HP Quadro K2100M MXM 3.0 type-a Laptop GPU short-circuit

[Teeri]

Hello
My trusty old HP Zbook 15 G1 died the other day. After disassembling it and fiddling around with, I found out that it's actually the nVidia Quadro K2100M MXM 3.0 type-a GPU card that is the culprit. Futher investigation lead to the realisation that the PWR_SCR lines of the card are shorted to ground.

Symptoms on the laptop.
When I connect the power supply, with no battery, the white led next to the connector flashes once. No other signs of life. After this the power supply does not work for couple of minutes, so I quess it goes in some sort of safe mode, because of the short-circuit/over current.

After removing the MXM card the system boots up normally.

I have measured the PWR_SCR pad's to ground on the card and they show 1.7ohm. I have not been able to find any schematics or boardview files for the MXM card.
Visual examination has not revealed anything obvious. I tried to measure the mosfets (CSD87350Q5D from TI, I think.) on the card, but to my understanding they are good. I have tried to inject voltage to the PWR_SCR and GND pad's and used isopropanol to find the short, but no luck. I only used 1V and 250mA.

What can I try next? More volts & amps? Is the 1V and 250mA enough? The thing is alredy broken anyway.

Any advices, tips or ideas would be much appriciated, as would be hints, where I could find schematics for the card.

I can take better pictures, if required.

[ktmmotocross]

Re: HP Quadro K2100M MXM 3.0 type-a Laptop GPU short-circuit

1V x 0,25A = 0,25W this power do not heat even microscopic capacitor.

remove coils and check on what side is short

[piernov]

Re: HP Quadro K2100M MXM 3.0 type-a Laptop GPU short-circuit

Shorted high-side

[khaahk]

Re: HP Quadro K2100M MXM 3.0 type-a Laptop GPU short-circuit

Remove the two mosfets which power gfx core and test offboard. One of the transistors should be for the vram power (most likely the one next to L2) - this should not be the one making trouble. You will need good hot air station to remove them. Increasing voltage is dangerous because you are sending the injected voltage directly to gfx core.

[ktmmotocross]

Re: HP Quadro K2100M MXM 3.0 type-a Laptop GPU short-circuit

Shorted high-side

1.7ohm is too low for highside. this gpu is based on 660gtx so gpu only have resitance more than 4ohms. 1.7ohm can have only when gpu is burned

[Teeri]

Re: HP Quadro K2100M MXM 3.0 type-a Laptop GPU short-circuit

Well I think I found it. I gave it some more juice and C112 was getting hot and when I removed it the short was gone. Now if I just knew what it's value is, so I can try if replacing it fixes the card.

[piernov]

Re: HP Quadro K2100M MXM 3.0 type-a Laptop GPU short-circuit

1.7ohm is too low for highside. this gpu is based on 660gtx so gpu only have resitance more than 4ohms. 1.7ohm can have only when gpu is burned

Always the first thing to check regardless.
Could already have damaged the GPU by injecting some random voltage.

[Teeri]

Re: HP Quadro K2100M MXM 3.0 type-a Laptop GPU short-circuit

Well. According to Mobile PCI Express Module Electromechanical Specification (page 30)
the specification for PWR_SCR lines is 7-20V and up to 10A. I am no expert here, but I think injecting 4V 2A to them, is somewhat safe, or atleast not insanely risky as the card was nonfunctional anyway.

I have ordered some 1206 10uF, 25V, 10% X5R MLCC capasitors, to replace the shorted one, the closest I could get to the ones recommended in the mosfets (CSD87350Q5) datasheet as input capasitors.

I measured the capasitor, after I removed it and I still got the same 1.7ohm on it. We will see, hopefully in the next week, if it will work. If it does not, atleast I am one experience richer. After all, this is just to edjucate myself in repairing electronics.

I appriciate all of your messages. I will keep you updated, just so we all can learn from this experiment.

[ktmmotocross]

Re: HP Quadro K2100M MXM 3.0 type-a Laptop GPU short-circuit

Well. According to Mobile PCI Express Module Electromechanical Specification (page 30)
the specification for PWR_SCR lines is 7-20V and up to 10A. I am no expert here, but I think injecting 4V 2A to them, is somewhat safe, or atleast not insanely risky as the card was nonfunctional anyway.

I have ordered some 1206 10uF, 25V, 10% X5R MLCC capasitors, to replace the shorted one, the closest I could get to the ones recommended in the mosfets (CSD87350Q5) datasheet as input capasitors.

I measured the capasitor, after I removed it and I still got the same 1.7ohm on it. We will see, hopefully in the next week, if it will work. If it does not, atleast I am one experience richer. After all, this is just to edjucate myself in repairing electronics.

I appriciate all of your messages. I will keep you updated, just so we all can learn from this experiment.

if u have shorted highside mosfet that 4V goes right to GPU. thats why u need to check it before injecting, or inject 1V

[Teeri]

Re: HP Quadro K2100M MXM 3.0 type-a Laptop GPU short-circuit

I am sorry for not updating this, but better late than never, right?
I got it fixed. Soldered the cap I ordered from ebay and the card is working like new and it has done so almost a year now. The card worked with out the cap too, but just to be safe I soldered the new one there anyway, so I am 100% sure the short was on the cap. Lucky me, right?

For anyone considering this fix I would suggest to do it the way many wiser than me said in the above posts. You might not be so luky and might fry your GPU like the experts say. In the end, the MXM card was my own and I was willing to take the risk, but if it had been some one elses that I was repairing, I would not suggest the way I didi it.

[athos231]

Re: HP Quadro K2100M MXM 3.0 type-a Laptop GPU short-circuit

Well I think I found it. I gave it some more juice and C112 was getting hot and when I removed it the short was gone. Now if I just knew what it's value is, so I can try if replacing it fixes the card.

Hi, I have the same problems with my MXM. Could you tell me where exactly did you put the voltage and how much did you actually put?

Regards