820-4924 no ppbus

It was a liquid damage board, the spill was around q7130 area.
i have cleaned and replaced all components, there is a short on system side of l7130, i haven't looked into yet as i was trying to get ppbus before hunting that short, so long story short i have replaced all components including isl6259 but i still get 15.80 volts instead of 12.56 on pin 1 of l7130.
resistance between pin 17/18 and 27/28 is 3 and 20 ohms.
i have compared values to working board and pin 21 of isl have around .8 volts on working board and non working have 0 on it.
what else should i check?
 

2informaticos

Administrator
Staff member
L7130 is part of buck controller.
You cannot get PPBUS_G3H if L7130 is lifted...
Pull out F7140 and check which side the short remains.
BTW, which is the exact value of that "short"?
Check if any big coil (secondary supply) has the same value, in respect with ground.

Be sure C7125 is in place, or you can risk to fry Q7130 again...
 

JohnB8812

New member
If you have 15 volts, I don't think you can possibly have a short...if you're worried on that removed F7140 and see if there is a low resistance reading on either side of the fuse. 16 volts means, Q7130 is shorted and always open. If this is the problem, replace Q7130, the ISL6259, and Q7155 all at the same time.
 
Top