Saphhire R9 390X 8 GB, sources not present

[andreiut]

Hi everyone!

I’m new to this kind of job, i have an experience of around 15 years in electronic repairs but not so many in GPU’s repairs.

So, today, i’m facing a problem with my own R9 390 Saphhire edition.

So, all the ohms readings are fine (according to other YouTube videos), Vmem, Vcore, Display Rail, VRM ohms reading are good.

The problem is that all of my sources (except for 5V And 3.3 volts) are missing.

I know that the firing order for this card is:
5V -> 1.8V (which is not present. The controller will Take 5 And 3.3 volts, but nothing on the output, because His Enable pin will read 0.3volts, which is not enough for His 1.8V output signal) -> Display Rail (0.9v rails which is absent, due to no 1.8V signal) -> Vmem (absent, due to 0.9V rail) -> Vcore (also absent)

So, my question will be:
Who exactly will give command to this 1.8V source to power on?

From where does that 0.3 volts enable pin comes?
There should be over 0.4V in order to generate 1.8V signal to start the other sources of this card.


Hope i didn’t miss any Informations.
I didn’t included the ohms reading of vcore, vmem, display rail And other because i tought they might not be relevant now, since my problem is that i can’t get the general rails to start.

I’m stucked on the second rail, only the first one: 5V rail is present And corect.



Thanks!