Replace Power Supply Question

[ComicWisdom]

Hello again HP Community.

After a recent power outage my desktop will not boot. No POST - nothing. I hear the system fans spin up, but nothing on the monitor. I restarted several times, unplugged the power, and changed the HDMI cable and nothing changed... still dead.

Other than a bad motherboard or CPU I'm thinking I may have a bad power supply. Do you have any other suggestions?

If I replace my power supply - is a standard ATX supply what I need?

DEVICE: HP ENVY Desktop - 750-530qd, Product ID: Y4S07AV

[old_geekster]

@ComicWisdom , welcome to the Community.

If you are not using a surge suppressor it could be any number of components being affected by a power surge.  Check the power supply unit (PSU) first to see if it is working properly.  This is my first suspect as you stated.  The PSU is a standard ATX.  Check the capacitors on the motherboard to assure that they are flat on top.  If they are bulging the motherboard could be fried.  Check the memory by removing all of the memory and replacing one stick at a time and boot the computer.  Place the single stick in the slot closest to the CPU.  It is a bit more difficult to test the processor without a replacement.

[ComicWisdom]

Thanks @Old_Geekster. I'm going to pop the cover off shortly and have a look. I'm familiar with bad caps, so I'm going to check for those while I'm inside. I want to take the least expensive route to repair. Living on social security doesn't leave much after a few bills. I'll post back what I find. 👍

[ComicWisdom]

The caps look fine. No bulging or scaring underneath. Here are just a couple.

Are there any reported bad motherboards? Here is the one I have. It's a replacement - not original.

[old_geekster]

You are very welcome, @ComicWisdom!  I understand the money crunch.  This economy will make a pay check get short at the end of the month.

The Caps do look fine.  I haven't heard of any bad motherboards lately.  However, I am always concerned about them when I hear about a power outage.  I definitely would check the PSU.

[ComicWisdom]

It's working!  I'm using my desktop to post this message.

Here is what I think happened:

(Back story)...  The USB ports on my setup are not easily accessible.  A few days ago I purchased a USB hub.  The one I got is a USB 3.0 and comes with a 5 volt DC power supply.  Another freakin' wall wart.  The power supply isn't really needed, but I figured - what the heck - go ahead and use it.

Fastforward to today.  I pulled the system power cord from the power supply and opened the case.  The system power supply features a green light to indicate it is receiving electricity.  Unplug the power and the light goes off.  Well, the light was lit even though the power cord was disconnected.  Strange!  One at a time I removed the other sources that were plugged in.  Audio out, the USB keyboard, the USB 3.0 connection, and poof!  The light went out.  At first, I didn't think much about it.  While my wife and I were out of the house today I was ruminating on what might cause the "no boot".  Could the back-feed of the 5V power cause the problem?  Does the system power supply misinterpret 5V?  It must!

Back at home tonight, I plugged in the system power supply, the monitor, and keyboard and the computer booted up just like normal.

I hope this might be a lead to other problems folks might have in the future.

[old_geekster]

Wow!  This is a new one on me!  In my 30+ years of using and building computers I have never heard of this happening.  Thank you for sharing it with us!

[ComicWisdom]

It may be coincidence. Or the HP gods took pity on me. I'm not sure. But that's the only change. I guess I could perform do-diligence and test this theory and reconnect the power to the USB hub to see what happens. Although, I wouldn't want to anger the HP gods.

If it's alright with the mods, I'll leave this thread as unsolved for now. If this issue returns I'll post an update.

[old_geekster]

Thank you for the additional information, @ComicWisdom!!