There were lots of problems with the original board arrangement on those operators. There is a real slick replacement board manufactured by PCI or PMI (I think) that is not too expensive and really works well. It is simple to adjust and has an LCD screen to tell you what is happening on it. I replaced several a few years back and never had to look at them again. One or more of the bridge SCRs are shorted and usually is caused by trace problems on the boards. and stalling the doors with the torque set too high. This causes high current in the motor and that blows the SCR/s
