I'm trying to fix a Compaq CQ58 with power issues. Initially I noticed that it would run on mains power but not on battery, but I have since discovered that it is actually extremely sensitive to the DC power input voltage.
For instance, if I set the charger input to the full 19.5V then everything is normal and it runs absolutely perfectly. However, if I reduce it even to 19.0V it will boot to BIOS level but then just switch off as soon as I put any load on the system (e.g. by running a memory diagnostic). Presumably this explains why it won't run at all on the 11.1V battery supply.
Interestingly, it will pass the memory diagnostic at 19.0V with one DIMM installed instead of two - I assume that this is because either the memory or CPU power load (by switching to single channel) is reduced. However, at 18.5V - when it should still be running fine - it's back to crashing with even a single DIMM. Presumably this narrows down the problem area, though.
There seem to be two CPU power phases, but as thermal imaging shows them to be running equally hot then presumably they're both working.
Has anyone seen anything like this before, or can offer any ideas as to how to diagnose it further?
For instance, if I set the charger input to the full 19.5V then everything is normal and it runs absolutely perfectly. However, if I reduce it even to 19.0V it will boot to BIOS level but then just switch off as soon as I put any load on the system (e.g. by running a memory diagnostic). Presumably this explains why it won't run at all on the 11.1V battery supply.
Interestingly, it will pass the memory diagnostic at 19.0V with one DIMM installed instead of two - I assume that this is because either the memory or CPU power load (by switching to single channel) is reduced. However, at 18.5V - when it should still be running fine - it's back to crashing with even a single DIMM. Presumably this narrows down the problem area, though.
There seem to be two CPU power phases, but as thermal imaging shows them to be running equally hot then presumably they're both working.
Has anyone seen anything like this before, or can offer any ideas as to how to diagnose it further?
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