Sharp R-21JVF Service Manual - Page 25

PRECAUTIONS FOR USING LEAD-FREE SOLDER R-21HT-F R-21JV-F 1. Employing lead-free solder The "Main PWB" of this model employs lead-free solder. This is indicated by the "LF" symbol printed on the PWB and in the service manual. The suffix letter indicates the alloy type of the solder. Example: Sn-Ag-Cu Indicates lead-free solder of tin, silver and copper. 2. Using lead-free wire solder When repairing a PWB with the "LF" symbol, only lead-free solder should be used. (Using normal tin/lead alloy solder may result in cold soldered joints and damage to printed patterns.) As the melting point of lead-free solder is approximately 40˚C higher than tin/lead alloy solder, it is recommend that a dedicated bit is used, and that the iron temperature is adjusted accordingly. 3. Soldering As the melting point of lead-free solder (Sn-Ag-Cu) is higher and has poorer wettability, (flow), to prevent damage to the land of the PWB, extreme care should be taken not to leave the bit in contact with the PWB for an extended period of time. Remove the bit as soon as a good flow is achieved. The high content of tin in lead free solder will cause premature corrosion of the bit. To reduce wear on the bit, reduce the temperature or turn off the iron when it is not required. Leaving different types of solder on the bit will cause contamination of the different alloys, which will alter their characteristics, making good soldering more difficult. It will be necessary to clean and replace bits more often when using lead-free solder. To reduce bit wear, care should be taken to clean the bit thoroughly after each use. PROCEDURE FOR CHECKING/CLEARING SERVICE COUNTS OF MICROWAVE OVEN The following procedure enables the servicer to obtain the total using times (cook cycles) since the microwave oven is purchased and the total operation time (hours) since the microwave oven is purchased. The maximum capacity of the total using is 999,999 times, and the maximum capacity of total operation time is 999,999 hours. 1) Practice for checking total using times (Ex. 345678 times). ... Flashing / ... 0.1sec BUZZER PAD (Door close) CHECK CHECK #2 SIGNAL SIGNAL DOUBLE QUANTITY DISPLAY . . . #1 82 68 (user total count) INDICATOR PHONE CHECK No. CHECK 34 56 (service total count upper figure) 3456XX 1 (No 1) 1 No. (after 1 sec.) 34 56 (service total count upper figure) 2 (No 2) 2 No. (after 1 sec.) CHECK 78 (service total count lower figure) . 2) Practice for checking total operation time (Ex. 4567 hours). PAD (Door close) CHECK CHECK #2 SIGNAL SIGNAL DOUBLE QUANTITY ... Flashing / DISPLAY . . . #1 82 68 (user total count) ... 0.1sec BUZZER INDICATOR PHONE CHECK No. CHECK 34 56 (service total count upper figure) 3456XX 9 (No 9) 9 No. (after 1 sec.) 45 (Total operation time upper figure) 0 (No 0) 0 No. (after 1 sec.) CHECK 67 (Total operation time lower figure) . 23