DMD Cuts Out After A While

tim_m

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I have a Big Hurt pin, which is a Gottlieb system 3 machine.

After it being out of use for a few months the DMD did not display anything at all and I thought it was dead. Mind you it played fine, just no display. After a day or two the display just started working but it only stayed on maybe 30 seconds and then cut out.

I've been playing a few games each day for the last week or so and it seems crazy but each day the display stays on longer and longer before eventually cutting out. Today I actually completed two (bad) games before it cut out, which was maybe 10 minutes.

The longer the display lasts the more time between when it starts to peter out and when it is completely dead (though still just a matter of seconds).

If I turn off and on the machine right away the display might last a few seconds or not at all. The longer I let it sit turned off the longer the display lasts and when it is left overnight the next day it stays on longer than it previously has.

There are no graphical anomalies whatsoever (the display has some outgassing in one corner but that's inconsequential). When it dies it is completely black like it has no power whatsoever.

No fuses seem to be blown but it wouldn't hurt for me to double check.

The voltages on the power connector on the DMD read as follows:
Expected: -112/-100/--/0/0/5/12/62
Before DMD Dies: -116/-104.2/--/0/0/5.03/12.44/65.2
After DMD Dies: -117.5/-105.9/--/0/0/5.05/12.52/65.7

Also after the display cut out one time I noticed the large R18 resistor on the HV section of the controller board seemed exceedingly hot (like I stupidly burned my finger hot). Not sure if that is normal for a 5W resistor or not.

I am at a loss to make a guess as to what the issue is, the DMD itself or something on the controller board. If something were wrong with the high voltage part of the controller board I wouldn't expect to read the more or less correct voltages after the DMD dies.

I do not have another DMD to swap to test with.

I made a video starting off with the self tests and then playing until it dies if it helps at all:


Any suggestions would be greatly appreciated. I'm trying to gauge whether this is something I can fix or if I need to get a repair person. I searched the forum and couldn't find any similar issue.

Thanks
 
Well if you had another DMD that would be easy to tell if that is the problem. It could very well be a HVP (High Voltage Power) and you are lucky GreatPlains has a kit available for more B/W and Gotlieb games.

http://www.greatplainselectronics.com/proddetail.asp?prod=GTLB3-HVP-KIT

I know I need to do one for my Congo machine eventually as when I turn the machine on sometimes the DMD won't come on until after 10-15 secs. My friend said it is either the DMD or need to buy one of these HVP kits.

Good luck and hope this helps.
 
well it continues to last longer each day, which blows my mind as to what could possibly cause that. i suppose buying a new DMD wouldn't be the worst thing even if that's not it since one corner is outgassed and it's a little annoying. just hoping someone had seen something similar before :/
 
my advice, replace the high voltage section on the dmd controller, i wont ever buy a new dmd, i buy used off ebay cheaply, and have had very good luck, like i bought 4 dmd's for under 50.00 and 3 work flawless
 
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