did Stern become Gottlieb ?

I have to admit I don't often play new Stern pinball machine. Wait, make 'almost never'. Lost interest a few years ago in them, and even while I can visit the local Stern distributor when a new game has arrived, I almost never do. Last time I went there to write a review of a game was for the Stern Grand Prix pinball machine.. so that's many years ago..

I did visit this dealer later when Wheel of Fortune and BDK where new, but didn't bother to write a review (as other sites like pinballnews are faster and write a more in-depth review that I could do after playing two or three games on a brand new machine). A while ago I also played a few games on a brand new Iron Man machine, but I was always more checking out things on the playfield (what to shoot for, how's the artwork, ..) than ie looking at the display.

Anyway, this weekend for the first time in many years I went to a local pinball competition. It was organised in a very impressive looking gameroom, with a sweet setup of games. I hadn't entered the competition so was playing for fun on a few of the latest Stern games (there was Iron Men, Batman Dark Knight and Spiderman next to eachother).
After playing IM and busy playing BDK, my brain finally started to work.
Wait.. all these games have a red display and not the regular orange dmd displays as we're used from Williams/Bally.. and those fuzzy animations, movie clips that have been captured and playback very badly on a red dmd.. I've seen this before !!

I've had a game like this many years ago, a Gottlieb World Challenge Soccer ! During gameplay it would show movie clips (of a soccer player passing a football, scoring a goal, ..) in a really crappy digitised format.. WCS isn't the only game, other Gottlieb games with dmd's had this too..

Stern has been doing this for a few years already, don't know how it comes I only really noticed last weekend how similar it is to what Gottlieb had been doing all time.

dmd driver board repair part 2

OK this is beginning to become a funny story, guess I can add this to my
funny things I learned page soon.

As posted yesterday I had repaired a dmd driver board. Also have one for sale, someone asked about it, I tested it in my Whitewater pinball game, and - big problem: the display came on but was faded at the top. So I emailed the person it wasn't for sale anymore. (as I thought this driver board didn't give enough voltage). Connected the original driverboard in my whitewater pin and it didn't come on anymore. Oops ?!

Anyway, I had tested yesterday the rebuilt driver board in my Dracula. Also didn't come on. Tested it in my whitewater. Didn't work. Put in the original board in the BSD. Display didn't come on and the game even started to reset every 20 seconds. Big problems !
My first guess was that one driver board was bad and maybe had damaged the cpu (and I had killed my BSD and WW testing it).

Now I started to think (finally). 4 driver boards, suddenly all bad ? That can't be happening. Time to take out the manual and double check everything.. DUH - stupid me !!
I had put on the small flatcable that connects to the dmd the other way around.
What I thought was a marking on the pcb for pin 1, was actually pin 14.

Plugged in the flatcable correct and start to test every board and every game again.

Good news and bad news. My whitewater pinball display was a bit faded with my spare and rebuilt boards. The dots in the top line aren't bright and sometimes flicker a bit.
But when the original board is plugged in, it works fine and the dmd looks as new ?!
I'll leave the game as is, and if the display ever is really bad I'll replace it and rebuild that driver board too. (I ordered enough kits from GPE)

The rebuild and spare boards worked perfect in my Dracula pinball machine. I was happy.. my 2 hours of soldering yesterday wasn't wasted. And my spare board was ok.
Final problem then - the original BSD board doesn't work. I have no idea what caused this as it always worked fine (until now when I removed it from the game to test the one I needed to rebuild). I saw the 62 volts was missing, it was a broken fuse.
Replaced the fuse but it blew again after a few seconds..
Bad news :(

Anyway I didn't have any time to check it further, so I put in my spare board and will check the board one day..
at least now my BSD is playable again. Only need to check my Whitewater as it has a strange opto problem..

dmd driver board repair

Spent over 2 hours yesterday evening working on a dmd driver board.
DMD didn't work, one of the voltages (don't remember which one) was too low.

Ordered a dmd high voltage rebuilt kit from greatplainselectronics.com, it arrived fast. Nice product for a great price (buying the parts separate at my local electronics shop would probably cost me double).

But the soldering itself.. I really hate soldering these dmd driver boards.
Parts are pretty close to each other. I did start at the top (first did the 4 resistors, then removed the large ceramic resistors, the heat sinks, and moved my way towards the bottom of the board removing parts..
resoldering everything went the other way, first bottom of board and working my way up.

Each time I had soldered in a component I checked with my dmm resistance towards the next component, to make sure they were soldered correctly and I had no cold solder joints.

And still, when I finally tested the board in a pinball machine, the score display did not come on ?!
Aaaargh ! I've been busy for almost 2,5 hour and it doesn't work :(

It was already too late to do any troubleshooting, tonight I'll continue and measure the voltages.. (and test the board in another machine).
I hope it's not a big fault and I can repair this board, because else I would'be been cheaper off buying one of those high-voltage piggy-back boards you just put on top of the original dmd driver board.


Update: seems my soldering isn't as bad as I thought - check tomorrows post.