820-00850 5v 0,35A no corrosion no PP1V1_UPC_XA_LDO_BMC

[Bravo2001]

Hi all,

Got this board with a dead cd3215c00, there was a crack in it. So thought easy peasy. Changed the cd3215 U3200 with another one (ordered from ALI so not sure it was good) but still no 20v. Checked further and ppbus_g3h was 6v. After further inspection saw that another U3100 (cd3215c00) was getting very hot. So changed that to and now I have 12,3V PPBUS_G3H but still no 20v and no PP1v1 ldo BMC on u3200/u3100 and UB400 (while connect on the corresponding port) Only on UB300...

I used like 3 other CD3215C00 chips all no bmc. Then I found a donor board with working 20v cd3215c00 chips. Got them off en reballed and still no BMC. So I know for SURE it can't be bad batch of cd3215. I read on this forum something about changing the TBT rom, I have a lot of donors but never did a ROM backup. (don't know how) and don't want to before im sure that could be my issue.

Here are my readings:

PPBUS_g3h 12,3v
PP3v3_G3h 3,3v

U3200
PP1v1_UPC LDO BMC 0,484
PP1v8 LDOA 0.513
PP1v8 LDOD 0.470
PP3v3 LDO 0.459

U3100
PP1v1_UPC LDO BMC 0,491
PP1v8 LDOA 0.505
PP1v8 LDOD 0.471
PP3v3 LDO 0.467

UB300
PP1v1_UPC LDO BMC 0,507
PP1v8 LDOA 0.517
PP1v8 LDOD 0.481
PP3v3 LDO 0.496

UB400
PP1v1_UPC LDO BMC 0,498
PP1v8 LDOA 0.510
PP1v8 LDOD 0.476
PP3v3 LDO 0.490

Please let me know if you need more info...

There is no power cycling, all ports stay at 5v and 0,35a

 

[2informaticos]

When a CD3215 dies cracking, is very bad; that means its die was melt and 20V spikes into data lines.
T2 and CPU could be damaged.

Did you try DFU?
Be aware, if important data on SSD, go for Revive option, not Restore.
If machine is not recognized in AC2, check if all AWAKE and SLPS2R voltages are present.

 

[Bravo2001]

It was a small crack on top as shown on picture. Seen it before so I directly knew this was the bad cd3215. But after replacement and still no 20v I thought maybe a bad charger caused it and what clients do is try other ports. So thought maybe they destroyed more than one cd3215...

Just tried DFU mode, can't get it in to DFU mode. Want to force dfu mode... Tried with with jumping a wire between pin 1 en 2 of RE032 still nothing... Am I doing something wrong?

 

[2informaticos]

Onboard DFU force jumper must be closed when you plug the charger in.
Must open the jumper, once machine appears in AC2.

 

[Bravo2001]

Yeah did it like that, jumper between pin 1 en 2 but no duf mode...

 

[2informaticos]

Check if AWAKE and SLPS2R voltages are all there.

 

[Bravo2001]

Hi back to this board again! Now I'm a little bit further... All ports behave same! 5v, 400ma (a lot of current I know) Also all LDO's are present. So don't think problem is there.

PPBUS_G3H is 12,3v So communication issue between T2 and U7000.

All awake and SLPS2R Voltages:
PP1V2_AWAKE : 1,2v
PP1V8_AWAKE : 1,8v
PP3V3_AWAKE : 3.2v (was 0,2v and 2,8Ohm to ground after injecting 1 sec 3,3v in came back up)
PPVDDCPU_AWAKE: 0,75v

PP1V1_SLPS2R 1,1v
PP0v9_SLPS2R 0,9v
PP1V8_SLPS2R 1,8v
PP0v82_SLPS2R 0,82v

Never could get it in DFU mode. I'm hoping duf mode can restore it?! Help please

 

[2informaticos]

Still not getting 1V1 LDO?
In such case, there must be another problem on USB-C areas.

Test with original 87W charger and also battery connected.

 

[Bravo2001]

No all LDO's are now present... Still not getting 12,6v on PPBUS and no DFU

edit: Also no 20v on charger

 

[2informaticos]

Do you get any G3S, or SSD voltage?

 

[Bravo2001]

No G3S voltages:
PP5V_G3S 0v diode mode 0.404
PP1V8_G3S 0v diode mode 0.321
PP3V3_G3S 0v diode mode 0.289

No SSD voltages:
PP2V7_NAND_SSD0 0v diode mode 0.355
PP1V8_SSD0 0v diode mode 0.347
PP0V9_SSD0 0v diode mode 0.325

Was onder the assumption that these came later... Do I need them to get in DFU mode? Sounds logical as the firmware has to be written on the SSD.

Shouldn't we focus on why I don't have 12,6V onPPBUS? Is that not required before these come online?

Thxs in advance for the support

 

[2informaticos]

T2 firmware corruption will impede to get correct PPBUS_G3H voltage.
G3S and SSD voltages can come back in DFU mode.

Not sure what is wrong on 3V3_AWAKE, as you've got short there first.
The culprit was masked after voltage injection, but not found.
If machine can't enter DFU, T2 is the first suspect.

 

[Bravo2001]

Any more suggestions? I have a few donor boards... I can try to replace the T2. If it is possible at all? Otherwise I'm gonna trash the board... Customer didn't want it back anymore.

 

[2informaticos]

You can change T2 and its SoC ROM (U4770) at same time.

First compare diode mode readings on USB-C lines of DFU port with the other ports.

 

[Bravo2001]

I found a short on UPC_PMU_RESET 4,5ohm to ground. This is on all cd3215 chips and u7800.

Can I safely inject voltage? How much do you suggest?

 

[2informaticos]

Start with 1V, no more than 3.5V...

 

[Bravo2001]

After injection voltage, UB400 was getting hot. replaced it and also UB300 Because there was a solder bolt on it side. So now al the CD3215 are changed. and still no 20v. Checked all LDO's and looking good. Still 5v and 0,425A on amp meter on all ports.

PPBUS_G3H 12,3v
T2 is getting warm...

Can we get 20v without t2? So I want to know for sure t2 is dead before any attempt of changing it...

 

[2informaticos]

T2 must talk with CD3215 chips, in order to enable 20V on USB-C charger.
Did you try DFU mode after these changes?

 

[Bravo2001]

Yeah first thing after not seeing 20v... Didi it in case with the keyboard combo and als with the force DFU. NO sign of live!

I'm guessing there is no other option left to change the T2.

 

[2informaticos]

You can try flashing U2890 and UB090 first.
Nothing to lose flashing U4770 too.
Don't forget to backup all of them.