Hello!
I am still learning on laptop repairs and I am currently working on the above mentioned device.
Currently the laptop is dead (no power on). The device takes 2-3 mA when 20v are injected onto the charging plug.
Main power rail is present (20v), but no other power rail is present, including the 3v and 5v. I noticed that when no power is connected the 3v and 5v coils have large (normal) resistence to ground, but when I plug the power, both are being shorted to ground.
I wonder is that an expected behavior or there is an outer protection activated.
What I tried so far without result:
replaced the 3v and 5v dual channel buck converter.
replaced the grounding mosfets at the 3v and 5v rails
Here is the schematics (pcb model DA0NJFMBAD0) :
When I inject 2-3 volts on the 5v coil, i see that (with termal camera) that PQ1003 mosfet is leaking to ground. When this vilatage is injected on the 3v coil, no leakage appears.
When I measure the mosfet only, no issue is observed.
The only concerns I have about by work so far is that the components were taken from spare boards and there is a sligh chance they are not working, but I find it would be really unluccky to repeat the very same problem, when most of the active components were replaced. And also - the PC1015 cap broke during cleaning the board with toothbrush ( I think it was crack soldered), but I am undable to solder it back due to very small size and bad positioning.
Any advice would be appreciated, thanks!
I am still learning on laptop repairs and I am currently working on the above mentioned device.
Currently the laptop is dead (no power on). The device takes 2-3 mA when 20v are injected onto the charging plug.
Main power rail is present (20v), but no other power rail is present, including the 3v and 5v. I noticed that when no power is connected the 3v and 5v coils have large (normal) resistence to ground, but when I plug the power, both are being shorted to ground.
I wonder is that an expected behavior or there is an outer protection activated.
What I tried so far without result:
replaced the 3v and 5v dual channel buck converter.
replaced the grounding mosfets at the 3v and 5v rails
Here is the schematics (pcb model DA0NJFMBAD0) :
When I inject 2-3 volts on the 5v coil, i see that (with termal camera) that PQ1003 mosfet is leaking to ground. When this vilatage is injected on the 3v coil, no leakage appears.
When I measure the mosfet only, no issue is observed.
The only concerns I have about by work so far is that the components were taken from spare boards and there is a sligh chance they are not working, but I find it would be really unluccky to repeat the very same problem, when most of the active components were replaced. And also - the PC1015 cap broke during cleaning the board with toothbrush ( I think it was crack soldered), but I am undable to solder it back due to very small size and bad positioning.
Any advice would be appreciated, thanks!
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