820-3476 no display on mini display port

[VinceLx2]

Hi,
This board had few small spots of water damage, I repaired them, and now I have chime, orange light on charger, but no display on mini display port. Internal display is ok, blinking folder.

R5350 and R5351 are ok, 2 kohm, voltage on all their pins is 3.4V

PP3V3RHV_S4_TBTBPWR_F = 3.3V
PP3V3_S4_TBTAPWR = 3.3V

PP15V_TBT =0V
TBT_A_HV_EN =0V
S4_PWR_EN =3.3V

R2887=10 kohm

Any idea how to continue?

 

[2informaticos]

HDMI also not working?
Thunderbolt problems usually not worth to spend time only for external video.

Check TBT_A/B_HPD on U3220/320, depending which port used.

 

[VinceLx2]

HDMI is not able to display the blinking folder, correct? I should test from OS X?

 

[VinceLx2]

So, for what I have checked also with another board, there is no blinking folder possible on HDMI.
For this board HDMI is working, within OS X

With display port connected on A:
TBT_A_HPD = 3.3V
DP_TBTPA_HPD =3.3V

 

[VinceLx2]

Any idea to try to solve this issue?

 

[2informaticos]

15V_TBT is there?
Do you get voltage at C3211/86?
Check the other port too.

 

[VinceLx2]

PP15V_TBT = 0V, with or without cable connected
In diode mode, I have 0.56V on C3315
PPVIN_SW_TBTBST = 0V
TBT_A_HV_EN = 0V, with or without cable connected
also,
TBT_B_HV_EN = 0V, with or without cable connected

Port A:
On C3286: PP3V3_S4_TBTAPWR =3.3V
On C3211: PP3V3RHV_S4_TBTAPWR =3.3V
Port B:
On C3386: PP3V3_S4_TBTBPWR =3.3V
On C3311: PP3V3RHV_S4_TBTBPWR=3.3V
I have these values with or without cable connected

 

[2informaticos]

Check if U2800 gets all required voltages (page 24).

 

[VinceLx2]

Here are the voltages on U2800:
PP1V05_TBTRDV = 1.01V
PP1V05_TBT = 1.01V
P1V05TBT_SW = 0.95V
PP1V05_TBTCIO = 1.00V
PP3V3_S4_TBT = 3.3V
PP3V3_S4_TBT_F = 3.3V
PP3V3_TBTLC = 3.3V
PP3V3_TBTRDV = 3.3V

TBT_EN_CIO_PWR_L = 0V
TBT_PWR_REQ_L = 0V

Seems ok. I have these values with or without cable connected

 

[2informaticos]

Check TBT_POC_RESET_L and TBT_PWR_ON_POC_RST_L.

You can try changing/reflashing U2890.
If still the same, change U2800.

 

[VinceLx2]

TBT_POC_RESET_L = 3.3V
TBT_PWR_ON_POC_RST_L = 3.3V

Can I try to replace with U2890 from a spare 820-3787 board, also with 2 display ports?
Do you have a dump for this chip?
I can flash with the same tool I use for SPI ROM/BIOS, correct?

 

[2informaticos]

U2890 is a SPI chip; any BIOS programmer should do the job.

 

[VinceLx2]

Ok.
Can I try to replace U2890 with the same chip from a spare 820-3787 board, also with 2 display ports?
Do you have a dump for this chip?

 

[2informaticos]

I don't have TBT ROM for these old machines.

Don't forget to make backup of them first.

 

[VinceLx2]

Ok, last question: can I try to replace U2890 with the same chip from a spare 820-3787 board, also with 2 display ports?

 

[2informaticos]

You can try, but...
If doesn't work, you can't be sure if is incompatible, or board has other problem,