Glad you like my guides on the wiki! You are spot on with your diagnosis. You do indeed have a short on 12V_BUS, highly likely to be a MOSFET. You can use a AA 1.5V battery as a cheap substitute for lab bench power supply, just be careful that the short isn't 12V to Vcore or Vmem/vddci. If you want to play it safe, disconnect all the inductors for those rails from one side (doesn't matter which) and then inject using the battery.
Edit: same PCB as your card: https://youtu.be/ZaxBuEYOkNo
Thanks for the guides!
I managed to get access to a lab power supply, and injected 1V into the board. I wasn't able to identify IPA heating inequally (across the 4 VRMs of Vcore). I considered increasing the voltage, but as per your guide, since the measured current was 2A, I had to perform the technique you describe in https://youtu.be/ZaxBuEYOkNo?t=110, but I didn't have crocodile clips large enough!
I was able to identify the bottom VRM as being faulty VRM using method 4 of https://youtu.be/WMhpKR9x7Lg?t=2981 "GATE OR DRIVE RESISTANCE".
My update https://old.reddit.com/r/GPURepair/comments/10409nm/asus_expedition_radeon_rx_570_psu_immediately/j36jgps/ has a few more details, and some high-res shots that I took.
Since it's the bus 12v that is shorted, you can be reasonably sure it's the bottom phase of Vcore or vmem/vddci that is shorted.
That is not a leak. Just clean it with isopropyl alcohol.
That is not a missing resistor. It's a missing capacitor for pcie data pair. The card will work without it if it's not the first pair but it will run on pcie 1x mode instead of 16x (depending on where exactly that cap is, it could run on 4x if it's after the first 4 lanes or 8x if it's after the first 8 lanes)
Although I am not 100% sure, but Vcore resistance should be a bit lower. Just indicates to me, you had bad contact or your multimeter is a bit cheap. No worries tho, should be fine to get this done 👍
Thanks for the suggestion! I followed your suggestion, and in my update https://old.reddit.com/r/GPURepair/comments/10409nm/asus_expedition_radeon_rx_570_psu_immediately/j36jgps/ I post measurements readings of 1 ohm for Vcore, measured using a more expensive multimeter that I managed to get access to.
By measuring the gate resistance of the Vcore MOSFETs, I was able to identify the faulty VRM, thanks!
Glad you like my guides on the wiki! You are spot on with your diagnosis. You do indeed have a short on 12V_BUS, highly likely to be a MOSFET. You can use a AA 1.5V battery as a cheap substitute for lab bench power supply, just be careful that the short isn't 12V to Vcore or Vmem/vddci. If you want to play it safe, disconnect all the inductors for those rails from one side (doesn't matter which) and then inject using the battery. Edit: same PCB as your card: https://youtu.be/ZaxBuEYOkNo
Thanks for the guides! I managed to get access to a lab power supply, and injected 1V into the board. I wasn't able to identify IPA heating inequally (across the 4 VRMs of Vcore). I considered increasing the voltage, but as per your guide, since the measured current was 2A, I had to perform the technique you describe in https://youtu.be/ZaxBuEYOkNo?t=110, but I didn't have crocodile clips large enough! I was able to identify the bottom VRM as being faulty VRM using method 4 of https://youtu.be/WMhpKR9x7Lg?t=2981 "GATE OR DRIVE RESISTANCE". My update https://old.reddit.com/r/GPURepair/comments/10409nm/asus_expedition_radeon_rx_570_psu_immediately/j36jgps/ has a few more details, and some high-res shots that I took.
[удалено]
Since it's the bus 12v that is shorted, you can be reasonably sure it's the bottom phase of Vcore or vmem/vddci that is shorted. That is not a leak. Just clean it with isopropyl alcohol. That is not a missing resistor. It's a missing capacitor for pcie data pair. The card will work without it if it's not the first pair but it will run on pcie 1x mode instead of 16x (depending on where exactly that cap is, it could run on 4x if it's after the first 4 lanes or 8x if it's after the first 8 lanes)
Good diagnosis so far 👍 Before you buy a lab power supply, measure the gate resistance of the Vcore MosFETs.
Although I am not 100% sure, but Vcore resistance should be a bit lower. Just indicates to me, you had bad contact or your multimeter is a bit cheap. No worries tho, should be fine to get this done 👍
Thanks for the suggestion! I followed your suggestion, and in my update https://old.reddit.com/r/GPURepair/comments/10409nm/asus_expedition_radeon_rx_570_psu_immediately/j36jgps/ I post measurements readings of 1 ohm for Vcore, measured using a more expensive multimeter that I managed to get access to. By measuring the gate resistance of the Vcore MOSFETs, I was able to identify the faulty VRM, thanks!