Hi
I have an 820-3332 that chimes, has fan spin and has disk activity (see indicator light on external drive flashing) but nothing appears on either internal or external display.
U8900 already re-soldered twice with no improvement.
For the reasons below, I'm pretty sure the GPU and/or Graphics MUX is fried but since the board has signs of life, I would appreciate any guidance that can be offered before I throw the board into the parts bin.
First the bad news: There was one spot of corrosion that had connected 12V8 at C8925-1 (PPVIN_S5_HS_GPU_ISNS == PPVIN_S0_GFXIMVP) to an UNUSED 3V3 level GPU output signal (GPU_ROM_SCLK) via this path:
U8000-H4 to R8724-2 (no stuff) to R8715-1 (no stuff) to R8714-2.
Now, the really bad news. The short also connected 12V8 to 3V3 (PP3V3_GPU_VDD33 == PP3V3_S0GPU) via this branch from the above circuit:
R8714-2 thru 24.9K to R8714-1 to C8721-1 (no stuff) to U8701-7, 8 (no stuff)
All the above traces were burnt out along with R8714 except for U8701-7 to U8701-8 and the 3V3 connection to R8714-1 pad.
All 3V3 users on both sides of the board are confirmed to still get 3V3 except I can't verify that U8000 (GPU) or U9100 (GPU MUX) are still getting 3V3 as the connections are hidden under those parts. Unfortunately, I do not have the equipment/skills to remove or replace those kind of parts.
For what it's worth, 3V3 is present at R8714-1 but not at C8721-1 or U8701-7 and 8.
Am I correct in assuming the GPU and/or Graphics MUX are fried and possibly other 3V3 users and this board should just be used for parts?
Again, would greatly appreciate any advice.
I have an 820-3332 that chimes, has fan spin and has disk activity (see indicator light on external drive flashing) but nothing appears on either internal or external display.
U8900 already re-soldered twice with no improvement.
For the reasons below, I'm pretty sure the GPU and/or Graphics MUX is fried but since the board has signs of life, I would appreciate any guidance that can be offered before I throw the board into the parts bin.
First the bad news: There was one spot of corrosion that had connected 12V8 at C8925-1 (PPVIN_S5_HS_GPU_ISNS == PPVIN_S0_GFXIMVP) to an UNUSED 3V3 level GPU output signal (GPU_ROM_SCLK) via this path:
U8000-H4 to R8724-2 (no stuff) to R8715-1 (no stuff) to R8714-2.
Now, the really bad news. The short also connected 12V8 to 3V3 (PP3V3_GPU_VDD33 == PP3V3_S0GPU) via this branch from the above circuit:
R8714-2 thru 24.9K to R8714-1 to C8721-1 (no stuff) to U8701-7, 8 (no stuff)
All the above traces were burnt out along with R8714 except for U8701-7 to U8701-8 and the 3V3 connection to R8714-1 pad.
All 3V3 users on both sides of the board are confirmed to still get 3V3 except I can't verify that U8000 (GPU) or U9100 (GPU MUX) are still getting 3V3 as the connections are hidden under those parts. Unfortunately, I do not have the equipment/skills to remove or replace those kind of parts.
For what it's worth, 3V3 is present at R8714-1 but not at C8721-1 or U8701-7 and 8.
Am I correct in assuming the GPU and/or Graphics MUX are fried and possibly other 3V3 users and this board should just be used for parts?
Again, would greatly appreciate any advice.
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