Home Forums General Discussion Technical Questions Older MAC PMSSC operator

I have an older MAC PMSSC operator with speed and power boards on a Miprom hydro. The boards were all changed about 6 months ago in the operator. Now, the fuse is blowing on the power board. On test mode, when I replaced fuse, if I open the doors they have no control and go full high speed and slam. When I close the doors, the fuse on the power board blows instantly. Anyone ever had this type of issue? No prints or operator info. Thanks for any help!

I found some info that the power transistor is failing causing this issue.....anyone know what might be causing this issue?

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

its made by ECI in Florida

Thanks for the info!

Under the plate the board is mounted on you will find a transformer and capacitors. Change bad capacitors your back in business.but the upgraded boards are the way

Thanks, I changed the capacitor underneath and still had the same issue. Upgraded to the 104 board on and it’s smooth sailing.