820-00840-A PP3V3_G3H dragged down to 2.1V

[Jenzo]

Hi,

This board has no signs of liquid damage.

Charger was stuck at 5V 0amp. I had no PP3V3_G3H, found C7078 was bad, replaced it and now I have PP3V3_G3H again. Only it's stuck around 2.1V.

I removed R6999 (and replaced, just to be sure), and I have 3.3V on pin 1, so there shouldn't be an issue with my U6990 I think? I figured it was U7000 (ISL9232), replaced it, but the problem remains the same. I do have 5V 0.05a on the charger at this point. So now I'm running in circles, I can't seem to figure out why I have this drop on PP3V3_G3H.

Diode mode reading (red on ground) on PP3V3_G3H is 0.384. This is with R6999 back on the board.

PPBUS_G3H is at 0.2V if that is any hint. Thank you in advance!

 

[2informaticos]

First of all, welcome to the forum!

If you get 3V at C6995 removing R6999, then the problem is on the right side of R6999.
Something consumes more current than expected.

Check diode mode to ground on LDO rails of both CD3215 chips.
Take a look at USB redriver chip, PI3USB32224.
It doesn't appear in the schematic, nor boardview; as many times explained on the forum.

 

[Jenzo]

Thank you!

PP3V3_UPC_XA_LDO 0.506
PP1V8_UPC_XA_LDOD 0.484
PP1V8_UPC_XA_LDOA 0.524
PP1V1_UPC_XA_LDO_BMC 0.519

PP3V3_UPC_XB_LDO 0.505
PP1V8_UPC_XB_LDOD 0.487
PP1V8_UPC_XB_LDOA 0.526
PP1V1_UPC_XB_LDO_BMC 0.521

Forgot to mention I temporarily removed the redriver chip, sorry.

 

[2informaticos]

Now post voltage for these lines.
Be aware, LDO_BMC should only appear on the powered port.

 

[Jenzo]

PP3V3_UPC_XA_LDO 2.18v
PP1V8_UPC_XA_LDOD 0v
PP1V8_UPC_XA_LDOA 0v
PP1V1_UPC_XA_LDO_BMC 0v

PP3V3_UPC_XB_LDO 3.27v
PP1V8_UPC_XB_LDOD 1.79v
PP1V8_UPC_XB_LDOA 1.8v
PP1V1_UPC_XB_LDO_BMC 0v

This is measured using one of the usb ports, should I do it as well with the second usb port?

A second question, don't know if it is relevant to this because I lost track of how I got there, but while checking around a bit I noticed SMC_AUX_OK, and SMC_BC_ACOK are short to ground. I've noticed it is connected to pin 28 of the ISL9239 I replaced, right next to 2 ground pins. Should I assume I did not solder it properly?

 

[Jenzo]

Yep, messed up the ISL9239, removed it and the short was gone. I'm afraid I'm out of ISL9237's, ordered one, should have it in 2 days. Am I correct in assuming this is the cause of the problem?

 

[2informaticos]

You must replace U7000 correctly.
Bad solders, or accidental short will make you waste the time.

BTW, check CD3215 chip voltage when charger is connected to corresponding port.

 

[Jenzo]

Sorry I didn't get back to you on the CD3251 voltage.

But, I replaced the U7000. After that, D6905 turned out to be bad as well, replaced it, and have a fully working board now!

Thank you for the assistance!