After you open the remote control receiver casing, remove the power supply Board alone some, LED1 does not glow, check the F1 fuse, then check the U1 resistance on the road to normal. Continue to check VDR1, VDR2, VDR3, C5, GL1, D1, D2, and other components, VDR1, VDR2, VDR3, all fuses and other components were normal, PCB partial carbonation. Before you replace the varistor, carbide parts must be addressed. If there is no original, direct replacement for IOK331. Analysis of reasons: high peak pulse occurs at input power voltage varistor breakdown caused by conduction, fuse F1 fuse. Replace the damaged components, power supply board 12V output correctly, replace the receiver and remote control system back to normal.