Solved: Dc7800 SFF won't start - HP Support Community

Pengzi · ‎03-04-2017

Hi guys,

My dc7800 small form factor suddenly won't start; there is no fans or any sound, when the on/off button is pushed.

There is a green light inside the desktop at the end of the ram slots. and when I push the on/off button there is a green light near the button lights up too.

I checked the PSU on its own and it starts up, when I connect a paper-clip between the green and a black led.

What shall I check next?

Best regards,

Pengzi

Pengzi · ‎03-22-2017

I got the PC to work at last! The motherboard needed a "reflow" and after that it worked like a champ. Has spent 0 dollars and used about 1hour for the whole thing :).

For others who also have problems with a PC, which won't start, no boot, here is a brilliant check-list, that you could follow and attempt resolving the problems: read this.

View solution in original post

erico · ‎03-05-2017

Have you followed the troubleshooting guide frm the support portal? Use the followin link.

http://h20565.www2.hp.com/portal/site/hpsc/template.PAGE/action.process/public/psi/manualsDisplay/?s...

I am a volunteer forum member, not an HP employee. If my suggestion solved your issue, don't forget to mark that post as the accepted solution. If you want to say thanks, click on the Yes button next to the "was this reply helpful?"

Pengzi · ‎03-13-2017

Hello Erico,

Sorry that I say this, but do you always just throw an standard answer trying to get "help-some-one points"? If you have read my post, you'll see that I couldn't even get my computer started, so how do I perform diagnostic etc.?

For your info, I've searched HP's forum and have followed the instructions to circle around the real problem, but could not find it. If you are familiar with start-up problems, I'd like to hear your view and experience of it, otherwise let someone else answer my questions, please!

regards, Pengzi

erico · ‎03-13-2017

That is not some standard answer. I gave you a link which provided a valid list of things to check. I am initimately familiar with start-up problems with desktop and notebook PCs.

If it won't start and there are no blinking leds nor blinking power supply, you will have to go down the long list that is appropriate to your installed OS in your PC.

If you are not willing to read through the list, then I suggest you take it to a shop and pay to have someone troubleshoot it for you.

Since it is a model that has not been on the market since 2010, you will have to consider whether or not it is worth spending the money to repair it.

Regards,

erico

I am a volunteer forum member, not an HP employee. If my suggestion solved your issue, don't forget to mark that post as the accepted solution. If you want to say thanks, click on the Yes button next to the "was this reply helpful?"

Pengzi · ‎03-15-2017

Thank you for your answer, erico!

I'm aware that this Pc is old, and maybe not worth it to pay an authorized dealer to look at/repair it; but it worked fine for my needs and that's why I hoped to get some advices here to get it to work again without having to rob a bank :)!

The manual you send me, I can only see one page (page 14) regarding problems with power. I've followed it and the only options left for me were: 1. Replace power supply and 2. replace mainboard.

Since I tried and estimated that the psu is in working order, I suppose I should get me a second hand mainboard to try it. From the HP-forum and other sites, it states that it is very unusual, that a mainboard should malfunction, but I guess I could be "unlucky".

Do you know if there is an step-by-step check-list to check the mainboard?

Regards, Pengzi

erico · ‎03-15-2017

You don't need an authorized dealer to look at it. Any certified PC tech at a shop can figure out what is wrong with it pretty quickly.

Unfortunately one cannot "estimate" that the PSU is operating as it should.

In order to do that you would have to put a resistive load on the PSU with and amp meter connected in series to see just how much power it will deliver.

Often a PSU will appear to be working but when it has to power a load it will fail.

The green led is not such a great indicator of PSU health.

That kind of knowledge is why people get paid to go through their checklists to see what is wrong with a PC. We are here to help with basic troubleshooting, but sometimes, as in your case, it really has to be hands on. That is how it is with electronics troubleshooting. It helps to already have some familiarity with specific sets of symptoms that point to probable causes.

If you go the motherboard swap route, make sure that you use tape to label where the connectors go onto the motherboard headers. There are labels already on the motherboard.

I am a volunteer forum member, not an HP employee. If my suggestion solved your issue, don't forget to mark that post as the accepted solution. If you want to say thanks, click on the Yes button next to the "was this reply helpful?"

Pengzi · ‎03-22-2017

I got the PC to work at last! The motherboard needed a "reflow" and after that it worked like a champ. Has spent 0 dollars and used about 1hour for the whole thing :).

For others who also have problems with a PC, which won't start, no boot, here is a brilliant check-list, that you could follow and attempt resolving the problems: read this.

Dc7800 SFF won't start

Create an account on the HP Community to personalize your profile and ask a question