I have no lights on MB or back of power supply. I have replaced power supply and added a redundant power supply. I replaced PD board or backplane whatever you want to call it. Still same result. Replaced motherboard same issue. Have tried the plug power supply in before inserting into server no luck. I am totally lost at this point. What can I try next?
HP ML350 G6 will not power on
diagnosticelectrical-powerhptroubleshooting
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I have a multimeter, but I've never used one before. How can I check to confirm or rule out the on/off switch? Are there any other items I might want to check?
Turn your multimeter to the Ω/Ohm/Continuity tester. The Ω represents the amount of resistance in a circuit. A piece of wire (closed circuit) should have a resistance that is near 0 ohms. Air (open circuit) will have a very high resistance, most likely infinite from the perspective of your meter.
A power button on an ATX motherboard is a momentary switch. That means the circuit will only be closed when you press it.
Here is how I would test. Find two paper-clips and insert them into the motherboard connector for the power switch. Make sure the paper-clips to not touch each other. Touch one of the probes to one of paper-clips and the other probe to the other. While you have both probes contacting the paper-clips press the power button. If the button is good the reading on your multimeter should go from infinite ohms down to about zero.
BTW, if your case also has a reset button, you may be able to use that as a replacement for the power switch.. On an ATX case the reset button is just another momentary switch.
The typical scenario implemented when using UPS is:
- On power loss, the UPS notifies the software component on the system(s) connected to it.
- If the power is lost longer than n seconds, the UPS driver notifies the UPS and halts the system without powering it off (this is important).
- UPS waits m seconds for the systems to halt, and cuts the power off.
- When the power is restored and UPS battery is charged above minimum (so that it can support a power on and clean shut-down in case power is lost right after machines start booting), UPS restores the power to the systems.
- Systems notice (at BIOS/UEFI level), that they were powered on before they lost power, so they boot up.
In most server BIOSes you can set the system to restore power state from before power loss. This means, that if the server is powered down and power is lost, it will remain powered down after you plug it in. On the other hand, if it was powered on, when the power was lost, it will power up when AC is restored.
NUT mentioned by BillThor should allow you to realize this scenario.
Best Answer
Make sure that at least standby power LED gets on.
Disconnect everything from the motherboard and try again with a single PSU and CPU, no RAM, RAID controller etc.
Find the CMOS reset button and clear BIOS.
Look for leaking electrolytic capacitors
and physical damage to the motherboard.