DMD Gas Question

thejefu

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If a DMD is otherwise bright and perfect in 95% of animations and runs a DMD test fine, can one rule out outgassing if only very specific animations are fading?
 
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thejefu

thejefu

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That sounds like you have a data line problem rather than a degassing DMD. Have you tried reseating all the DMD feeder ribbon cables?
What I figured.

Reseated everything to no avail. Tried a known working cable. Will pull the boards and investigate.
 

russdx1

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Are the animations that are fading light more pixels then others? Have you got a video of the issue?
 
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thejefu

thejefu

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Are the animations that are fading light more pixels then others? Have you got a video of the issue?
A good example is the high scores. High score 1 lights fine, 2 fine, 3 fine, 4 and 5 the initials are almost completely faded. I believe as it goes down the score board, the brightness of the initials decreases.
 
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G-501

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Doesn't look outgassed from that video IMO. Scores #4 and #5 just look blank (#4 does appear to have a small dot in it).

Have you tried a factory reset to see if that helps? Maybe non-volatile RAM has become corrupted.

Failing that, try another DMD and see if its the same.
 
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thejefu

thejefu

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Doesn't look outgassed from that video IMO. Scores #4 and #5 just look blank (#4 does appear to have a small dot in it).

Have you tried a factory reset to see if that helps? Maybe non-volatile RAM has become corrupted.

Failing that, try another DMD and see if its the same.
Oh it happens all over the place, but always in the same places. Certain elements of animations or whole animations are fading increasingly. Other animations appear absolutely fine.

Unfortunately I don't have another DMD to replace it with. Will trying to troubleshoot.
 

Jagspete

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When I had one go it started off occasionally, in small areas once warmed up, and eventually affected 50-75%
 
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thejefu

thejefu

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F3 (500ma) HV fuse just blew in my XPin on boot. Did my DMD just die in 5 days?


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Calimori

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I was just thinking to message you about sending a good DMD.
I assume all the test lights were fine, what tests showed the xpin wasn’t working correctly?
I just fitted one to Tommy and still have a solid lit DMD, a very different issue but worth knowing what good looks like.
 
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thejefu

thejefu

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I was just thinking to message you about sending a good DMD.
I assume all the test lights were fine, what tests showed the xpin wasn’t working correctly?
I just fitted one to Tommy and still have a solid lit DMD, a very different issue but worth knowing what good looks like.

Struggled to nail it down precisely. I got a DMD extender thus bypassing the HV. Worked fine which ruled out data and meant out gassing or the HV which I’d previously only tested at the test points. Test lights were and are fine.

After the DMD extender experiment I then went back to the HV and the DMD and reseated everything 8 times and changed all the connectors. My seemingly undervolted DMD then became overvolted with a very fuzzy image vs a faded one. Ruled out out gassing, but then a 400ma fuse popped in front of CN5.

When I went back to the header pins, pin 4 of CN5 was putting out 104+ volts. I wish I knew exactly what was going on with it, I only feel comfortable blaming it since the issue started when I put it in. I’d just refused to even consider the board as a factor given its newness and having dropped money on it. Brain played along and just went straight to outgassing, ignoring the board I’d just installed.


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thejefu

thejefu

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One thing is for sure on Data East is you always find something when you change those damn connectors. They’re awful.


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Calimori

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That is a shame as it does look a good bit of kit.
I tested the new xpin in mine and it was kicking out on pin 1 -118v and -102 on pin 2 from the HV to the DMD. Higher than expected and a drop of 16, same DMD results as when it was a drop of 14.3, fully lit. I think the HV is testing out as strong on this one.
 
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thejefu

thejefu

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That is a shame as it does look a good bit of kit.
I tested the new xpin in mine and it was kicking out on pin 1 -118v and -102 on pin 2 from the HV to the DMD. Higher than expected and a drop of 16, same DMD results as when it was a drop of 14.3, fully lit. I think the HV is testing out as strong on this one.

I’ll hopefully work with the manufacturer and find out what went wrong. Will update the thread once we get to the bottom of it.


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thejefu

thejefu

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That’s appalling, I’ve been recommending the xpins over rottendog, what have you replaced it with?
I had an original board with a lot of ugly repairs on it which I didn't want to clean up. Bit the bullet and just tidied it up.

I've heard nothing but good things about XPin and I can't completely rule out that something in my machine didn't blow it up (other than I haven't 'fixed' any likely cause and we're operational).
 
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thejefu

thejefu

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Heard back from them. Suspicion is the DMDs getting long in the tooth and pulling excess volts causing the PSU to fail. A little suspicious since DE power supplies are the most temperamental things in the world and yet the original board hasn’t failed whilst a shiney new XPin did.

Replacing a part on the XPin to get the 68v rail back


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Pick Holder

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Was just going to add it could be display pulling voltages down.

For some strange reason I thought that on either the Rottendog or XPin boards you had jumpers to change the voltages slightly. I am wrong on this. Perhaps this was on another board......