820-01958: Not powering up.

Have this board that's not power up, not sure if i've successfully isolated it but compared to the 820-01521 version, on U7650 after plugging in the power and then removing it, pin 4 (P5VG3S_EN_DLY) has a resistance of 93ohms. On a good board, performing the same test, pin 4 remains at 47k. I've replaced U7650 and R7611 (from 820-01521 sch.) but still getting the same result. Would be safe to say the issue is with U7610 and if so, can i pull it and jumper pins 1 and 4 to confirm this without damaging the board?
 

2informaticos

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Allow 10-15s to measure diode mode, or ohms cale, after power is removed.

Can you post some basic voltages and signals?
We have posted on the forum the Power On Sequence Diagram for 01598 board, which serves for all T2 machines.
 
Diode measurement is 0.61 before power
15sec after power removed, diode measurement 0.14 and slow starts to climb as times goes on. At 3min its at .34.

Here are some of the voltage readings. a bit tricky finding the test points as there are a lot of differences between the 820-01958 and 01521. 20v is being supplied

PP3V3_G3H - 3.28
PP5V_G3S - 0.019
PPVIN_G3H_P5VG3S - 12.3
PPVIN_G3H_P3V3G3H - 12.3
PPBUS_G3H - 12.3
PPBUS_HS_CPU - 12.3

Also i can't seem to find the power on sequence you were referring to.
 
Last edited:
so more measurements

PPVDDCPU_AWAKE - 0.75
PMU_SYS_ALIVE - 1.8
PMU_VDDMAIN_EN - 0
P3V3MAIN_PGOOD - 0 (resistance measurement also shows 100ohms to ground and slowly climbing until reaching mega ohm range)

PP3V3_G3H_RTC 3.28

Anything else to check.
 
Guess i should have checked that first. Still getting used to these T2 style system. Anyway, looks like it was stock in DFU mode. once i ran the revive action, it brought it back to life. It's now going through the install process.

Thanks a lot for the assist.
 
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