Cross-posted from http://wiki.makerbot.com/forum/t-294...em#post-962887
There is some good info there as well.
More thoughts. I had wired in some LED lighting during all this and noticed a distinct flicker and drop in in the light level as the motor coughed and sputtered. I also noticed the same thing when the extruder or ABP heaters turned on. I never had a volt meter on the PS but I assume it's not maintaining a constant voltage.
Upon inspection I discovered the included PS was only rated to 22 amps on the 12v lines. And these power supplies are frequently "dual rail" or "triple rail" which means there may actually be two 11 amp or three 7amp 12v (or some combination) of supplies inside. I had the extruder controller and a stepper controller on one pigtail and the two other stepper controllers on the other. If this is indeed a dual or triple rail PS, I think we could easily be overloading it, especially as indicated by the flickering LED's. I also assume this could kill power components pretty fast if you driving them from an under-volted and unstable PS. In retrospect I should have thrown the voltmeter on the 12v lines to see what they were doing, but hind-sight is always 20-20
So, I upgraded the PS to a Corsair 650w "single rail" PS. I like single-rail PS's much better because you don't have to pay attention to what's getting plugged in where, to keep it load balanced. There is now, no noticeable LED flickering under any combination of loads and I am quite positive that the included PS is marginal at best. If someone is really interested I could pull the bottom off, again (for like the 15th time), and plug in the old PS and see what the actual 12v voltages are under load.
Also during this testing I have discovered my ABP no longer gets up to temp, it can only mange about 95c. Yet another symptom of a dying extruder controller board I suspect.