Abstract: Provided is a heater power control circuit which switches on/off a voltage signal supplied from a direct-current power source to control a power of a heater by controlling a voltage applied to the heater. The heater power control circuit includes a voltage smoothing circuit that is disposed between the heater and a switching circuit which switches on/off a voltage supplied from the direct-current power source. The voltage smoothing circuit converts the voltage into an analog voltage signal by smoothing a voltage signal obtained by switching on/off the voltage.

Abstract: A method of detecting an abnormality in a burn-in apparatus, which brings a heater and a temperature sensor into contact with various devices under test during a burn-in test and controls power consumption of the heater to adjust levels of temperature of the devices under test, wherein the temperature sensor detects temperature of a temperature control block in which the heater and the temperature sensor are arranged and with which a cooling liquid is in contact while the devices under test are not in contact with the heater and the temperature sensor, and the temperature sensor is diagnosed to be normal or not based on a result of detection.

Abstract: A method of monitoring a burn-in apparatus, which brings a heater and a temperature sensor into contact with various devices under test during a burn-in test and controls power consumption of the heater to adjust levels of temperature of the devices under test, wherein the temperature sensor detects temperature of a temperature control block in which the heater and the temperature sensor are arranged and with which a cooling liquid is in contact while the devices under test are not in contact with the heater and the temperature sensor, and the temperature sensor is diagnosed to be normal or not based on a result of detection.

Abstract: A system including a cellular phone or a telephone card having, pre-registered therein, the identification number of a connection telephone company and a user ID, a store processing terminal unit handling it, a point-of-sale POS terminal, and a management host computer of the telephone company, wherein these are connected through a communication line. A merchandise information of the cellular phone that is transacted, etc., is sent to, and stored in, the host computer. When a call is made using the cellular phone, or the like, the host computer carries out reduction processing of a prepaid telephone charge depending upon a call rate on the basis of the stored merchandise information of the cellular phone, or the like. When the cellular phone or the telephone card is used, telephone charges can be paid in a store handling such a cellular phone, or the like.