Hi all,
I've got a couple of laptop motherboards with shorts, but I don't have a bench power supply yet.
The one I'm working on right now is somewhat disposable.
It's a Compaq CQ58 (AMD based) (lack of actual schematics) - I can get a brand new board for £19.99 from eBay at the moment and even then it might just all go in the bin.
So there was a crispy 4435 mosfet (damage seemed mainly on the source and gate side rather than drain) right next to the input for the power DC jack. I pulled another from a dead board - tested OK and installed it. The replacement part starts to get warm rather quickly. There seems to be a lack of protection in the circuit or charger? The output from the charger is about 19v 3a.
I have a short in the circuit somewhere, evident by quite a few of the surface mount capacitors showing dead shorted (including some on what I believe to be the chipset or GPU). My current method of pulling off each shorted cap from the board and testing to see if the short disappears (or the removed cap is shorted) is tedious to say the least and I'm not particularly skilled at it...
If I improvised with a modem/hard drive power supply rated at 12v 1-2amps and connected it to the usual 19v input, would this work for helping me to find a short without doing damage (especially to the mosfet which already fried) or would it be the wrong approach?
Thanks for any advice!
I've got a couple of laptop motherboards with shorts, but I don't have a bench power supply yet.
The one I'm working on right now is somewhat disposable.
It's a Compaq CQ58 (AMD based) (lack of actual schematics) - I can get a brand new board for £19.99 from eBay at the moment and even then it might just all go in the bin.
So there was a crispy 4435 mosfet (damage seemed mainly on the source and gate side rather than drain) right next to the input for the power DC jack. I pulled another from a dead board - tested OK and installed it. The replacement part starts to get warm rather quickly. There seems to be a lack of protection in the circuit or charger? The output from the charger is about 19v 3a.
I have a short in the circuit somewhere, evident by quite a few of the surface mount capacitors showing dead shorted (including some on what I believe to be the chipset or GPU). My current method of pulling off each shorted cap from the board and testing to see if the short disappears (or the removed cap is shorted) is tedious to say the least and I'm not particularly skilled at it...
If I improvised with a modem/hard drive power supply rated at 12v 1-2amps and connected it to the usual 19v input, would this work for helping me to find a short without doing damage (especially to the mosfet which already fried) or would it be the wrong approach?
Thanks for any advice!
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