Almost no power - fans start, then die

[mt14]

My HP Pavilion Slimline S5680t Desktop PC won't power on.  It is about 13 years old, and I usually leave it on all day and all night. The HD died 7 years ago.  I replaced it with a Samsung SSD.  I upgraded to Win 10 from Win 7 about 6 months ago.  All has been working flawlessly and tirelessly since the HDD was replaced.  

The other morning, I found it off.  Pushing the power button did nothing.  I found the green led on the back goes off when the power button is pushed.  But, when I unplug it and plug it back in, the green led re-lights.  The green led will also re-light if I hold the power button down for 5 seconds. 

When I opened the case, I found that all 3 fans start up when the power button is pushed.  They make less that 1 revolution, then stop, and the green led goes off.

I confirmed the power cord and outlet work. I disconnected all external peripherals (usb drives, camera, etc.)  I have cleaned dust off the fans, the board, etc.  There was quite a bit of dust on the CPUs heat sink.  Also, I tried disconnecting the SSD power and data, the DVD player power and data, and the power to the fans.  And, I re-seated the memory cards.

Any suggestions would be appreciated.

[Bill_To · Accepted solution]

Hi @mt14 

You have done very good troubleshooting steps.

I am guessing you have replaced the CR2032 MB many times over the last thirteen years.

I would say the power supply is failing or you have a MB problem or a CPU problem. You would have to try a known good PSU and try a different, compatible CPU to verify the MB has failed.

You could also disconnect FP (USB and the card reader). Try each stick of memory, one at a time, in each memory slot. Or try a different, compatible stick of memory in each memory slot.

Regards

[mt14]

Hi Bill-to,

Thanks for your response. It was very  helpful.

I know it's been awhile, but I finally got to checking the things you suggested. The last thing I checked was the PSU . I found that the PSU is defective. I used the paper clip test to see if the fan would come on, and I used a multimeter to check for voltage from each pin. It failed on both tests.

I started shopping for a PSU and found it very frustrating. I was wondering if you had any suggestions for finding a proper fit. I've tried searching based on the model number from the manufacturer and using the HP model number. Even with those numbers I get a variety of results in terms of power and size. Things are pretty tight In the HP Slimline that I have. HP does not carry it any longer. Thoughts?

Thanks again for your help.

[Bill_To]

Hi @mt14 

My pleasure.

Not much info available on parts used by HP in this PC. The power supply part number is available at HP Part Surfer.

Power supply purchase options exist using the HP power supply part number (504966-001) at eBay?

It is also possible you have a short somewhere which causes the power supply to shut down. Or more than one component has failed.

Regards