Stern DMD all garbled

[robm]

I picked up a LOTR yesterday that hasn't been turned on for a year or two. Checked all the fuses, and there was some fairly good battery corrosion around U210, U212 and U213. Put a remote battery pack in, and a new socket at U212 after cleaning up the corrosion with vinegar/water/alcohol. I'm pretty sure i buzzed all of these out OK. Then i reseated every single socket, plug and ribbon cable on the machine at least twice.

1st time i powered up it the lights on the playfield flashed on and off every second as well as the blanking L204 LED on the driver board. Then i reseated every IC that was socketed, and each cable/connector again and it fired up OK but the DMD was all garbled, could start and play a game OK.

After reseating everything again for the 7th or 8th time, i can now get it to fire up, garbled DMD for 3 or 4 seconds then the DMD is fine. Then after 30 - 60 secs it goes back to garbled.

Voltages to the DMD are fine (no 12V but i don't know if it needs it as there is no reading when the DMD is normal or garbled).

As i said i've reseated everything a heap of times, and am leaning towards a problem where the corrosion was - reason, after i put a new remote battery pack in and put it on freeplay, after turning the machine off for a while (few minutes) it does not remember the settings (yes the batteries are new and putting out the correct voltage).

So any tips? I found it a real pain to solder the new socket in as the corrosion made things difficult, but i'm pretty sure its all sweet as i buzzed each pin out from the top of the board to its track on the bottom and each one was fine.

PS - I've cycled it on and off a few times and sometimes i still get the playfield lights flashing on and off as though its resetting continually, others it boots fine, then the DMD goes garbled.

[Homepin]

are you SURE the 12v is not needed?

[robm]

Not SURE, but for the 30 secs when the screen was fine, there was no 12V (but i must admit it seems unusual)

It also seems strange that it starts garbled for 3 or 4 secs, then comes good (almost like it needs the right operating voltages/conditions or something i really don't know...), but then goes again after a while

[Strangeways]

Try re-seating the ROM located on the display PCB.

[robm]

Yep, reseated the display ROM a few times.

I resocketed the other 2 ICs below the battery which seems to have taken away the continually flashing lights stuck in a reset sort of cycle.  BUT, i have no sound

I'm thinking its something to do with a power supply/capacitor  issue(i'm really making this up, but it makes sense i my head) or something like that, the reason for this thinking is that when i initially turn the machine on (cold start) the DMD is garbled for 3 - 4 secs, then a relay clicks and it comes good.  Then 30 -60 secs later it goes garbled.  Then if i turn it off and back on within a few minutes, the DMD is always garbled. 

Whereas if i wait 20 mins or so to restart the machine (ie: another cold start) it starts garbled for the 3-4 secs then comes good again, just wondering if this has something to do with any capacitors completely discharging or the like....

Make any sense?

[Caveoftreasures]

I would check what settings the main power supply is at. 220 v or 240 or 200 etc.

I had a similar prob and it all related back to the main power supply setting.

I would work from that end first.

* also, have u checked the dmd in another DMD machine. My Royal Rumble had similar issues, we changed out the DMD and it never haoppened again.
Triple check DMD in another Pin n see what happens.

[beaky]

I checked a DMD on a data east, It has 12volt on the 12volt pin but i tried disconnecting the 12v and the display still worked ???
as cave man said check the dmd in another pin.
also check that you have 12v on the power supply and other 12v plugs on all the other boards.
I just think its strange that the 12v wire is there but it is not energised.

[robm]

Wooooohooooo

Well done Cavey and Beaky, was a dud display.

For interest the 12v must not be used as i checked it in Sharkey's Shootout and there is nothing there either.

So, now to work out why the sound failed.....

[robm]

So, old nobhead here had accidently allowed one of the old socket pins to jam across two of the sound ROMs, presumably giving them a funny signal - removed the offending piece of metal and everything works!!!!

thanks heaps for the help, and now to shop this baby out as i don't think its ever been cleaned, but i can't find any wear at all on the playfield.

Fun times ahead!

[beaky]

well done 

[goodolddays]

Great news .. have fun with the cleaning

[Caveoftreasures]

mark c has new dot matrix displays on his pinballspareparts site for $195 each.

http://www.pinballspareparts.com.au/index.php?crn=244&rn=558&action=show_detail