[SOLVED] Dell Dimension C521 will not start up

sleighedalive · 08-24-2008, 04:34 PM

My son's computer was working fine one day, he tried to turn it on the next day and it would turn on.

There is nothing on the monitor at all, the fans constantly run, the light on the power switch is a solid amber and none of the diagnostic lights are illuminated. Also nothing connected to any of the USB's has any power.

I have checked the voltages on the power supply connector and all appear to be OK.

Any idea anyone?

Doby · 08-24-2008, 07:39 PM

If your sure the psu is good its most likely a motherboard gone bad

sleighedalive · 08-25-2008, 05:02 AM

There is a label on the side of the Power Supply that lists the following voltages: +5V
+5V (FP)
+12V
-12V
+3.3V

So with the mains lead connected i switched on the computer and i measured the following voltages on the connecter leading from the Power Supply whilst it was plugged into the Mother Board.

All Red wires measured 5V
The Violet wire measured 5.1V ( which i'm assuming is the 5V (FP) )
The White wires measured +12V
The Blue wires measured -12V
The Orange wires measured 3.3V
There is also a Grey and Green wire on the connector, i'm not sure what they are for but my guess is they are associated with the power on switch.

So yes i am fairly confident that the Power Supply is good is there any checks i can do to confirm its the Mother Board. Would it be possible to repair. Is there a common fault. I have access to common components like Resistors and Capacitors and i am pretty good with a soldering iron. Any advice would be greatly appreciated.

Wrench97 · 08-25-2008, 04:22 PM

When when you push the power button do the 4 Diag lights on the back do anything?
You could try a CMOS reset.
http://support.dell.com/support/edoc....htm#wp1062024

Diag lights http://support.dell.com/support/edoc....htm#wp1064555

sleighedalive · 08-26-2008, 01:54 PM

On this machine the diagnostic lights are on the front above the Power On switch and they do nothing at all.

With the power off i linked together both pins on the RTCRST jumper for 5 secs, removed the link and tried to reboot. No change.

Wrench97 · 08-26-2008, 02:08 PM

No diagnostic lights and a good power supply is indicative of a bad motherboard, and Dell motherboards are proprietary meaning a standard ATX board won't line up in the case correctly.

sleighedalive · 08-27-2008, 04:37 PM

Whats the chance of it been the processor?

I'm a little bit worried about buying a new motherboard and plugging my existing processor into it. If its the processor that is faulty could it damage my new motherboard.

Wrench97 · 08-27-2008, 04:44 PM

It's possible but unlikely to damage the board it usually works the other way around, the motherboard damages the cpu due to overvoltage.

sleighedalive · 08-28-2008, 02:44 PM

Think i might purchase a new mother board. Is there a step by step guide anywhere for replacing a motherboard and getting the pc up and running again.

Wrench97 · 08-29-2008, 12:50 AM

Yes > http://techreport.com/articles.x/13671

But be aware with a Dell you need to a Dell board because a standard atx motherboard won't fit properly.

sleighedalive · 09-10-2008, 03:48 PM

Fitted new Motherboard and computer now working ok. Thanks for everyones help.

Wrench97 · 09-10-2008, 03:55 PM

Good to hear.

Doby · 09-10-2008, 05:48 PM

Glad your all fixed

Bloomington · 01-24-2009, 04:16 PM

I am also facing the same problem, I checked the power supply other parts and looks like all are working fine. I am looking for buying the new mother can you please let me know where did you buy your mother board? Thank you.

sleighedalive · 01-25-2009, 06:14 AM

I bought my mother board from ebay seller dellkid1. It cost me £41 + £12 P+P.

Wrench97 · 01-25-2009, 06:27 AM

There are a couple of different C521 Motherboards the UT266, HY175 and I think a YY821
here is the UT266> http://www.iso-technologies.com/shop...php?prod=UT226

hlaplante · 08-19-2009, 10:10 AM

Quote:

Originally Posted by wrench97

There are a couple of different C521 Motherboards the UT266, HY175 and I think a YY821
here is the UT266> http://www.iso-technologies.com/shop...php?prod=UT226

can u buy it off that site because its only 89 bucks

btw sorry its been a year since this has had a post but still i have the same problem and hope to figure this out and y it does it

Wrench97 · 08-19-2009, 11:26 AM

Yes you can but it from them, make sure you have the UT266 board first.

hlaplante · 08-20-2009, 07:58 AM

Quote:

Originally Posted by wrench97

Yes you can but it from them, make sure you have the UT266 board first.

damn my is a hy175 do they replace motherboards if u have a warrenty?

Wrench97 · 08-20-2009, 11:59 AM

If it's still under the base warranty or if you have the extended warranty it will be covered.