Hello!
I got an 15" 2011 Hi Res, 820-2915 which chimes and boots into OSX but there is no video, just a black screen. Also on external I get no video.
What I did:
-PRAM & SMC reset (successful)
-tried another harddisc
-checked LVDS connector, supplies are there but LCD_PWR_EN does not enable U9000
-all power rails are there except:
PPVCCSA_S0_REG
only 0,9V
Checked U7100 (ISL95870A) and all components around, all ok. Regarding schematic, it should be 0,9V?! When VID0 and VID1 Voltage is 0, Output = 0.9V?!
PPVCORE_S0_AXG
0,9V but then falling down to 0,45V
PPVCORE_S0_CPU
1,15V but then falling down to 0,75V
I have checked current sensing circuit after the big coils on PHASE1,2,3,AVG and connection to U7400 (MAX17511). All ok.
That complete "PHASE" circuitry is a bit complicated to understand for me.....
Any ideas or hints how I should proceed or focus on??
THANKS
I got an 15" 2011 Hi Res, 820-2915 which chimes and boots into OSX but there is no video, just a black screen. Also on external I get no video.
What I did:
-PRAM & SMC reset (successful)
-tried another harddisc
-checked LVDS connector, supplies are there but LCD_PWR_EN does not enable U9000
-all power rails are there except:
PPVCCSA_S0_REG
only 0,9V
Checked U7100 (ISL95870A) and all components around, all ok. Regarding schematic, it should be 0,9V?! When VID0 and VID1 Voltage is 0, Output = 0.9V?!
PPVCORE_S0_AXG
0,9V but then falling down to 0,45V
PPVCORE_S0_CPU
1,15V but then falling down to 0,75V
I have checked current sensing circuit after the big coils on PHASE1,2,3,AVG and connection to U7400 (MAX17511). All ok.
That complete "PHASE" circuitry is a bit complicated to understand for me.....
Any ideas or hints how I should proceed or focus on??
THANKS
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