This LLC-1700 PC Board replaces the following previous PC boards: 1300-1 for LT-50 thru LT100 with wind-up timer. TC-100 and ETM-30 1300-2 for SM models without Auto Drains 1300-3 for SM models with Auto Drain 1300-4 for SM model Slaves with Auto Drains and LT models 1300-6 for HC9 thru HC-18 with CP1 and LT models