To fuse or not to fuse???

[dmc]

I have a workstation that is dead!
I have tried 3 power cords I know are good
and 2 wall sockets in totally different
offices.The switch on the back of the computer
is on! and there is no sign of life, no fan
turning, no hard disk moving, no beeps,just
one light on the front of the unit. Isn't there
a fuse in the power unit that can be replaced?
I even tried removing the nic card(had that happen
once where a bad card locked up a computer)
The power button on the front of the computer
has no effect on the situation! THANKS in ADVANCE
for any suggestions!

[Randy_tx]

I'm not aware of a fuse on a power supply.....but hey, they only cost about $25-30 and if it's an ATX style power supply, it only takes about 5 min. to change it out http://www.PCGuide.com/ubb/biggrin.gif

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Will XP save Me ?

[tjaymadison]

The (semi) good news is that there may be a fuse inside the power supply. The (semi) bad news is that many times it's soldered in place. If you do open it up, BE CAREFUL! As with a monitor, you can get a shock even after the unit has been unplugged and off for a while. Those big capacitors hold a charge that can surprise you. Once you open it up, follow the old TV servicemen's method -- keep one hand in your pocket. http://www.PCGuide.com/ubb/biggrin.gif

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"When I nod my head, hit it with the hammer."
(Moe, holding nail, to Curly, holding hammer)

[mjc]

I'm with Randy on this one, tracing down a problem inside a power supply is usually more bother than it is worth, considering the prices of them these days.

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mjc
Links list:Computer Links (http://www.fortunecity.com/skyscraper/highrise/11/index.htm)

468th Rule of Aquistion: Debugging of software is foolish, there is much profit in updates and upgrades.

[GROGSTER]

Hi!

The major problem with pretty much all computer PS units, is the fact that they employ switchmode power regulation.
In a nutshell, this means that there is no transformer isolation from the mains.
There is a "Hot" side and a "Cold" side of the PCB.
The Hot side is at mains potential(either 115vAC or 230vAC), and is very lethal - it will have NO hessitation in killing you if you touch it.

The Cold side is the low voltage side - the 12 and 5 volt rails and a collection of GND connections(the black wires from the power supply).

As was pointed out, the capacitors in these supplies are really dangerous, and you must be very careful indeen when working with a computer PSU.

Generally, you have the mains come into the supply, is rectified to high-voltage DC, and applied to these capacitors.
You can have a potential DC voltage of up to 300v+ on a unit using a 230vAC input voltage, and 300vDC will have no hessitation in escorting you into the next world!!!
http://www.PCGuide.com/ubb/biggrin.gif

With respect to your problem, If there is no activity at all with the power switch on, then I suggest that you try another PSU, as this is probably the cause.
If things are completely dead when you switch them on, then you must look for some sort of life from the PSU.
Try connecting a voltmeter to the power leads for the devices that the PSU feeds(like hard-drives, CD-ROM's etc).
You should have 12v across the yellow and a black, and 5v across the red and a black.

If you get no voltage reading at all, the only other possiblility is that the power switch itself is faulty.
You could try measuring for mains voltage on both sides of the power switch with the switch on, and power applied.
BE VERY CAREFUL if you do this - this is not work for someone who has no care for safety, or no respect for the mains...

If there is voltage on both sides of the power switch, but no voltage on the power leads to the devices(the 12 and 5 volt wires - yellow and red), then there is definetly a problem inside the PSU.

Best solution is replacment, cos servicing one of these is not economical.

Good luck.
http://www.PCGuide.com/ubb/smile.gif

G.

[Randy_tx]

My point is this........you can spend $100 worth of time on a $25 component if you wish......but if you have work to do, it's ALWAYS better to replace inexpensive computer components than try to fix em. Even fixed, it's still an old component http://www.PCGuide.com/ubb/biggrin.gif

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Will XP save Me ?

[GROGSTER]

I agree.

You are much better to replace if time is important.

G.