M.Joshi
Member
Hello,
I am trying to repair a Dell laptop PSU which is just making a high pitched pulsed whistle. I went to probe the voltage on one of the power FETs and accientally blew it together with an adjacent resistor! I'm hoping that's all that has blown?
The FET is an ST P10NK60ZFP and the resistor looks like a low value 1W resistor? I have attached photos of the PSU, damaged resistor and adjacent intact resistor:
PSU information label:
![Dell LA90PS0-00.jpg Dell LA90PS0-00.jpg](https://www.electro-tech-online.com/data/attachments/93/93698-1b2a89314e9aedc8fad86ffa13362d2e.jpg)
Top view:
![LA90PS0-00 top view.jpg LA90PS0-00 top view.jpg](https://www.electro-tech-online.com/data/attachments/93/93699-9567815ea136fa7280625f079be8e3ae.jpg)
Rear view:
![LA90PS0-00 rear view.jpg LA90PS0-00 rear view.jpg](https://www.electro-tech-online.com/data/attachments/93/93700-51ab40549a0b097e2ac6d3e33f723b43.jpg)
Close up of burnt area:
![Close up of burnt area.jpg Close up of burnt area.jpg](https://www.electro-tech-online.com/data/attachments/93/93701-9324ecef6698f54db317386c55b5eb59.jpg)
Intact resistor - photo 1:
![Intact resistor 1.jpg Intact resistor 1.jpg](https://www.electro-tech-online.com/data/attachments/93/93702-cdfde0302a2deb552e36f002db018c42.jpg)
Intact resistor - photo 2:
![Intact resistor 2.jpg Intact resistor 2.jpg](https://www.electro-tech-online.com/data/attachments/93/93703-adf1b4a5af947e1bc48d32c89284befa.jpg)
Intact resistor - photo 3:
![Intact resistor 3.jpg Intact resistor 3.jpg](https://www.electro-tech-online.com/data/attachments/93/93704-8d3307b05d3354fba880ef516d58ae32.jpg)
Damaged resistor:
![Damaged resistor.jpg Damaged resistor.jpg](https://www.electro-tech-online.com/data/attachments/93/93705-d8ef0566a9f7eeb589b3f0df6088eb8d.jpg)
Does anyone know where I can find a schematic for this PSU? I have found one for a similar PA-12 family PSU but I can't work out what the damaged resistor value might be?
I think I have identified the fault with the PSU with the help of a post on another website which points to a short on the output DC cable. There does appear to be a short on the +/- pins on the output. Just wish I checked this first!
I am trying to repair a Dell laptop PSU which is just making a high pitched pulsed whistle. I went to probe the voltage on one of the power FETs and accientally blew it together with an adjacent resistor! I'm hoping that's all that has blown?
The FET is an ST P10NK60ZFP and the resistor looks like a low value 1W resistor? I have attached photos of the PSU, damaged resistor and adjacent intact resistor:
PSU information label:
![Dell LA90PS0-00.jpg Dell LA90PS0-00.jpg](https://www.electro-tech-online.com/data/attachments/93/93698-1b2a89314e9aedc8fad86ffa13362d2e.jpg)
Top view:
![LA90PS0-00 top view.jpg LA90PS0-00 top view.jpg](https://www.electro-tech-online.com/data/attachments/93/93699-9567815ea136fa7280625f079be8e3ae.jpg)
Rear view:
![LA90PS0-00 rear view.jpg LA90PS0-00 rear view.jpg](https://www.electro-tech-online.com/data/attachments/93/93700-51ab40549a0b097e2ac6d3e33f723b43.jpg)
Close up of burnt area:
![Close up of burnt area.jpg Close up of burnt area.jpg](https://www.electro-tech-online.com/data/attachments/93/93701-9324ecef6698f54db317386c55b5eb59.jpg)
Intact resistor - photo 1:
![Intact resistor 1.jpg Intact resistor 1.jpg](https://www.electro-tech-online.com/data/attachments/93/93702-cdfde0302a2deb552e36f002db018c42.jpg)
Intact resistor - photo 2:
![Intact resistor 2.jpg Intact resistor 2.jpg](https://www.electro-tech-online.com/data/attachments/93/93703-adf1b4a5af947e1bc48d32c89284befa.jpg)
Intact resistor - photo 3:
![Intact resistor 3.jpg Intact resistor 3.jpg](https://www.electro-tech-online.com/data/attachments/93/93704-8d3307b05d3354fba880ef516d58ae32.jpg)
Damaged resistor:
![Damaged resistor.jpg Damaged resistor.jpg](https://www.electro-tech-online.com/data/attachments/93/93705-d8ef0566a9f7eeb589b3f0df6088eb8d.jpg)
Does anyone know where I can find a schematic for this PSU? I have found one for a similar PA-12 family PSU but I can't work out what the damaged resistor value might be?
I think I have identified the fault with the PSU with the help of a post on another website which points to a short on the output DC cable. There does appear to be a short on the +/- pins on the output. Just wish I checked this first!
Last edited: