KVM Switch

  • Thread starter Thread starter philo 
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philo 

I have a Tripp_Lite 2 port KVM switch that has worked fine for many
years. The switch automatically detects which computer I initially turn on.

Recently I replaced one of my machines with another of similar
specifications. Now the switch no longer detects which machine has been
turned on...it merely stays in the previous position.
(I have to manually switch it prior to bootup)

All machines have nVidia video with standard VGA output.
They use standard ps/2 mice and keyboards

Just curious as to what is going on.
 
philo said:
I have a Tripp_Lite 2 port KVM switch that has worked fine for many
years. The switch automatically detects which computer I initially turn on.

Recently I replaced one of my machines with another of similar
specifications. Now the switch no longer detects which machine has been
turned on...it merely stays in the previous position.
(I have to manually switch it prior to bootup)

All machines have nVidia video with standard VGA output.
They use standard ps/2 mice and keyboards

Just curious as to what is going on.
Click to expand...

At a guess, both machines power the PS/2 ports with +5VSB.

Try turning off the power at the back of *both* computers.
Then, turn on the power at the back of just one computer,
push the front power button and boot. Did it detect
that properly ?

Years ago, PS/2 ports were powered via a jumper block. The
user could set the jumper block to +5V or +5VSB. The +5VSB
stayed on all the time, defeating the auto-detect of
your KVM. Whereas, machines using +5V (like mine), the +5V
is only present when you push the button on the front of
the PC. And, that gives an opportunity for detection of
activity.

Modern motherboards, they removed all the 1x3 headers
for power selection. Now the user has no choice. All
ports (PS/2 and USB) are powered by +5VSB. And switching
off at the back, is how you remove power in that case.

If all you do, is use the front ("soft power") button,
well, that doesn't cycle the +5VSB. And then the KVM
doesn't think anything happened.

Paul
 
At a guess, both machines power the PS/2 ports with +5VSB.

Try turning off the power at the back of *both* computers.
Then, turn on the power at the back of just one computer,
push the front power button and boot. Did it detect
that properly ?

Years ago, PS/2 ports were powered via a jumper block. The
user could set the jumper block to +5V or +5VSB. The +5VSB
stayed on all the time, defeating the auto-detect of
your KVM. Whereas, machines using +5V (like mine), the +5V
is only present when you push the button on the front of
the PC. And, that gives an opportunity for detection of
activity.

Modern motherboards, they removed all the 1x3 headers
for power selection. Now the user has no choice. All
ports (PS/2 and USB) are powered by +5VSB. And switching
off at the back, is how you remove power in that case.

If all you do, is use the front ("soft power") button,
well, that doesn't cycle the +5VSB. And then the KVM
doesn't think anything happened.

Paul
Click to expand...



OK I reset everything and that made no difference but thanks for the
suggestion. This is not a big deal as I mainly use only one of the
machines and to push the "select" button is no big deal if I need to
boot the other one first.
 
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