Samsung SR-L676EV Service Manual

Also see for SR-L626EV: Owner's instructions

Contents

26 Samsung Electronics1) Power circuitPCB sub ass’y (Inverter PCB) is activated with AC POWER input when the refrigerator door is openand R-lamp relay(RY05) is activated. If the AC POWER is supplied to the power block, the smoothcapacitor(C3) gets around VOLTAGE DC(VOLTAGE AC X 2) AC POWER through rectification.2) LampIf power is supplied to the PCB sub ass’y, diac(DB4) is activated. When C4 is over 35C/DC, voltageis supplied to TR Q2 base by the continuity of diac. Then, TR Q2 is activated.When TR Q2 is activated, current flows to C5 – C6 – CH1 – PT1 – R9. At that time, current flows toPT2 and PT3.If the discharge of capacitor C6 is completed, reverse current flows to PT2 and PT3 and TR Q2 turnsoff TR Q3 turns on. The current flows to PT1 – CH1 – C6 – C5 – C8.Lamp light up by the repetition of TR Q2, Q3 on/off. Its frequency range is 30~40KHz duringon/off.3) PTC and PTC protectorPTC is designed to smooth the lighting and to lengthen lamp’s life by heating filament of lamp. ThePTC protector prevents damage from PTC by cutting off power through triac if filament emits highvoltage at the beginning of lighting.To check the PTC, measure resistance (150Ω ± 25% is normal). But, PTC resistance can be challged bythe ambient temperature and PTC operation. The above resistance value is counted in 20 sec afterlamp is off with the temperature 25˚C.