820-2936 no PPBUS_G3H

[BMarden]

I have PPDCIN_G3H, I have checked and have no shorts on any S5 rails, I have expected voltages around Q7085 but dead around Q7080. I have PP5V1_CHGR_VDD (5.1) and SMC_BC_ACOK is 2.4V and CHGR_BOOT_R is 4.77V. Have mV pulses on CHGR_UGATE.

There is no short on either side of L7030, current sense resistors on CHGR_CSO and CSi are as expected.

I have STG on CHGR_AMON that goes away when ISL is removed.

I am thinking bad ISL but don't have one on hand to swap, any others areas I can check to confirm while I wait for ISL?

Thanks
Bruce

 

[arghhh]

You have no green light. First, PP3V42_G3H present on U6901?

 

[BMarden]

Go Green Light, 3.5V on PP3V42_G3H and SMC_BC_ACOK_VCC, 2.4V on SMC_BC_ACOK, 3.5V on SYS_ONEWIRE and 16.4 on U6900 EXT (Pin 5)

 

[BMarden]

okay, I tried another DC in board and have green light now, but no change on PPBUS_G3H

 

[arghhh]

What's the voltage drop reading on it?

 

[dukefawks]

NEVER EVER pull a buck controller chip without removing the FETS. Without the chip in place there is nothing stopping the upper FET from passing full voltage to the regulated rail. In the PPBUS case nothing will fuck up, but on any other rail it will instantly kill everything on that rail.

 

[BMarden]

Good to know!

I did notice the short on AMON (Pin 9) of ISL went away when I pulled the ISL, can I consider that confirmation of bad ISL?

 

[dukefawks]

No idea, put a new one to be sure.