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贵刊96年第9期刊出的《简易维修电话用电源》一文中用36V、50Hz的交流信号代替交换机输出90V_(P-P)、25Hz的铃流信号,我认为欠妥。36V交流信号,峰—峰值为2~(1/2)×36≈51V_(P-P)加在正常电话二端确有振铃声,但在维修实践中常因电话内部绝缘性能差引起故障,表现为铃流到来时振铃只响一声或来不及振铃就被击穿(如HA868(Ⅲ)P/TD电话进线端电路板或免提开关SW1绝缘性能差等)。本人曾使用电话检修仪检修此类故障,发现用检修仪测试振铃正常,但一接到市话线上就出现故障。用示波器观察检修仪的铃流电压仅65V_(P-P),可见
The 96th, 50Hz AC signal replaced by the switch output 90V_ (P-P), 25Hz ring current signal published in the ninth issue of the 96th issue of “easy maintenance telephone power supply” article, I think defective. 36V AC signal, the peak - the peak 2 ~ (1/2) × 36≈51V_ (PP) plus the ringing sound at the two ends of the normal phone, but in practice, often due to poor insulation performance of the phone caused by failure, the performance of the bell When the flow arrives, the ringing will break down only once or after the ring (for example, the HA868 (Ⅲ) P / TD telephone incoming circuit board or the hands-free switch SW1 has poor insulation performance, etc.). I had used a telephone repair instrument to repair such a fault and found that it was normal to use a tester to test the ringing, but a fault was found on the local telephone line. Observed with oscilloscope surgeon bell current voltage is only 65V_ (P-P), can be seen