F1-8 switches. I have read the fault description troubleshooting. The next step is mentioned to replace the ribbon cable. RB20. Certainly give this a try but it seems doubtful to me.
Today I noticed a very distinct pattern. The unit would take calls to all landings, when the door reach fully open the controller would RCD fault. When the door reached fully closed the controller would "cycle test" and take the next call with no faults. same RCD fault at all floors when the door reaches fully open. The lock circuit drops and picks up as it should. CD relay energizes as it should. DCL and DOL signal correctly.
The room is excessively humid and hot with summer approaching (no ventilation). I noticed vapor droplets built up inside the relays. Oddly opening the door and working out some heat and humidity the fault stopped happening for multiple calls (not sure if this was a coincidence or effective, TBD)
