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820-00928 Overheating Around USB-C area

brunomotter

brunomotter

Member
Got this one here and it was not turning on. There was corrosion around U3900 area and some missing resistors there. I managed to get the board working again after placing missing components and cleaning up the area. Machine is working ok, except when I connect power to left USB-C port nearest the trackpad. When I connect power there, the area around Q3100 heats so much that cooler kicks in full blast and to the point even turning the machine off and area gets REALLY hot to touch, to the point of burning the finger. All other ports behave ok and no heating at all. Tried replacing USB-C port, replaced U3100, Q3100/Q3200, CC772, CB211, CC773, C3509/08/07 but still same issue. Any ideas?
 
2informaticos

2informaticos

Administrator
Staff member
Check with thermal cam what exactly gets hot there.
Compare diode mode readings between both channels of J3300; or compare with right connector, JB500.

Machine still works when connect power to that port?
 
brunomotter

brunomotter

Member
If I had a thermal cam I'd do it haha. Machine works with power connected to it and even charges battery normally, but turns itself off after some minutes due to overheating. Will need to compare diode between ports still...
 
brunomotter

brunomotter

Member
Now board is heating outside the case too on that specific port and I could trace what's heating. It's Q3100. I've replaced this twice and issue persists.
 
2informaticos

2informaticos

Administrator
Staff member
Maybe it is not correctly controlled by U3100.
Check their traces, replace U3100 again.
Compare Q3100/200 voltages, when MLB is powered on these ports.
 
brunomotter

brunomotter

Member
Yes, trace is good. I even removed again U3100 and Q3100 and measured resistance between PIN 9 of U3100 and PIN 4 of Q3100 and it's less than 1OHM resistance.
 
2informaticos

2informaticos

Administrator
Staff member
If Q3100 is correctly driven, shouldn't get hot; should have less than 10 miliohm I/O internal ressistance.
It must get at least 5V more on each Gate pin than corresponding Source pin.
Check that difference comparing with the other MOSFETs.
 
brunomotter

brunomotter

Member
Well. I got some more boards here from the same model and ALL of them have the same heating behavior when charging. And I noticed that it's on all ports. I think this is an expected behavior and not a problem.
 
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