HP Envy 700-215XT fails to power up

[GollyGee]

PC fails to power up.  Thought it might be the power supply and purchased an ATX450 supply.  No change.  Tested the power connection button to the mother board F-panel connector pins 3&4 black wires with OHM meter and button works.   Believe the motherboard is not signaling the power supply to power on.   Tested the original power supply main connector by shorting pin15 common and pin 16 PS-on# and the fan runs on  power supply.      Measured voltage only 3v.    Did same on new power supply and it has 5v and 12v.   But needs the connection pin 16 to common to keep the power supply going.    Haven’t tried forcing the PS -on connection to common while connected to motherboard yet.     Bottom line is the question :  what is between the power button front panel and the power supply turn on control?     Has anybody experienced this?

[Grzwacz]

Greetings,

Welcome to the forum.

I am not a HP employee.

Nice troubleshooting.

It appears you may have a motherboard problem if the power switch works and you have tried a compatible power supply replacement. Voltages seem check out if I am following you correctly.

It does sound like the motherboard is the point of failure.

A short with any component or associated peripheral device connected to the motherboard may cause this.

Have you reduced component connections to the minimum required to get a POST?

Regards

[GollyGee]

Connected power supply with the 24pin connector pins 15&16 shorted with a paper clip and when the PS is powered, the fans run but no sound, and the voltage drops to 3 volts and 9 volts measured at c

d rom power connector.  No Hd or peripheral devices connected just the MB connections.   Probably is the MB. But n3ver had to replace one.     Is it worth trying?     Almost 4 yrs old   Concerned about programs on it

[Grzwacz]

Hi GollyGee,

You may have a hard time finding a HP replacement MB matching the factory installed MB. HP does not usually provide replacement parts for four year old PCs.

Try HP Part Surfer (Link). Maybe eBay?

Have you disconnected: the CD drive and front/top USB including the card reader?

You can get data from the existing HDD. You can try installing the HDD in a different PC as bootable. Win 10 should boot but you may have an activation problem. Data will be accessible.

Regards