820-00239 5v 0amps

[JdYoda]

Hello!

Can not get 20 volts on this board. Customer says that for last 2 days charging was unstable, then laptop just turned off

Now there is 3 CD3215 in the loop, UB400 stable
Board is clean, no corrosion, no oxidation
Found blown resistor RB036 ( replaced)
Already changed UB400 ( 2 times, with known-good chip), UB300 (just for case), QB400 and UB090 (from same donor board) - still 5v
PP3V3_G3H is present
All CD3215 except UB400 has 1.1 LDOs
Compared all LDOs in diode mode with other chips-it is similar (0.470 - 0.500)
Checked all resistors around UB400 and UB300 - values matching schematic
Checked all traces under UB400 - no problem there.

What else might cause this issue?

 

[2informaticos]

You should put back UB090; if the new one is not from the same donor board model.

Something wrong near UB400.
Compare diode mode readings with U3200, on all surrounding components; not only the LDOs.
Check RB305/405.

 

[JdYoda]

Found the problem near UB300. After i removed metal shield around U9290 i saw that pins of RB305 and RB303 doesn't looks good. After resoldering all of the resistors in this row mac turns on. Thank you very much