如何運(yùn)用8d解決問題-資料下載頁
2025-03-25 00:28本頁面
【正文】 isted below in the XXX circuit are damaged: Part Spec. DescriptionD5,D6,D7,D8XX A/XX V Rectifier Diode Circuit Schematic Fishbone Diagram Experiments to Reproduce the Failure D5D8 temperature measurementCondition: 1) The unit operates at ambient temperature。 2) Connecting a xx Ohm resistor between positive and negative terminals of the battery to stimulate very low battery voltage.Result: Case temperature of the diodes stabilizes at about 60 degree Celsius which is much lower than the maximum rating with adequate margin. Battery short circuitCondition: Short circuit the battery and measure the current passes through D5D8 with current probe.Result: The current is zero Low battery voltageThe unit operates with the DC power provided by a xx V(which is much lower than the nominal xx V) battery. Measure the current passes through D5D8 and no overcurrent is found. Overcurrent through D5D8 when power on with nominal I/P AC voltageThe DC power is provided by a battery with nominal voltage. Measure the current passes through D5D8 with current probe at the moment when power on the unit with nominal AC input voltage. Overcurrent is found. High input AC voltage and low battery voltage when power onConnect a xx Ohm resistor between positive and negative terminals of the battery to stimulate very low battery voltage. Measure the current passes through D5D8 with current probe at the moment when power on the unit with xx AC. The current reaches xx A which is much larger than the maximum rating xx A and that can easily destroy the diodes. ConclusionBased on the above experiments, the root cause is that at the moment when power on the unit, especially with low battery voltage and high input AC voltage, outofspec current through the diodes presents.4. Containment Plan Fix the unit, replace damaged ponents5. Permanent C/A Plan1) Change Cxx from xx μF/xx V electrolytic capacitor to xx uF/xx V XCap to reduce the current through the rectifier when power on the unit.2) Use an integrated rectifier to replace D5D8.3) RD release ECR for customer approval of the above engineering changes after the effectiveness is verified.4) RD release ECN to validate the changes after the ECR is approved.6. Verify the effectiveness of C/A 1) Measure the current through the integrated rectifier at the same condition of , no overcurrent is found. 2) Perform power cycling on 10 engineering changed units under the condition described at for 48 hours, no failure was found.7. Prevent RecurrenceUpdate the Standard Circuit Design Procedure (Doc. : xxxxxxxx). Add an item in Section 11 – xx Circuit Design Standard, to require: 1) using XCap rather than electrolytic capacitor parallel with the rectifier, and, 2) using integrated rectifier rather than individual diodes in xx circuit design. 8. Congratulate the TeamThe ECR has been sent to XXX (the customer name) for approval on Sep. 25. and the updated procedure will be released formally by DCC immediately when receive the approval. Thanks for the excellent work of the team.
環(huán)評公示相關(guān)推薦
鄂ICP備17016276號-1