Keyboard Diagnosis?

Is there a KVM involved in this?

Best regards, Spehro Pefhany

What model number keyboard? And what is the offending system?

It may be more than a simple power problem (I'd just expect nothing to work). Its probably a failure signal either from the keyboard processor itself or the PC's BIOS

Yes :-(

...Jim Thompson

Belkin F8E-206-USB. "Offending system" is IOGear HCS1734 KVM.

...Jim Thompson

That happens during startup POST and, IIRC, when the KB is plugged in.

Lemme see...(if nothing follows, it stopped working :-p )

Ahyup, does. Dang, numlock turned off...that's better...

I think some KBs just don't do it.

Tim

-- Deep Fryer: A very philosophical monk. Website @

Could be a "hot key" mode. Does pressing ESC make it go away?

Best regards, Spehro Pefhany

No. And IOGear "support" is playing dumb, only will say their keyboards work with their KVM's

...Jim Thompson

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Sounds like a bad keyboard. Over current reset. Maybe the KVM cant supply the current needed.

Cheers

Or a dirty POR on the keyboard itself, after which it kind of "hangs".

I got it to work by resetting the KVM WITHOUT its own power unit unplugged, so that power only came via the host PC's.

Maybe it IS a bad (as in too high a current) keyboard??

...Jim Thompson

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Hmmm, Sounds like the KVM power supply might have been flakey. Cheers

If you have a digital scope just hang it on the USB supply to the keyboard and set the trigger to normal, trig level to 90%, time base to

I guess you meant "without the KVM supply plugged in". Maybe it comes up a bit sluggish and the keyboard POR is lousay, as Archie would have put it.

It's amazing how only a few people are able to design a proper POR. What I've done at times (shhh, don't tell anyone I went that low) is to take the lone electrolytic in the offending unit out and replace it with a much smaller one. But never on anything mission-critical.

I'm going to lash up a USB "break-out" extender, so I can watch such things. It certainly looks like a "surge" oscillator.

Yep. I got my double negatives up in force ;-)

I have some really slick POR's. You don't do chips or I'd share with you.

...Jim Thompson

That would be nice. And no, I am not planning to do any chips. Might get pulled into one but then they usually want me to re-design a nasty area such as a pulser or an amp. I'm a board level guy. Debugging a flex with tons of 0402 right now. Man, that gets difficult with age.

My PORs are pretty simple, just transistors, diodes, resistors and a cap. The cap is rapidly discharged below threshold should the power rail drop down. That way it'll hold in reset for a while when it comes back up. Works a lot better than what's found on many uC.

I'll send you a sample.

...Jim Thompson

OK, I was thinking of a PC as a host system. Sounds like the KVM is continually rebooting. Many keyboards blink their LEDs upon startup, but no PCs can cycle so quickly that one would describe a repetitive blink.

Do you have a powered USB hub lying around? Try putting that between the KB and KVM.

Never mind. Take a look at the Belkin spec page:

"Our ClassicKeyboard only works with MS drivers. Our drivers do not work in Windows XP".

To me, this means that this keyboard needs to talk to specific drivers instead of being some sort of generic USB keyboard device. I'll bet that the KVM doesn't support whatever it is that the keyboard is expecting.

Sounds like nonsense to me. The keyboard plugs directly into USB and works just fine on my XP machine, has for a year.

But your powered hub suggestion is excellent. My thought is that the keyboard pulls more power at start-up than the KVM can supply.

...Jim Thompson

Well, its Belkin's nonsense, not mine. It does suggest that there may be driver incompatibility issues, exacerbated by the fact that even they don't know which systems their own products work on.

That'll eliminate the power supply issues. USB power compatibility is pretty well defined and I didn't see whether the keyboard requires more than 100mA or the KVM is limited to that level. Absent anything in the spec., you could make a USB cable that breaks out the +5V line and see what it draws.