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820-00850 PP1V1_LDO missing in two CD chips

Rlab

Rlab

Member
Hi guys,
I'm working on a MB that came with a partial short an corrosion on CB300 and CB308 and had also a burned L8504.

Once CB300 & 308 were replace, PP3V3_G3H_RTC & PP3V3_UPC_TA_LDO came back but PP1V1_LDO is missing in UB300 & UB400 (PP1V8_LDO X2 are present)

Both CD chips (UB300/400) have been replace 3 times each from 2 different suppliers and im still missing PP1V1_LDO in both chips.
diode mode readings look good compered with U3100 & U3200 which have all LDOs present.

PPBUS_G3H 12.34 V
PP20V has 5V in all 4 ports

is there anything else besides the CD chips that can affect PP1V1_LDO lines?
 
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P

piernov

Moderator
Staff member

CD3215 Bootup Sequence - LogiWiki

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The TBT ROM is required to get to 20V. It is powered by the CD3215 on the opposite side. It will not boot unless it can communicate. It seems with liquid in that area, the trace between the LDO of the CD3215 and TBT ROM gets damaged at the test point. Without communication with the TBT ROM, the 1.1V BMC LDO (PIN 35) won't come up while other LDOs will be present. The 1.1V BMC LDO is used to drive the logic negotiating USB-PD (USB 2.0 communications to charger). When that happens, when USB-C is connected to this CD3215, it will not negotiate 20V and get stuck on 5V, not cycling.
Click to expand...
 
Rlab

Rlab

Member
Hi Piernov !

Thank you very much for this info.
I have replaced UB090 and i got back PP1V1_LDO in the master UB300 however PP1V1_LDO is still missing in UB400. So.. I have replaced UB400 again but still the same, no 1V1_LDO.. (no shorts around )

what do you think?
 
2informaticos

2informaticos

Administrator
Staff member
1V1 LDO only appears on the powered port.

Check UB400 surrounding resistors and traces.
UB300 boots from UB090, but UB400 boots from UB300, through UART lines.
 
Rlab

Rlab

Member
Hola 2informaticos !

Confirmed, I have checked 1V1_LDO only in the powered port.

Resistors and traces are ok
UPC_TA_UART_TX & UPC_TA_UART_RX have 3.35 V (both ports UB300/400)

I found a little diference in diode mode readings in PP5V_S4_T_USBC 0.148 compared to PP5V_S4_X_USBC 0.203

what do you think?
 
Rlab

Rlab

Member
RB305 0.94 M
RB308 0.94 M
RB309 0.95 M

RB405 0.97 M
RB408 0.96 M
RB409 0.94 M

Should I try another CD chip?...
 
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2informaticos

2informaticos

Administrator
Staff member
"PPBUS_G3H 12.34 V"
Was this reading with charger alone (battery not connected)?
If yes, do you get this voltage on all 4 USB-C ports?
 
Rlab

Rlab

Member
yes, reading was using only the charger.

Right now, after the changes and using only the charger as well, I have in PPBUS_G3H 12.29 steady in both ports ( UB300/400 ) but in the other two, where 1V1_LDO shows up (U3100/200) is not steady. It goes to 12.30 and then goes to 6.34 , 10.40 and then goes back to 12.30 and so on..
 
2informaticos

2informaticos

Administrator
Staff member
Seems that board tries to turn on and cycles on U3100/200 side.
But still has problems on UB300/400.

Check with charger and battery connected at same time.
 
Rlab

Rlab

Member
With the battery and charger connected, the cycles continue in the U3100/200 side it goes 20, 18, 0, 5, 8, 20 V and so on...
in the other side (UB300/400) goes :
UB300 5V
UB400 0V (not shorted) I do have 3.3_LDO and X2 1.8_LDO but still missing 1.1_LDO

Could it be that I had a very bad luck with the CD chips im replacing in UB400? or something else ?
what do you think?
 
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Rlab

Rlab

Member
I swapped UB400 with UB300.

Still same behavior...
at least I know my CD chips are fine :) hahahaha

any ideas?
 
Rlab

Rlab

Member
There are no corroded resistors or traces...

Could this be related to PP5V_G3S? L8504 was totally burned it even burned the pad...
I have 0.393 diode mode in that line...
 
2informaticos

2informaticos

Administrator
Staff member
5V_G3S is a common thing for entire board.
How can affect one USB-C port only?

Just in case, keep J8500 disconnected, until get correct voltages on the MLB.

You've mentioned about corroded caps found on USB-C area.
You had UB090 affected; UB000 may be affected too.
 
Rlab

Rlab

Member
Yea, just what I thought.. just wanted to make sure I wasn't missing something with that 5V_G3S line.


Unfortunately the client couldn't wait more.. so this one went out as No Fix..

Thank you very much anyways !
 
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