Dell E6540 No RAM detected.

[Andreasbest]

Re: Dell E6540 No RAM detected.

Yes that's what i'm telling.
The boardview shows the PR208 is in the 3rd SMD position from the bottom but as you can see is the actual photo of the MB it isn't.
Never soldered, same on donor board.

[SMDFlea]

Re: Dell E6540 No RAM detected.

It shouldn`t be populated. The resistor icon is underlined,that means its a solid pcb track ,you can see it on your picture,theres no break in the trace

[Andreasbest]

Re: Dell E6540 No RAM detected.

Yes indeed, 3rd SMD position from bottom has no break in trace. just noticed.
Good eye mate

[Spider1211]

Re: Dell E6540 No RAM detected.

Yes correct, I didnt pay attention to schematic until I saw the picture.

[Spider1211]

Re: Dell E6540 No RAM detected.

You are missing SUS_ON, check if +3.3V_SUS is present. I doubt it'll be. You can check on pin 8,9 of U104

[SMDFlea]

Re: Dell E6540 No RAM detected.

Go on the "options" tab then do the following:
- Select "etch" in 1st drop down menu, then select "Top" in 2nd drop down menu and click on the small square. This will display the tracks. Do same for "Bottom" if you need to see the bottom tracks as well.

- Next select "Ref Des" then choose:
"Assembly Top" to display components reference (R761, etc)
"Silkscreen Top" to display IC reference (u46, etc)

Dont forget to click the small square to activate it.

Play around with the other layers to see what suits you.

Thanks for the info, i always struggle using this software

[Spider1211]

Re: Dell E6540 No RAM detected.

To be honest, me too . I only just figured it out to help OP.

Maybe you could pin the comment or put it in a sticky post somewhere related to the topic if you think it may help others as well.

[Andreasbest]

Re: Dell E6540 No RAM detected.

8 & 9 have common trace and 0v

[Spider1211]

Re: Dell E6540 No RAM detected.

Could be a faulty SIO. Follow the power sequence on page 71 of schematic and see until what stage is working.

[Andreasbest]

Re: Dell E6540 No RAM detected.

I see it but i can't understand a thing, can you help me please?

[Spider1211]

Re: Dell E6540 No RAM detected.

You would usually start with number 1 then move up from there. 1 then 2, 3, 4, etc.

But in you case, since we already know its powering on, you can start at stage 2AC.

At stage 2AC you need to measure voltage +5V_ALW and +3.3V_ALW. If both are present, you move to step 3 which is measure +3.3V_ALW_PCH. If its present, you move to step 4. If not, report back until what stage was OK.

You can expect stage 8 not to work since we know SUS_ON is missing. This also means steps 8 onwards might not work.

[Andreasbest]

Re: Dell E6540 No RAM detected.

I found +3.3V_ALW_PCH in step 3, what is step 4?
It writes PCH_RSMRST# but what is it?

[Spider1211]

Re: Dell E6540 No RAM detected.

Its a signal. Just copy the name as is and do a search in the schematic. It'll tell you where you can measure it. Or you could also use the boardview to locate components on which you can measure the signal.

In this case, schematic returned 6 results. PCH_RSMRST# originates from SIO (pin B47) but since its a DQFN type IC, you cannot measure it directly on the chip itself. So just click next in the search results until you find a component that is accessible to you, which would be R892 or pin 1 of U9.

[Andreasbest]

Re: Dell E6540 No RAM detected.

U9 pin1 has 3v but not steady, probably because is a signal.

[Andreasbest]

Re: Dell E6540 No RAM detected.

R23 is the easiest place to measure SIO_SLP_S5# but i can't find it. How can i search for a component in Boardview? The Find tab is greyed out.

[Spider1211]

Re: Dell E6540 No RAM detected.

What do you mean by not steady? Actually when we refer to signal, we usually mean low voltage low current (uA to few mA). Something that does not need to power big loads.

PCH_RSMRST# means that a reset state will be enabled if this "signal" is LOW (denoted by the #). We do not want something to be constantly in a reset state, therefore we would expect this signal to be a non-zero value (usually 3.3V) when its not in reset.

Do you have a DSO which you can use to provide a picture of what that signal looks like?

[Spider1211]

Re: Dell E6540 No RAM detected.

The Find tab is greyed out.

I think it depends on the "type" of allegro you opened. When you install the program there are 2 versions created such as: Allegro Free Physical Viewer 16.6 and Allegro Free Physical Viewer 16.6 (no openGL).

Do not use the (no openGL), also try to run it as administrator.

[Andreasbest]

Re: Dell E6540 No RAM detected.

All good 3.3v on it, ground probe wasn't tight.

[Andreasbest]

Re: Dell E6540 No RAM detected.

I already tried that, the Find menu remains greyed out, can't type or check any of the boxes.

[Spider1211]

Re: Dell E6540 No RAM detected.

Try restarting the software? Maybe close, clean temp folder then try again.

It doesn't seem grey out in you picture post #41. Just hover your mouse over the 'Find' tab and see if that helps.