820-4924-a cycling power

[Mister Motherboard]

I have a 820-4924 that came in with a blown f7005
I replaced the fuse and now have a green light that flashes on once every few seconds.
Power is cycling at f7005 so power is cycling everywhere else, something is sending a signal to shut down power supply.
I have checked for shorts everywhere, none found.
No sign of liquid damage, all indicators are normal.
If I use my bench power supply and apply 19v at f7005 while the mac power supply is plugged in, the board will power on and run normally.
While running I can find nothing abnormally hot.
Tried other power cords so that isn't it.
Anyone run into this before?
Thanks!

 

[2informaticos]

"bench power supply and apply 19v at f7005 while the mac power supply is plugged in "
Do you mean connecting both charger and lab power supply at same time???
Please, do NOT say that...

For testing, use 85W charger to connect ONLY lab power supply.
Be aware, turn it on after cable is connected to the board.

Q7180 and D7010 are the first suspects there; change Q7180 first.

 

[Mister Motherboard]

"bench power supply and apply 19v at f7005 while the mac power supply is plugged in "
Do you mean connecting both charger and lab power supply at same time???
Please, do NOT say that...

For testing, use 85W charger to connect ONLY lab power supply.
Be aware, turn it on after cable is connected to the board.

Q7180 and D7010 are the first suspects there; change Q7180 first.

Yep, been doing that on mac boards since 2006 on issues like this, never had a problem, and has always been a helpful diagnostic tool. I make sure the voltage matches precisely and put a low current limit on the bench supply in case something goes wrong it wont burn anything. I am aware of ground loop risk. Anyway, I'll check that transistor and diode.
Thanks for the advice.

 

[Mister Motherboard]

"bench power supply and apply 19v at f7005 while the mac power supply is plugged in "
Do you mean connecting both charger and lab power supply at same time???
Please, do NOT say that...

For testing, use 85W charger to connect ONLY lab power supply.
Be aware, turn it on after cable is connected to the board.

Q7180 and D7010 are the first suspects there; change Q7180 first.

Q7180 it was. Now that I flipped it over I can see it was leaking.
Thanks!

 

[2informaticos]

Do NOT apply dual power again.
In fact lab power supply is the only working in case like that.
Please, use the logic...