Keyboard Issue - ASUS VL/I-486SV2GX4 v1.7

Hello.

So I have an old 486 DX4 100 that I use as a gaming rig every once in a blue moon, problem is, it got knocked over about 2-3 months ago and the keyboard cable got pulled to the side. Ever since, it will not register the keyboard. I've tried jiggling the jack, but it seems to be tight.

Some other things, the keyboard makes the internal speaker beep, but I don't get any lights from the keyboard - no num lock, no caps, no scroll, nothing. Seems some sort of a signal is being sent, but that's about it. So far I've had this thing apart 8 times and still can't find a solution.

Is there any way I can fix this thing or am I messed? I'm not paying $149.99 for a new motherboard on a computer that's 15 years old and only cost me $20.00 total. Is there any sort of an add-in card that can be found to bypass the issue?

Your post reads as though you've already proven that the motherboard is at fault (e.g. second keyboard shows same symptoms), but your post doesn't actually say that.
What is the story?

Is this an AT connector for the keyboard? The metal shield around the connector is grounded on the motherboard and completes the electrical connection to the keyboard. Break that connection from the shield to the motherboard and the keyboard is dead as a doornail. So while the plug itself might be solid you can still have a problem.

Many motherboards of that era use a socketed i8042 or equilavent to handle communications with the keyboard. You may want to reseat yours as it may have become lose as a result of the fall. Also, if your jack is screwed up, you should definitely consider replacing it with a new jack. It's a $5 repair and soldering job.

Great Hierophant said:

Many motherboards of that era use a socketed i8042 or equilavent to handle communications with the keyboard. You may want to reseat yours as it may have become lose as a result of the fall. Also, if your jack is screwed up, you should definitely consider replacing it with a new jack. It's a $5 repair and soldering job.

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Seconded. I had the same problem a few months ago with a $15 486 tower that I picked up at a junk store. Had an AT port that wiggled slightly, but appeared to have good connection to the motherboard upon visual inspection. Plug a KB in and nothing. I pulled out the soldering station, lifted the old solder, resoldered it, and it's working like a charm ever since. If you have some solder and a soldering pencil laying around, then you've all the tools that you need to complete this job.

It's rather doubtful that you damaged a trace on a simple drop... but reseating any socketed chips might be prudent as well.

Unknown_K said:

Is this an AT connector for the keyboard? The metal shield around the connector is grounded on the motherboard and completes the electrical connection to the keyboard. Break that connection from the shield to the motherboard and the keyboard is dead as a doornail.

Click to expand...

I disagree.

If the keyboard design engineer did their job properly, the shield wire will be only be grounded at one end, either at the keyboard, or at the DIN plug/socket. It's done so that no power supply current flows through the shield wire. All power supply current should be flowing through pins 5 (+5V) and 4 (ground/return) of the large DIN connectors. In this case, if through fault the shield becomes ungrounded, it's not going to stop the keyboard from working - you just end up with an unshielded cable.

In the case of a keyboard where the shield is grounded at both keyboard and DIN plug/socket, the power supply return current will be flowing in both the shield and ground/return wires. If through fault the shield wire becomes ungrounded/open, return current still flows via the ground/return wire.

I have seen the keyboard not work when that shield connection is broken (486/P1 boards), make of it what you will.

Unknown_K said:

I have seen the keyboard not work when that shield connection is broken (486/P1 boards), make of it what you will.

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Okay. So on some motherboards, not all. Putting more thought into it, I can see a possible reason - a shortcut taken on certain PCB designs.

Maverick1978 said:

I pulled out the soldering station, lifted the old solder, resoldered it, and it's working like a charm ever since. If you have some solder and a soldering pencil laying around, then you've all the tools that you need to complete this job.

Click to expand...

I would, first off, consider a cracked solder joint and the above procedure would be my first remedial action.

Four intact pins would be more than enough to secure the jack firmly, but, if one pin isn't making good contact (depending on which pin, of course) it's not going to work.