A1708 820-00840-A 5V 400ma

[briancomputerdoctor]

I found a small amount of corrosion on the usb-c ports. I have cleaned them but the board won't request 20v. I cannot see any damage on the rest of the board. I'm getting 5v 400ma on both sockets. C3100, C3108, C3200, and C3208 are all giving around 3.4v R3000 and R3001 are also giving 3.4v. I'm not sure where to look next. I'm thinking that the socket may be shorted to ground.

 

[2informaticos]

First of all, welcome to the forum!

Check voltage and diode mode to ground at all CD3215 LDO rails.
Also check 3V3_G3H and PPBUS_G3H.

 

[briancomputerdoctor]

Thank you

U9911 is giving 3.4v on pin 6

DZ9927 is giving 13v on pin 2

 

[2informaticos]

Voltages look good.
Did you get these values with charger alone, no battery connected?

Don't forget about mentioned LDO rails...

 

[briancomputerdoctor]

Correct. The board is extracted.

I'm looking at the schematic. How do I identify the LDO rails?

 

[briancomputerdoctor]

U3100
pin 53 gives 3.38v and 170kΩ
pin 35 gives 1v and 200kΩ
pin 2 gives 1.8v and 360kΩ

 

[briancomputerdoctor]

U3200
pin 75 gives 1.79v and 100kΩ
pin 53 gives 3.3v and 165kΩ
pin 2 gives 1.79v

 

[briancomputerdoctor]

DZ9927 pin 1, R9928 pin 2, and Q9900 pin 2 are giving 0v. Is that significant?

 

[briancomputerdoctor]

On C7230 pin 1 I'm getting 0.3v

Should I be getting 13v?

 

[2informaticos]

Don't use boardview when specify MLB readings.
We need to look at schematic to understand what happens.
You can use the boardview to locate test pints, but PLEASE post schematic refference; signal name, or pin component.

CD3215 chip has 4 LDO rails.
You've specified 1V1 LDO for U3100, but not for U3200.
Also you've missed one 1V8 LDO for U3100.

Do you get 1V1 LDO on both chips?
It will apear only on the powered port!

Look at USB-C redriver chip if not burnt.
It doesn't appear on schematic, nor boardview; placed on the other board side, opposite to CD3215 chips.

 

[briancomputerdoctor]

Okay. I think I understand. I'll do that. Thank you.

PP1V8_UPC_XA_LDOA gives 1.78V

The readings I'm getting on diode mode fluctuate wildly. On that test pad I'm getting 1.5 MΩ and climbs. Some of the others went from their initial reading to the same thing. I'm not very familiar with this way of testing for a short to ground so I don't know if i'm doing the right thing.

 

[briancomputerdoctor]

PVP1V1_UPC_XB_LDO
_BMC gives 1.1v when I have power connected to one usb-c but no volts when connected to the other.

 

[briancomputerdoctor]

And now I just realised that
PVP1V1_UPC_XA_LDO
_BMC is the same. Gives the volts when connected to the other usb-c

So obviously that is normal.

and I clearly didn't read your message fully

"Do you get 1V1 LDO on both chips?
It will apear only on the powered port!"

 

[briancomputerdoctor]

Here are images of my USB-C redriver chip.

 

[briancomputerdoctor]

Here are images of both sides of the usb-c connectors.

 

[briancomputerdoctor]

Wider shot of the third image from the previous comment.

 

[briancomputerdoctor]

Diode mode to ground

C7023 is showing 10 to 20 kΩ

C7020 is showing 4 to 6 MΩ

 

[briancomputerdoctor]

Diode mode to ground

C7030

Pin 1 TBA_LX1 shows 0.660 MΩ

Pin 2 TBA_BOOT1_RC shows 32 MΩ

 

[2informaticos]

You can't get K/M ohm values in diode mode.
Multimeter will show "V" when switched to diode mode.
However, do not post the "V" for diode mode readings; avoid misunderstoods.

Read this thread for more information:

HOW TO collection

I hope this "How to" collection will help our members. I will possibly modify this post in time, if updates available. Trigger SMC_ONOFF_L (PMU_ONOFF_L): It reffers to simulate power button function, when the keyboard is not connected. We need to do this when we work with the board...

boards.rossmanngroup.com

One USB port is damaged.
You should compare (proper) diode mode readings between both ports (on the same pins).

 

[briancomputerdoctor]

SMC_USBC_INT_L gives 3.4v

SMC_RESET_L gives 3.4v