See the figure below, press the "thin block bake" button, IC1 ⑩ pin output low, so Q5 conduction through R15, baking relay RY2 pull, turn the baking heater circuit (see Figure 1) 220V mains add to baking heat heater H food baking. Open the shell, for safety reasons overhaul, pull out the high voltage transformer T1 primary connector, cut off the high voltage power supply circuit. Set baking state test machine, able to hear the sound of baking relay action, measuring H 220V voltage at both ends of the baking heater has thus confirmed, baking control circuit is working properly, the fault lies in the baking heater. The baking heater consists of two 110V/500W quartz heating tubes in series, in which a quartz heating tubes measured infinite resistance, the normal resistance of about 22Ω, indicating that the quartz heating tubes burn caused by the failure to put a good quartz heating tubes, the fault that is excluded.BTVservice manual download site