Jim Thompson wrote:

On Mon, 30 Jul 2007 22:37:43 GMT, Joerg
wrote:


Martin Riddle wrote:


"Jim Thompson" wrote in
message ...


What does it mean when all three LED's (Num Lock, Caps Lock and Scroll
Lock) on a keyboard blink together?

It doesn't happen on all the systems I plug it into, just one.

I'm guessing maybe the one host system can't support the keyboard
power ????



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


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.


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
100msec/div or so. That should show any collapse when you plug it in.


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


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.

--
Regards, Joerg

http://www.analogconsultants.com