Dimension 4550 won't power up

ziti49

It would seem that the power supply has failed.

You can check the power supply, by unplugging the cord from the power supply, hold the power button in for about 15/20 seconds, open the case, unplug the 20-pin connector from the motherboard and jump the Green wire to one of the Black wires, reconnect the power cord and if power supply fan and hard drive runs, then the PSU should be good.

Note: Do not remove any wires from the plug, use a small piece of wire or a paper clip as a jumper.

Bev.


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Message Edited by ziti49 on 12-17-2007 05:02 PM

No life at all generally means the PSU failed. If getting a new one, don't just get any old 250 watt one. That Dell PSU is equal to a ~345 watt PSU, and isn't exactly a cheap quality one either. Regardless, the motherboard is standard ATX as far as PSU connections go, so most will work. I don't know if the 4550 has an open back, so if not, you may need to use tin-snips or something to cut the back away for it to fit, since most retail PSUs have an on/off switch which the Dell case won't have an opening for. I did this on my Optiplex GX270 and it's not that hard, and I presume the warranty on that 4550 is out anyway.

ziti49

The D-4550 can use most standard generic ATX power supplies, with either a 20-pin or 20+4-pin main motherboard connector and without on/off switch.

If you use a PSU with the switch, then you will have to modify the back panel of the case for it, by cutting a hole for the switch.

A D-4550 compatible power supply can be purchased from either Dell Spare Parts, or from here, for $39.

Bev.


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ziti49

Sounds doable. :)

Bev.


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ziti49

What is the reading of the four diagnostic lights on the back panel?

Bev.


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ziti49

As you have a know good power supply and the system still does not boot, remove power cord, hold power button in to discharge the residue power.

Remove all the PCI cards, the video card [if applicable], memory, all peripherals, disconnect the data and power cables to all the drives, then check that the front panel cable is connected to motherboard, with nothing else connected to the system, except the power cable, power the system on.

If you do not get any beep codes or no diagnostic lights on the front panel, then it would appear that motherboard has died.

Bev.



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Bev, thank you for your many troubleshooting suggestions in an attempt to rescue my sick PC. I disconnected everything and removed all of the cards and memory. Still no power or diagnostic lights. I think I'll probably opt for a new PC over a new motherboard at this point. Thanks for all of your help. Is there any way to test that it's not the front power switch? Would the health of the backup battery have any effect?

Have a very similar problem, strangely my dimension 4550 starts posting when I removed my mainboard battery. I bought a new one but when I put it in, the the PC seems dead. Removing it it starts posting. With the battery on board the diagnotic LEDs on the back just swithched on very shortly when I plug in the power cord. Pressing the power button results in nothing ! Removing the battery lets the pc starting with the normal bios-procedure and looking for the IDE-devices. Right now I´m a bit clueless but seems to have something to do with the bios/settings.

So, finaly. It was the flat-cable connecting the power switch + usb.....from the front with the motherboard. connection problem. Now it´s fixed. pc powers up without problems.