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820-00244: Not Powering up, PPVBUS_LIO - 0v

M

macRepairAmb

Member
Have another 00244 logic board, except this one isn't showing any sign of life. Also no sign of liquid damage.

PPVBUS_LIO - 0v.

I've compared resistance at F3050 with a known good board and it checks out. Any suggestions as to where to start with this type of failure?
 
J

JohnB8812

New member
CPU getting hot on this one too? If no, check if you have 5 or 20 volts on DC in first as well as what voltage you get on PPBUS_G3H
 
M

macRepairAmb

Member
PPVBUS_LIO is the main dc line from j9600. Also ppbus_g3h is also 0V.

PPVBUS_LIO does initially spike to almost 1v then drops to 0v when the charger is first plugged in.
 
2informaticos

2informaticos

Administrator
Staff member
Check resistance to ground (diode mode) on PPBUS_G3H and all power rails of U3100.
Also test the same at F7040 and L6995.
 
M

macRepairAmb

Member
PPBUS_G3H - 0.02v

Diode mode check of all power rails of U3100 and PPBUS_G3H, F7040 and L6995 comparable to a know good board. There's about .020v difference between boards on some of the readings.

While checking around, don't know if this means anything, but TPA508SMC_DEV_SUPPLY_L has about 2.5v.
 
2informaticos

2informaticos

Administrator
Staff member
"PPBUS_G3H - 0.02v"
Is that diode mode, or voltage reading?
Don't post end "V" for diode mode readings...
 
2informaticos

2informaticos

Administrator
Staff member
Charger gets protected, so no voltage apllied to board.
There is no reason to check voltages on the board; just diode mode...
 
M

macRepairAmb

Member
Value to the left is with positive multimeter probe to ground pad. Value to the right is with multimeter ground probe to ground pad.


PPBUS_G3H - 0.461/OL

PPVBUS_LIO - 0.592/OL

PP1V8_SUS - 0.424/1.40

PP3V3_UPC_VIN - 0.586/1.536

PP5V_S4 - 0.3172/1.9

PP3V3_S4 - 0.4831/1.5

PP3V3_UPC_XA_LDO - 0.5281/1.6

PPDCIN_G3H - 0.5787/OL

P1V2S5SW_HSMUX_EN - 0.77/1.44

PP1V8D_UPC_XA_LDO - 0.491/1.4
 
2informaticos

2informaticos

Administrator
Staff member
There is no short, nor even low value on any rail.
Check for continuity between F3050 and USB-C connector; should be 4 pins, on the charger side.
If OK, change U3100.
 
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