Small pcb is your line noise filter that is also fused. Check for 120vac in and 120vac out. If you have 120 vac out, your filter pcb is good. If 120vac is at your main pcb, and control is dead, there lies your problem. You have 3 thermal fuses on this unit unless I'm mistaken. One is for magnatron (Normally closed). One is for oven cavity (Normally closed). The last should be for the stove top (Normally Open). Hope this helps.