⑴ Voltage Adjustment Method: Adjust the AC input voltage using an AC voltage regulator, monitor the B+ output voltage to maintain it slightly above the normal level. (Because if the sampling is normal, the negative feedback voltage stabilization loop should take control at this point.) Then measure the b, e, and c voltages of the three tubes at each stage of the pulse width adjustment circuit, the voltage drop between the ① and ② pins of the optocoupler, to see if they correspond to or follow the same trend as the voltage stabilization principle. If a point is reached where the measured value contradicts the expected value according to the voltage stabilization principle, it indicates a fault at that stage being measured, preventing the correct transmission of voltage stabilization information and leading to stabilization failure. It is necessary to inspect the relevant components one by one.
⑵ The segmentation method (suitable for direct sampling power supply) uses the optocoupler in the voltage regulation loop as a dividing point to segment the circuit and determine the fault range. Short-circuit the ③ and ④ terminals of the optocoupler and observe the change in B+. · A significant drop or cessation of B+ output indicates that the heat sink section is normal. The fault is in the B+ sampling circuit and the optocoupler. · If there is no noticeable change or no change at all, it suggests a fault in the heat sink section. A detailed check of the pulse width adjustment circuit in this section is required. Focus on checking the formation circuit of the pulse adjustment circuit's working voltage, such as filter capacitors and rectifier tubes, and use the replacement method. Also, check the replacement of the adjusting tubes and related components, and inspect for any open circuits in the copper foil. Aviation ground power 2, 36V aviation power supply 1, 400HZ frequency conversion power supply 7, 115/200V power supply 2, 27V DC power supply 5, 400HZ power supply 12, aviation power supply
