD stuff into DH for testing.

Put the good DMD from JD into DH, and still had a problem with ghosting pixels.

Then took the good ribbon cable and hooked that up. Problem still persisted.

DMD hums like it's getting too much juice or something.

So now I'm at a loss. It must be something further up the chain?

There are four lights corresponding over the four dip switches on the new Xpin board. Two and three are solid, number 4 is dark, but the first one is flashing. A light on the CPU is flashing too.

Not sure if that means anything because the Xpin board didn't come with a trouble shooting manual, though I do think it has that capability.

Any further thoughts would be greatly appreciated.

Okay, so I have a brand new Xpin DMD controller board installed, a working DMD display, and a working ribbon cable connecting them together... and the problem still is happening.

I have uploaded a video showing what is going on.

The first light on the utility switches is flashing. There's a flashing light on the MPU too. Not sure what either of them mean because the Xpin controller didn't come with a manual.

I pushed the troubleshooting button on the board, but all it does is scan each line on the DMD display.

You can hear the loud buzzing in the video, much louder than my relatively quiet JD display.

The only next step I can think of is replacing the MPU, as I'm pretty inexperienced in the finer points of pinball electronics. My typical approach is replace until the problem goes away lol. But, obviously, that can get expensive.

It worked on the trough issue for my JD though

Please take a look and let me know what you think or if I further video would help with the analysis. Thanks for reading!

(Note, you'll also see that I have to flip the first and fourth utility switch to actually get the display to even work the way that is does. With the factory settings, each flip in the down position, nothing really shows on the display and it instead defaults to the "Xpin" logo.)

(Note 2, I found this on Wiki: "If the voltages are too high, the panel will show sparkles, clouds or ghosting." Maybe this is a voltage issue?)

Bump

Could you recommend a good tool that I could measure the voltage with, possibly link me to a place I could purchase out from a Pinside sponsor?

I've never had to do anything more complicated than soldering in a new switch.

I'm not sure of the ribbon has a magnetic toroid. How would I be able to tell?

I rarely get weird other happenings, like the machine will act like it is searching for a missing ball, but it only happens during every 20 games or so.

Okay, bought the meter from Pinball Life.

I've been hitting Google for tips on how to use a multimeter on a pinball machine, but any tips or links would be helpful.

Got my DMM in the mail today. However, I'm not sure how to use it lol.

What do I put the setting on, where do I plug in the red and black wire to the DMM, and where should I check on the PCBs?

CAM00350.jpg

"SAFETY WARNING: Your left hand should be in your pocket, to avoid a potentially serious shock. We are working with high voltages, so be VERY CAREFUL. Keeping one hand in your pocket is a good practice to follow as it eliminates the easy electric current pathway across your heart. A DMD controller provides enough electric current to kill you!"

Okay, that makes me nervous as hell...

Hopefully, I'll be okay as long as I follow these rules. Will need to stop and pick up some alligator clips today.

What is the best way to ground the DMM? The wiki suggests a couple options.

Thanks. I'm okay with doing it. I have a steady hand and these rules seems simple enough.

However, if I don't have an update posted by Monday, call an ambulance

Just to be clear; I'm checking the header pins on the DMD controller board that lead to the DMD display?

I'm not in front of the pin right now, but the pins are exposed enough to get a reading even when the ribbon cable is plugged in, feeding the DMD?

Okay, did the readings with the settings that were suggested.

The anode and offset didn't read anything.
The 5vdc reads 10 and the 12 reads 28.

The last one doesn't seem to read right, it just says 1.

Seem right?

I had the DMM clicked twice clockwise, grounded to the braid, and touched all the posts?

Figured it out, thanks for sticking with me

All the readings are near the ranges they're supposed to be...

Except the 8th pin labeled Cathode. The wiki says it should read around 62-75, but my DMM is reading 108 to 113, staying mostly around 113.

The owner of Xpin is sending me a replacement DMD controller board after telling him about this issue. He thinks the one I have could be faulty. I'm new to this side of electronics in a pinball and appreciate the opportunity to learn more about repair techniques.

Please see my previous post about the double high reading on the Cathode pin on the display. Should I now measure the male pins on the board itself? Next steps?

Bad luck, huh? I have a feeling the problem is coming from somewhere further upstream, but hopefully this tested replacement directly from Xpin does the trick.

Installed the NEW controller directly from XPIN and now nothing will display, except for the default XPIN logo. Even that disappears when I flip the fourth dip switch.

I put in the other XPIN controller that I got first, and it still works as detailed above.

Weird!!

The Owner told me via email it had something to do with LED displays versus plasma?

We're supposed to talk on the phone about it this weekend. I'll post the results of the conversation.

Something ain't right somewhere...

OKAY, I'm back.

Installed the new XPin board last night and it is doing basically the same thing the first board was doing.

Flip switch 1 and the Xpin logo shows nice and clear.

Then add switch 4 and the display works... but it STILL has random extra pixels flicker here and there.

When switch 1 is on and 4 is off, the voltage readings are all within the general area that they're supposed to be... but only the Xpin logo shows.

I forgot to check it when both 1 and 4 are flipped, but with the original board, the 8th pin was reading 110 when it was supposed to be reading 65. I'll check it tonight with both switches flipped.