Hi, have to repair a laptop HP DV6 Quanta R12 with problems in hdmi connector. VGA works ok. Lcd also works perfect.

Checking video signals in hdmi connector with oscilloscope shows nothing in C_TXC_HDMI+, C_TXC_HDMI-, C_TX0_HDMI+, etc. but it has pulses in HDMI_SCL_R and HDMI_SDA_R.

Problem is the same in linux or windows.

I suspect that U8 is not working properly.

Anyone knows something about this problem?

I am sorry, forgot to mention that L28, L30, L31 and L32 are missing, and they are very important to video signals reaching the output connector CN18, But seems that manufacturer omit them on purpose.
Seems that this signals are routed by another way, but cannot see it. this board is a discrete one, perhaps this component are for UMA only.

Hi, check these resistors

Thanks for this information, I did not notice this resistor in the schematic.

R391 is missing but R393 is mounted and I can read 4.7k from pins of R393.

R407 and R408 are both missing. (HDMI_CFG0)

R406 is also missing and R404 is mounted. (HDMI_CFG1)

Can you explain which resistor should be mounted?

Marking U8?

The HDMI TM /DVI TM LEVEL SHIFTER (U8) is coming, as soon as change it, I will let you know.
I think it is the damaged part in this board. (I hope)

See the RDT column for PS8101.

Confirmed, U8 is damaged.

After changed it, HDMI works¡¡¡¡