Quoted from lrosent345:Hold on a second. It is entirely possible that moving the connector toto another header fixed the problem. Over the decades, these pins get less bouncy and the headers get hotter due to increased resistance across the pin and header. As the header gets hotter, it causes more heat and more resistace. It is possible that the connection had so much resistance, the voltage dropped enough to cause the problem/. Also, one of the pins on the original header may have had a cracked solder joint.
I can't say for sure if this particular board has these problems but I like to play the odds game (I play it for almost everything in life because the universe - specifically physics - is just an odds game). I have seen a LOT of WPC-89 power boards and I have NEVER seen any problems with the lamp rows. This circuit just does not generate heat. Odds are low that this is the cause of the problem. It's often the general illumination (GI = J115/J120/J121) that generates a lot of heat resulting in burned headers and/or connectors and/or cracked solder joints. I'm not saying that this is not what happened here. I have no evidence to refute it. Just odds and experience.
Quoted from Pinkitten:I am tempted to switch them back as a test to see if the problems return, but it’s working 100% and I don’t want to tempt fate. Either way, it’s been error-free for a couple days since reseating the connectors and switching J134 and J135 back. I can’t explain it, but I’ll take it.
That's a true scientific experiment. Results that can be reproduced. The problem with headers and connectors is that if you try to do this you don't always get a true scientific result. This is because the connection is not 100% identical when you insert the connector onto the header. This is why when people complain about WPC resets attempting to re-seat J101 and/or J114 and/or J210 will result in the resets going away. Same deal with ribbon cables. Often people complain their DMD is "scrambled" and re-seating the ribbon cable fixes it.
If you want to know you should describe what the original problem was so that an analysis can be made.