[violette]

Thanks for your reply.  I’m pretty confident of the power supply I’ve been using.  It’s one of our lab bench HP power supplies, and I periodically verify the voltage needle on the supply with a DMM.  I’m running one 0.1uF capactor per IC, placed directly between the Vin pin of each IC and ground, but I haven’t acutally monitored the behavior of the voltage on a scope while the board was in operation.  I think I’ll put that on my to do list for my next visit to the lab. 

There have definitely been a few times where my connection for the 5V that runs from the control board to the matrix has come loose while the ICs have been running. One of my goals this weekend is to switch the connector out so that it has a ‘catch” to keep it from coming loose. So it’s possible some damage was done at the various times I’ve lost that connection in the past. 

There were also some shorts and missed connections on the control board when I first got it all wired, that took a few days to track down, so that might not have helped matters. 

At any rate, I do appreciate your response. If I figure out the cause, I’ll come back and update the post. 

I really enjoy looking through your site and checking out your kits and projects.  Wish I was local so I could stop by the store. 

Thanks again!

Mike

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