820-00840 5v on both port

[Yoel Ren]

Hi, this machine came in dead, with 5v on both port, consuming about 30-40ma

pp3v3_g3h is fine
ppbus not shorted
smc_reset_l 3.4v
buf_smc_reset_l 3.4v


Both of the cd3215 missing pp1v1 ldo, cd3215 has been replaced with KNOWN GOOD chip, still the same.
any pointer ?

 

[2informaticos]

Any history about how the fault appeard?
What about SMC_RST_IN?

Check SMC_USBC_INT_L signal.

 

[Yoel Ren]

clean board, customer as usual just say nothing happen it just dead some day..
smc_rst_in 0v
smc_usbc_int_l 3.3v

have tried removing the redriver chip too, but still same problem

 

[Yoel Ren]

does this machine need u2800 to switch to 20v ?

 

[2informaticos]

Machine can work without U2800.
But will loss USB activity once macOS is loaded.

Post U7000 basic voltages; P_IN, AUX_DET, VDDA/P, AUX_OK, A/BMON.

 

[Yoel Ren]

p_in 5.1v
aux_det 1.05v
tba_vdda 5.1v
tba_vddp 5.1v
aux_ok 3.4v
amon 0v
bmon 0v

 

[2informaticos]

"ppbus not shorted"
Can we give real diode mode readings?
Check in both directions, please.

Remove F7000 and check C7050 voltage.

 

[Yoel Ren]

diode mode 0.430 on both side of F7000.
with f7000 removed, c7050 voltage is 0.2v ..

 

[Yoel Ren]

resistance between pin 1 and 2 of c7020 and c7023 is 2 ohm respectively, if that matters

 

[Yoel Ren]

found d3402 blown. but the line is not shorted.
found usbc_xb_d2r_p shorted, from u2800.
pulled u2800, and mac boot with 20v,
just need to pull another chip and install it to the mac, thank you so muchh for the pointer