8 pin connectors nolonger out put 12V afterusing the wrong GPU power cable

[akkk44]

I was using the Tyan B8252 server today and I randomly grab an 8pin-2x6+2pin GPU power cable and plugged it in without a second thought.
The 8 pin connector no longer outputs 12V ever since.
I think I have busted the 8pin connector on the motherboard.
A stupid and expensive mistake indeed.

 

[RolloZ170]

The 8 pin connector no longer outputs 12V ever since.
I think I have busted the 8pin connector on the motherboard.

motherboard type ? sure the 8pin is an output ?

 

[RageBone]

I was using the Tyan B8252 server today and I randomly grab an 8pin-2x6+2pin GPU power cable and plugged it in without a second thought.
The 8 pin connector no longer outputs 12V ever since.
I think I have busted the 8pin connector on the motherboard.
A stupid and expensive mistake indeed.

probably just blew a fuse, that should be replaceable.

 

[RolloZ170]

probably just blew a fuse, that should be replaceable.

aah i see, PSU plugged in the board. there are current measuring shunts. they blow up fast&easy.

 

[akkk44]

motherboard type ? sure the 8pin is an output ?

Yes, they were listed as PE_PW1- PE_PW5 outputs in the manual

 

[akkk44]

I connected the GPU and the motherboard with the wrong cable, the GPU and the cable seemed to be fine but the 8pin connector no longer output 12V

 

[akkk44]

Normally the connector will start outputting 12V after the system is powered on, but they now just stay at 0.x volts as the system is turned off.

 

[RageBone]

did you not say all of that already?

How about you post some pictures of the board around the port?
Maybe we can see the fuse / shunt?

 

[RageBone]

but i think that it is obvious that you done F'ed up and damaged the board in a way that makes that power-plug* not working.

So you either live with that and keep using the system without, or you do something about it.
It is likely fixable, will probably take some soldering though.

 

[RolloZ170]

Maybe we can see the fuse / shunt?

if they use small smd shunts like dell (PIB/PDB) you need another motherboard for parts, or RMA to manuf.

 

[RageBone]

https://www.servethehome.com/wp-content/uploads/2020/09/Tyan-Transport-HX-TS75-B8252-GPU-Power.jpg

If this is accurate, think there are nice and obvious white fuses located right around the plugs.
The angle of that picture is not optimal, so please post a nice top down picture of the area around the ports if you want confirmation.

 

[akkk44]

https://www.servethehome.com/wp-content/uploads/2020/09/Tyan-Transport-HX-TS75-B8252-GPU-Power.jpg

如果这是准确的，请认为插头周围有漂亮而明显的白色保险丝。
该图片的角度不是最佳的，因此如果您需要确认，请张贴港口周围区域的自上而下的精美图片。
[/引用]

Here is a top down view image,could you please point out the fuses you have mentioned so that I can take a closer look? Thanks a lot!

 

[akkk44]

Are the components that start with F on the board fuses? How can I tell if they are good or bad and what their specifications are?

 

[akkk44]

I have tried searching, does the letter S marked on the fuse mean it will blow at 4A current and that is the specification I am looking for?

 

[RageBone]

Yes, the letter F on Silkscreens usually denotes a Fuse.
I am not really versed in Fuses, but i know that they are categorized by how quickly they blow.
S probably meaning "slow" in this case.

You can check a Fuse with a multimeter by either probing for the Voltages on it:
When powered the system is powered on, a good non blow fuse should have the same Voltage on both sides.Measured on DC voltage setting with black on GND and red on the fuse.

Or when the system is completely powered off:
By measuring the resistance of the fuse with the probes on either side of the fuse.
Resistance should be close to or 0ohms, depending on the specifics of the multimeter.

http://imgur.com/a/HMz7wXd

Fuses marked and the arrow is pointing at the port they are for.
That is pretty clearly visible from the PCB.


I think it is safe to assume that the Port you have observed no power going to, having a blown fuse.

The actual current capability, i can't say.
Whats the Watt rating of the ports?
at 12V its gona be more then 10A probably.
Maybe 15A?
Not that that really matters as long as the fuse gets replaced with something that can handle enough and blows at "too much"

 

[RolloZ170]

'S' is 4 Amps on most SMD fuses.
we need the vendor of these specific fuses.

a EPS 8pin can deliver 336 Watts (28Amps, 12Vx28A=336W)

Not that that really matters as long as the fuse gets replaced with something that can handle enough and blows at "too much"

I agree

 

[akkk44]

I noticed the manual mentioned that the 8pin GPU connector supports up to 20A. So 20A is what I am looking for? I wonder what is the Voltage spec of the fuse means, it is ok to choose any fuse above 12V and blow at 20A?

 

[akkk44]

I have ordered the fuses (24V 20A), insulated the board and practiced the useage of a hot air rework station for couple times on a prictice board.
Now the only thing I can do is to wait for the fuses and hope for the best.

 

[RageBone]

if that practice board is epyc, i want it : )

Hotair can be used for the fuse replacement, i'd go for something else though.
It can be tricky with a soldering iron, but i think i would manage and rather use that.
Or just dremel them away, it is way easier to soller something back in place one joint at a time.
Or use a sharpened screwdriver to cut the solderjoint and lift the fuses, the PCB should be able to take that.

If you stick to hotair, use way more capton tape and also some aluminium foil to shield the plastic connectors and especially those caps better.
If they are like the ones SM uses, you will kill them rather quickly with a lot of nasty fumes that are less then healthy.
Removing them for the operation is cleanest and safest method i think.


And make sure which fuse you are actually working on, there are multiple in the pictures that are not necessarily the fuse you care about.
Wouldn't be the first time for me to start an operation and then notice that i was working on the wrong part, Woops.

 

[gsrcrxsi]

Did you verify if the PSU itself is still sending 12V to the motherboard? Maybe the issue is the PSU and not the motherboard. Would hate for you to go to the trouble of replacing SMDs if it’s just a PSU problem