Mellanox/EMC SX6012 - Revival Attempt

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RageBone

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Jul 11, 2017
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exactly what necr said, i swear i have seen an error message exactly like that in one of the first and shorter console outputs that you have shown.

The reason for that is most likely an issue with one or more voltage rails.

To reiterate, Stuff does not just take 12v from the PSU.
SOCs, CPUs, GPUs take a lot of different voltages.

Most common are: 5V and 3.3V with Stand-By variants that are always on, so that the thing can ron on something low poer and then detect the power-button and turn on.
And 1.5V or 1.2V for DDR variants,
1V Vcore for the actual Switch "core"
And possibly other Perifery stuff, 1.8V PLL, what ever.
Many different voltages.

AS far as i could read the labels in your pictures / videos beside the green LEDs, for example with the blinking one that is not readable to me,
it looks like that is indicating the main 12V rail being wonky and since everything else gets created from there, nothing worked.

In later videos and pictures, still not readable to me, shoddy stuff honestly, it looks like you are still missing some of those needed voltages.
I can't tell you exactly which and how many because i don't have such a switch anymore and i can't honestly read and see stuff in anything you showed us so far.

My best bet currently is that you had a dead cap short the main 12v rail which caused that wonkyness, prolonged torture of that cap then blew that one up that its not shorting anymore and not you have a second issue of possibly VCORE not turning on and hence keeping the switch chip off.

excuse the rambly style, but i'm frustrated with your lack of cooperation so far.
 
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gb00s

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Jul 25, 2018
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... excuse the rambly style, but i'm frustrated with your lack of cooperation so far.
No worries if I need tissues, I will let you know. My problem is without a diagram I don't know where to measure the necessary parameters. The descriptions on the board are not helpful for me either. I understand and I will make some pictures as you requested.
 

RageBone

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Jul 11, 2017
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My problem is without a diagram I don't know where to measure the necessary parameters. The descriptions on the board are not helpful for me either. I understand and I will make some pictures as you requested.
Yes exactly.
There are things that "experienced" "technikitans" can swing along though, so those many many detailed and high res pictures would help with that a lot!
Looking forward to those
 
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RageBone

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well, since you did not provide pictures yet, i got bored and looked at your videos again.

If i wanted, i could read the stuff beside the LEDs.

And wonder oh wonder, those LEDs are labled "Voltage PG" and "PG" very likely means "POWER GOOD".
Usually a logic signal to indicate that the voltage regulation is enabled and working as it shood.
= > Good Power ...
Lit up are:
3.3V AUX PG
VCORE PG
1.8?V PG
Not Lit up:
5V PG
3.3V_SX PG

So you have 100% an issue with the powerdelivery on the switch PCB.
Those two aren't necessarily dead, just, those rails missing is not good and for sure causes your switch to not work.
Just why they aren't working is now the question and again, they don't need to be dead, it could be something "upstream".

Ubiquity switches for instance run on 24V and more, and have a Buck-Converter to get that down to 12V for some rails like 1.5V MEM and 1V Core.
So if you don't have those two, could be because the 12V Buck died, and you would be wrong to blame MEM and Vcore.

Understood?

Pictures of the board please.
Befoer you scream that you have no idea where what is, i have no idea either, unless i can see stuff with my eyes and narrow it down a bit.
We would also initially be looking for irregularities like schmoo and burned or ripped stuff.
So, even if you have no idea, PLEASE, PLEASE make a few hole board and deatil pictures, there is nothin on the web i could find and do that for you.


Or just put it in a ****ing package and send it to me. Could use a SX6012 myself.
 

gb00s

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Jul 25, 2018
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Will prepare pictures. Just have to get it to my work for good light. Thanks.

shipping? Please tell me you are not from US?!
 

necr

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Dec 27, 2017
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Lattice CPLD seems cooked, but I’d expect a problem somewhere close to power (VRM), could be something on the back side of the board - I’m not sure there are corresponding photos for that in GDrive yet. This huge CPLD should be easy to replace (re-ball) provided you find its P/N. But I leave this to Herr Technikittan (m/w/d) to check.
 
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RageBone

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Jul 11, 2017
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L50 on the 5V rail has a dent in it, maybe its dead and it looks like it could be an input filter coil, potentially cutting off the rail from the supply.
The 3.3V_SX rail not working could be due to power sequencing, but the TI Nexfet used on it could be faulty, those are good parts but everything can fail and i have many boards with those dead and shorted high, low, and both sides of the buck converter.

So please check L50 for resistance and continuity and potential short to Ground or short to Rail, and check the last two on the 3.3V_SX rail aswell.

Resistnace values of the two rails in question to Ground would be nice to know too.

I have marked those on pictures already, but i can't upload them from mobile and will have to redo those in the coming days.

Any questions?
 

RageBone

Active Member
Jul 11, 2017
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@necr i have again "overlooked" the dead cpld as "just shmoo" for instance from a thermal pad.

If the 3.3V_sx rail is used for that, a Highside short to output might be likely, and hence, killing it with 12V instead of the expected 3.3V.

Main issues with cplds and fpgas is that the FW ist mosten often stored on chip with no way to extract it, whoch makes replacing them useless since you also need the FW for it to do its job.

So, hoping the cpld is still good and its just shmoo.
 

gb00s

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Jul 25, 2018
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Thx for the comments.

I don’t know what you are talking about and I’m unable to identify the parts. I mean you are frustrated on me not providing photos ‘in time’, but for me I’m frustrated at the same level pointing me on something I already admitted to not have any clue about.This ’hey look here and there‘ doesn’t work for me without photos either. I mean if I admitted already I cant drive a car and you still want me to drive 600km, then sorry .....

I don’t want to spend more time on this. Already frustrated me a lot and just spending 200EUR would have brought me a functional switch, working setup and saved time.