KC Micro Tronix
Member
The machine came in for this problem and there are no signs of water damage anywhere. I looked under the chips as well! Went over the board half a dozen times looking for anything that could cause this. I think we are looking at a non water related issue.
I have a 820-00165 LB that never sends the 3.3v enable signal to turn on power to the LCD The screen never comes on and never has back light as a result.
All the power rails appear functional and voltages on the CPU are normal.
After looking at the board under thermal imaging I noticed that the RAM modules were never showing activity. What I normally observe is once CPU power is on and U3900 fires up the BIOS program is loaded into ram and starts running. You can see the memory light up slightly as it comes to life. on this board it does not.
I backed up and replaced the BIOS and this did not help.
Clock signals are present.
I can watch the CPU read the BIOS on the scope.
On the memory modules MEM_( A or B) _CLK signals are both not present.
Memory 1v2 and 1v8 s3 rails are present and working properly.
I have a 820-00165 LB that never sends the 3.3v enable signal to turn on power to the LCD The screen never comes on and never has back light as a result.
All the power rails appear functional and voltages on the CPU are normal.
After looking at the board under thermal imaging I noticed that the RAM modules were never showing activity. What I normally observe is once CPU power is on and U3900 fires up the BIOS program is loaded into ram and starts running. You can see the memory light up slightly as it comes to life. on this board it does not.
I backed up and replaced the BIOS and this did not help.
Clock signals are present.
I can watch the CPU read the BIOS on the scope.
On the memory modules MEM_( A or B) _CLK signals are both not present.
Memory 1v2 and 1v8 s3 rails are present and working properly.
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