Okay. I was getting excited and tried to internally power and LCD replacement off the J15 connector -- using 4 12 volt lines and 4 GND lines to power a barrel connector and a 12 volt LCD -- yep. Shouldn't have done this. The LCD did power on; but now my computer will not boot. NO smoke; no pop, no obvious overheating.
What is working:
Looking at the schematic, R13 (1 kΩ) connects SYS_RST* to the CPU GLU NORM_RST* signal. My next thought was to lift one side of R13 to determine whether the PMGR side or the GLU side is asserting reset.
Thanks for any guidance.
What is working:
- F1 good
- +12V converter working
- Main +5V present
- +5V reaches RAM
- No hard short on +5V
- No hard short on +12V
Where I’m currently stuck
The machine has valid power rails, but:- SYS_RST* never releases
- RESET stays low
- HALT stays low
Looking at the schematic, R13 (1 kΩ) connects SYS_RST* to the CPU GLU NORM_RST* signal. My next thought was to lift one side of R13 to determine whether the PMGR side or the GLU side is asserting reset.
Questions
- Has anyone seen this failure after overloading the J15 +12V rail?
- Is lifting R13 the best next diagnostic step?
- Is there a known failure in the PMGR, hybrid, or CPU GLU that will permanently hold SYS_RST* low while +5V and +12V remain normal?
- Is there another signal I should measure before lifting R13?
Thanks for any guidance.
