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该机装带后便自行卸带,其他功能均失效,检测整机各部分电源电压,发现IC_1(SVS866)微处理器电源电压高达12V左右,正常值为5V,进一步检查,发现稳压二极管ZD_1内部断路,失去稳压作用,更换ZD_1后电压恢复正常,放像机装带、卸带、快进、倒带均正常。但机器一加载就引起停机保护,指标灯闪烁,为此逐步检修。当检查到整流部分时发现机器一加载,整流输出电压(20V)略有下降,而交流16V却无变化。怀疑硅桥有问题,拆下一测,果然有一只二极管性能不良,
After loading, the machine unloads the tape and other functions fail. The power supply voltage of each part of the whole machine is detected. It is found that the power supply voltage of the IC_1 (SVS866) microprocessor is up to about 12V and the normal value is 5V. Upon further inspection, the voltage regulator diode ZD_1 Internal circuit, loss of voltage regulator function, replace the ZD_1 voltage back to normal, put the tape player, unloading, fast forward, rewind are normal. However, the machine caused a shutdown load protection, indicator light flashes, for this overhaul. When checking the rectification section, it was found that when the machine was loaded, the rectified output voltage (20V) dropped slightly while the AC 16V remained unchanged. Suspected silicon bridge problems, remove a test, and sure enough there is a poor diode performance,