Dead computer

We had a power cut on Saturday. We've had them before, but generally they have been momentary blips of less than a minute. This time the power went off, and it didn't seem to want to come back. I called the power company, and was told that yes, there was a fault, and that if it hadn't come back within 4 hours, to call again. As it happened, everything burst back into life within about 50 minutes.

Unfortunately I don't have an Uninterruptible Power Supply. On this occasion, when the power came on my workhorse P3 server came straight back into life and booted fine. My top-of-the-range Athlon 64 (Gigabyte K8VNXP motherboard) machine went bang, and smoke came out of the power supply.

Off I went to Maplin to buy a new PSU. I opted for a 650W unit with plenty of fans. Having fitted it, I thought all would be happier. However, now when I plug the machine in, it spontaneously starts (I don't need to touch the power button). The graphics card information is displayed on the screen, there's a beep, but the BIOS information is never displayed, and the machine starts again. This happens two or three times, then it seems to decide to take a rest, and may pop back into life again a few minutes later for another attempt or two.

I've tried reseating all the cards… I've tried removing the memory and reseating it (plugging it in without memory resulted in multiple panicky beeps, so I guess the motherboard knows that something is going on). I can't figure what is dead. It could be the board itself has suffered damage, or maybe the CPU, or the memory… or even the power switch on the case, I suppose.

I'm looking at going down the route of a new motherboard, but technology has moved on. I've got a range of PCI cards that I'm happy with, so I don't want a PCI-Express board. Socket 754 is no more, so it's a new CPU, and I would like an Athlon 64 X2. I also want something to support Linux. So I'm thinking about an Abit AV8 Third Eye board, which has been discontinued but is still widely available… and I'm counting on my existing RAM being OK. Not sure what else I can do. I'm annoyed, but it is at least partly my fault. I really must get a UPS.

Update: I've cracked it. It's the power switch. Fortunately this means that I don't have to order a new motherboard when the existing one works fine. It does mean that I have to figure out how to wire a new switch into my case, or buy a new one. Suggestions, anyone?

1 thought on “Dead computer”

  1. Hmmmm, I’ve never had to swap a power switch for a computer, but I did replace the power switch in canister vacuum cleaner. It’s a similar problem, and there’s not much to it, other than to decide that you will try. Five years later, the vacuum switch is still working fine.

    The computer power switch is nothing more than a momentary push button. I really don’t think you’ll need to shell out for a new case. I don’t feel ripping mine apart right now, but I imagine the “real” switch is mounted behind the plastic “button”, possibly on a small circuit board. Hopefully, there’s a screw or two that you can remove to pull the assembly.

    If not, I’d start hacking it up from the inside. Plasic cuts easily with a any number of tools. Tools I’ve used in the past include a razor knife, tin snips, hack saw blade, jeweler’s file, etc.

    Now, I think I hear you saying, “How will I ever get it back together if I destroy it? Do I really want to tear up the plastic work?” Sure you do. The worst thing that could happen is that you end up having to buy a new case, which is your *only* choice if you don’t try to repair what you have (for me, it was a whole new vacuum).

    Once you get the switch and/or board assembly out, you’ll have to see what it looks like and try to find a replacement. Ideally, you’ll find an exact replacement, solder it in where the old one comes out, and put it back together with those screws. At the other extreme, there are no screws, you’ve hacked up the plastic, and you can’t aquire an exact replacement. It’s still no big deal. Get any old momentary push button switch and connect it to the two wires (no polarity to worry about).

    If the old arrangement has some circuitry on a board (with more than just foil traces), you can always desolder the old switch (pull it from the board) and connect your new switch with short lengths of wire soldered to the pads on the board where the old switch came out. The old switch may be mounted in more than two holes (it could be a 4 pin device). If so, you need to figure out which ones are the electrical connections and which are just for mechanical support. If you don’t have a meter, just look at the foil traces on the board. Pins that are tied together are not affected by the switch. Pins that are not connected to anything are not part of a circuit.

    Okay, now you’ve got the new switch wired, and you’ve tested it. It’s time to put it back together, but you’ve destroyed some of the plastic. Break out the hot-melt glue gun. This stuff is amazing. You’ll want to try to get the new switch mounted behind the plastic button, so that it works normally. If the spacing doesn’t work out quite right so that the button doesn’t quite reach the new switch, you can glue something to the back of the button. I used a chunk of a rubber pencil eraser (a big handheld one, not the thing on the end of the pencil itself) to fill such a gap in the vacuum cleaner. I cut it to fit very precisely and didn’t need to actually glue it in place.

    If you used a panel-mount switch as a replacement (one with it’s own plastic button head), you can always drill a hole for the new switch in different location. You could also remove the exiting plastic button (maybe by force/breaking) and fabricate a new plate in which to mount the switch.

    Suppose that the old plastic button comes out and leaves a big hole, too big to mount the new switch. You want to cover the hole with some (not too ugly) material and drill a hole for the new switch in this material. You could use a piece of metal (which can be painted), or an old piece of plastic (like the empty bay blanks). Cut this material to the size and shape of the hole and glue it in place with super-glue or hot-melt glue from behind. To get a good fit, you might cut it a little large in the beggining, and then work it with a file until it looks good. Finally, you could glue the old plastic button to the button head on the new switch, if you think it would look better.

    Give it a try!


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