Dell Inspiring 14 3421

[dspok]

Completely short-dead machine.
Changed SIO, machine works well but some keys i. e. enter, p doesn't reponds, also with new replacement. Sometime OS displays "usb device not recognised".

Is it still SIO? Or any other issue?
Every pin of SIO connected well, no doubt.

[BlueMidnight]

Re: Dell Inspiring 14 3421

Sounds like at least one row or column of the keyboard matrix isn't working.

There are only a few possible explanations:

1) Bad keyboard. But you already tried another one, so that seems very unlikely.

2) Bad connection at keyboard connector.

3) Bad trace from connector to SIO.

4) Bad SIO. Possible, but you just replaced it so let's assume it's not this for now.

5) Bad SIO firmware. Really doubt it since it has nothing to do with the original problem.


So I think the best thing to try is to check continuity all the way from the keyboard to the SIO. To do this, use another cable that fits in the connector. If you have a cable with fewer pins, that's okay too. You will just have to shift it around in the connector to test the whole thing.

The row/column pins are pins 2-26 on the keyboard connector and pins 34-43, 47-61 on the SIO.

Put one probe at the end of the cable and the other probe on the SIO. You don't even need to look at the schematic if your meter is set to beep. Just rub the probe slowly and gently along all the possible pins. One (and only one) of them has to beep. Do this for every keyboard pin from 2 to 26. Ignore the other pins.

If you find one that doesn't have continuity to the SIO, then that's the problem. All you have to do is find out where the continuity is lost.


For the USB error, it depends if it does it by itself or if it does it when you plug in something. If it happens when you plug in something, the first thing to check is if any pins in any USB ports are bent. You can also try booting to a Linux live disc to see if it's just a problem in Windows.

If it happens by itself randomly, then you can check Device Manager to see what is missing (i.e. not getting recognized). The only internal USB peripherals are the webcam, card reader, and possibly the WLAN card. Check the internal connections for each. Or unplug them completely and see if the errors go away.

[dspok]

Re: Dell Inspiring 14 3421

Thanks @BlueMidnight
Connector to SIO connection Row/Col ok..
Keyboard connector ok, 3v voltage on key is present..
I checked USB port are ok, 2.0 works but 3.0 doesn't respond.

As 3.0 Rx Tx signal goes and comes from PCH, so is it PCH problem or SIO. I didn't check USB3 voltage though. SIO was popcorned, so I'm confused :-s

[BlueMidnight]

Re: Dell Inspiring 14 3421

Have you tried booting to something else, like a Linux disc, to check the keyboard and USB? Don't want to drive yourself crazy and then find out it was just a software problem. :P

If it's a hardware problem, then I don't really see any other option. Either the keyboard is bad, the SIO is bad (or has bad solder joints), or something in between them isn't making good contact. Bad solder joints would have been the most logical explanation (because it was the repaired area), but it sounds like you checked them already. Still, it couldn't hurt to hit the row/column pins with a soldering iron again. Or in the worst case, try a different SIO chip.

If the USB issue is a hardware problem, it's kind of similar to the keyboard problem. It might be the port, the traces, or the PCH. But the USB lines have protection (U6204, U6205), power filtering (TR6204, TR6207), and power control chips (e.g. U6101, U6102) also. Any of those could cause a problem too.

But *both* USB 3.0 ports acting strange is suspicious. The only things they both connect to are the 3/5V chip and the PCH. Hopefully it's just a software issue or something simple, and not the PCH.