Painted into a corner, I fear

November 2, 2009 9:30 PM

Did I just brick this computer?

This hand-me-down K7T266 based PC had previously been diagnosed with a faulty PS/2 keyboard port, and the owner had been advised that this was not worth fixing and that he should just use a USB keyboard, which he was doing. Windows XP Home ran just fine this way. However, there was no obvious way to get to the BIOS settings as the BIOS didn't recognize the USB keyboard, and thus no obvious way to boot from CD.

No problem, says me cheerfully; we'll just reset the CMOS settings, which should make it enable legacy USB keyboard support from powerup, and let us get to the BIOS settings screen using your USB keyboard. So I do the usual jumper dance.

Bad move. On startup, it now announces that that the CMOS settings are wrong (fair enough) and prompts to press F1 to enter Setup or F2 to load defaults and continue - but it still won't accept USB keyboard input, so it just sits there. It never gets as far as trying to boot, either from disk or anything else.

We tried plugging in a PS/2 keyboard but that does, indeed, not work. We also tried plugging the USB keyboard into one of the mobo USB ports after I noticed that it was attached to a PCI add-on card; no change. The owner says that he seems to recall being told that the mobo USB ports were faulty as well, which is why the add-on card was installed. Sigh.

So it seems my helpfully helpful help has cost him the use of his old computer. Anybody got any good ideas for getting it going again, or have I just obligated myself to find, supply and fit a replacement K7T266 mobo?

posted by flabdablet to computers & internet (19 comments total)

It sounds like toast to me, unless the PS/2 port can be repaired for less expense/trouble than replacing the whole mobo.

Could it just be that the connector needs to be resoldered? It's a really easy job.
posted by Netzapper at 9:37 PM on November 2, 2009

Can't you reset the CMOS?
posted by stresstwig at 9:42 PM on November 2, 2009

Err, I meant by removing the battery temporarily.
posted by stresstwig at 9:43 PM on November 2, 2009

Not really looking forward to taking everything apart just to inspect the pins under the PS/2 connector, but will certainly do that before seeking a replacement mobo.

How often have you seen PS/2 port solder joints fail?
posted by flabdablet at 9:43 PM on November 2, 2009

Jumper. I mean jumper. http://www.wikihow.com/Reset-Your-BIOS
posted by stresstwig at 9:44 PM on November 2, 2009

stresstwig, doing the usual jumper dance to reset the CMOS is exactly what got me into this corner in the first place. Before I did that, the PC would at least boot from HD and run Windows successfully (the USB keyboard works fine in Windows, just not in the BIOS). Since I did that, it just sits there complaining that its CMOS settings are wrong and waiting for a keypress that it can't detect.

Thanks, though, for making me feel a little less like what I tried was the act of a champion dill :-)
posted by flabdablet at 9:47 PM on November 2, 2009

Socket A motherboards are cheap yo:

http://computers.shop.ebay.com/Motherboards-/1244/i.html?CPU Socket Type=Socket A
posted by tresbizzare at 10:02 PM on November 2, 2009

Ah, I thought you had just changed the single setting somehow. carry on.
posted by stresstwig at 10:08 PM on November 2, 2009

carry on

That's the idea. How is the question :-)
posted by flabdablet at 10:10 PM on November 2, 2009

Try plugging the PS/2 keyboard into the mouse port. Both ports are PS/2 and the BIOS should recognize devices on either port.
posted by JackFlash at 10:17 PM on November 2, 2009

JackFlash, I forgot to mention that I'd actually tried that already, with no success.

In case this helps pin down the actual PS/2 fault: the three lock LEDs (num lock, caps lock, scroll lock) on the PS/2 keyboard flash briefly as the computer powers up, but subsequently tapping Num Lock doesn't toggle the LED. It looks to me as if the keyboard has power but no working data connection.
posted by flabdablet at 10:30 PM on November 2, 2009

Oh yeah, and the PS/2 keyboard we used is one that was working fine on his new computer.
posted by flabdablet at 10:31 PM on November 2, 2009

I had this exact same thing happen to me on an old motherboard with a fried PS/2 keyboard port. I had to throw it away. There are PS2 PCI cards that may help, but a replacement board from eBay would probably be cheaper.
posted by zsazsa at 10:39 PM on November 2, 2009

Sorry, but you're very likely boned. If the onboard PS/2 and USB ports are shot - and it certainly seems like they are - there's no way out of this that I can think of. Even finding an identical m/board pc and swapping out the BIOS chip after configuring the settings on the donor board wouldn't work, as you'd likely still reset to default settings sans battery power, and need keyboard function. Knowing that the onboard USB slots were shot *before* you started would have hopefully stopped you making the mistake, so you're not entirely at fault here. (plugin USB boards won't work for BIOS level USB access)

On the plus side, once you're started losing southbridge chip function, there's a decent chance the hard-drive controller was next, as the K7T266 didn't have a good reputation even when it was new, so it was living on borrowed time anyway.

There is one other possibility; after a bit of googling, if it's an original K7T266, rather than a pro; when the bus speed exceeded 138 MHz, the USB ports stopped working. If you hard powercycle it a few times during BIOS boot, it might reset to failsafe speed settings and the onboard USB may kick back into life. Failing that, if you had same realllllly slow DDR....
Bit of a hail mary, but worth a go.

With regards replacement:

If you can find a replacement motherboard based on the same southbridge chipset (I believe a VIA VT8233) then you won't bluescreen the existing windows from an incompatible ide controller, but I'd still stick the hard-drive in another pc first and dump off his data in case. That's assuming he's not using the onboard promise raid controller, in which case, good luck!

If he is using the via southbridge, something like this ASRock K7VT6 refurb should be close enough for windows xp to 'just work'.
posted by ArkhanJG at 10:47 PM on November 2, 2009 [1 favorite]

I would try removing the battery as stresstwig suggested just in case it does something that a jumper reset does not. Just leave the battery out when you power up. You may get a battery warning message but it may re-enable either the USB or PS/2 ports.
posted by JackFlash at 10:48 PM on November 2, 2009

Might be able to get thru the CMOS error if you disconnect any and all peripherals including drives.
posted by sophist at 11:57 PM on November 2, 2009

If the keyboard has an F-shift (or Function-Lock) key, try holding (or toggling) it before hitting F1. If the BIOS is even minimally USB-keyboard-aware & has enabled legacy USB support (as you expected it to when resetting the CMOS), this may help - often, USB keyboards are not set into "Function keys as, y'know, actual function keys" mode until Windows starts taking over.
posted by Pinback at 12:49 AM on November 3, 2009

PCI PS2 card wont work in BIOS btw. Probably just have to get an old socket A mobo and be done with it.
posted by damn dirty ape at 7:47 AM on November 3, 2009

Some help here, maybe? Different mobo, but maybe you can use a similar technique.
posted by jefeweiss at 8:37 AM on November 3, 2009