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So, I'm continuing to troubleshoot my Vega 64, no display, no fan issue. Figured maybe reposting in the AMD flavor area might be a good idea. Any help greatly appreciated!
to quote the other thread:
"When powered up the 12 phases are all getting 900mV, HBM is getting 1.2V, 5V rails are good on the front and back, PCIe rail has 800mV, Memory controller has 900mV. All the reading I took are in the attached image. The card gets hot, but fan does not spin, and no display out."
So, I was poking around in the PLL area (area under the GPU) and comparing to a known good card. I found that these two capacitors (double arrow in the image) are showing 7 ohms to ground on the bad card, and 2.7k ohm on a good card. So I think I may be on to something. I was able to find the datasheet for the APL5620, which is the 10 pin device (U375) in the photo that provides the ultra low output power (for the GPU core I think). I'm still working on mapping those pins, I need a smaller probe tip for my multimeter. I can confirm that two of the pins on the 6 pin IC are connected to the small tan 0402 capacitors (which appear to be in parallel to ground), which is where I'm getting my 7 ohm reading.
I'm far from an expert with this stuff, so hopefully someone can enlighten me. So my thoughts for the moment... and questions
1) Would the PLL area not working cause the effects that I'm seeing? I tried researching the PLL area of a video card but am still a little fuzzy on what it does.
2) Does anyone know what the 6 pin IC is? Markings say 4000000, OCP1445, 3416
3) I'm hoping the IC isn't faulty if I can't figure out what it is, but I can try replacing the pair of capacitors... but I don't really know what the values should be without being able to find a datasheet for the 6-pin, is there any goto value I could use? I'm not really wanting to desolder from a working board just to check them. I'll have to order a 0402 size capacitor sample pack to mess with it in any way, as I don't have any.
to quote the other thread:
"When powered up the 12 phases are all getting 900mV, HBM is getting 1.2V, 5V rails are good on the front and back, PCIe rail has 800mV, Memory controller has 900mV. All the reading I took are in the attached image. The card gets hot, but fan does not spin, and no display out."
So, I was poking around in the PLL area (area under the GPU) and comparing to a known good card. I found that these two capacitors (double arrow in the image) are showing 7 ohms to ground on the bad card, and 2.7k ohm on a good card. So I think I may be on to something. I was able to find the datasheet for the APL5620, which is the 10 pin device (U375) in the photo that provides the ultra low output power (for the GPU core I think). I'm still working on mapping those pins, I need a smaller probe tip for my multimeter. I can confirm that two of the pins on the 6 pin IC are connected to the small tan 0402 capacitors (which appear to be in parallel to ground), which is where I'm getting my 7 ohm reading.
I'm far from an expert with this stuff, so hopefully someone can enlighten me. So my thoughts for the moment... and questions
1) Would the PLL area not working cause the effects that I'm seeing? I tried researching the PLL area of a video card but am still a little fuzzy on what it does.
2) Does anyone know what the 6 pin IC is? Markings say 4000000, OCP1445, 3416
3) I'm hoping the IC isn't faulty if I can't figure out what it is, but I can try replacing the pair of capacitors... but I don't really know what the values should be without being able to find a datasheet for the 6-pin, is there any goto value I could use? I'm not really wanting to desolder from a working board just to check them. I'll have to order a 0402 size capacitor sample pack to mess with it in any way, as I don't have any.
