电磁炉维修损坏二极管三极管案例

  1:用耐压仪测:把被测三圾管8050,C极与万用表DC50V档正极相接,E极与万用表负极相接,摇测,若读数在+30V_--+50V范囲內为正常,<+30V为失效,>50V为开路损坏.(PNP型管检测如8550,只将C极,E极对调后即可,其它检测同NPN管).  2:用万用表检测:万用表RX1K档测8050,C,E极正反均为无穷大,黑笔接B极,红笔 接C极或E极均为8K左右,反之均为无穷大.测8550时,只将红黑笔对调即可,数据和上面相同.以上结果为正常. 八:判断晶振的好坏:  用万用表RX10K档,测晶振两端阻值,若为无穷大,说明晶振无短路或漏电;

再将试电笔插入市电插孔內,用手指捏住晶振一脚,将另一引脚碰触试电笔顶端的金属部分,若试电笔中氖泡发红,说明晶振是好的;若氖泡不亮,晶振损坏.  九:三端稳压器AN7805的检测:  用耐压仪测,把被测三端稳压器LM7805输入端接万用表DC10V档正极,LM7805输出端也接万用表DC10V档正圾,LM7805外壳与万用表负极相接,进行摇测,检测电压+5V为正常;若低于+5V为击穿,当0V时,则三端稳压器LM7805开路损坏.     电磁炉故障检测与排除 一:故障代码表  故障               代码              声音                                                             备   注  无锅                E1                每隔3秒一声短                                             5秒后进入待机状态 电压过低         E2               每隔3秒一声短                                                 5秒后进入待机状态 电压过高         E3               每隔3秒一声短                                                   5秒后进入待机状态  干烧保护         E4                每隔3秒一声短                                                   5 秒后进入待机状态 IGBT超温        E5                5秒后进入待玑状态                                           5秒后进入待机状态 TH1(锅底RT)   E6                                                                                             不能开机    开路 TH2开路  (IGBT,RT)      E7                                                                                                 不能开机 电流过大       E0                                                                                                     不能开机    定时结束                                                                                                               立即关机 保温状态                                                                                                                  间歇工作 说明:代码只适用于数显机型,非数显型只有声音报知及指示灯. 二:主板检测   标准     由于电磁炉工作时,主回路工作在高压大电流状态中,所以对电路检查时必须将线盘(L1)断开不接,否则极容易在测试时因仪器接入而改变电路参数造成机器损坏.接上线盘试机前,应根据2.1<<主板检测表>>对主板各点作测试合格后才进行试机. 2.1:主板检测表  (一);待机(静态)检测表(不接线盘,接入电源后,不按任何键)     步 骤           测   试   点                  标    准                  备    注                                 不 合 格 对 策    1                  通电                             发出"B"一声                                                        按2.2第(1)项査     2                 CN7                              +300V                   电源AC220V时                     按2.2第(2)项査     3                 +18V                           +18V                                                                   按2.2第(3)项査      4                  +5V                              +5V                                                                   按2.2第(4)项査      5                 Q3G极(风扇管)             <0.5V                                                                 按2.2第6 5)项査       6                  IGBTG极                      <0.12V                                                               按2.2第(6)项査     7                  B点(`VAC检测)            + 2.0V                      确认电源220V时                   按2.2第(7)项查       8                V3(同步电路左侧)         + 1.72V                    确认电源220V时                按2.2笫(8)项查