Benq LCD with Belkin KVM. No signal detected.

[Patrick Finnegan]

I just bought a Belkin 2-Port KVM Switch with Audio Support and
Built-In Cabling, PS/2. The manual says it supports LCD monitors with
the use of an adapter cable. I connected an IBM ThinkPad laptop and a
PC desktop to the KVM which is hooked up to my BenQ FP91G LCD monitor.
The laptop desktop is displayed but I get "no signal detected" when I
switch to the PC. The strange thing is the PC used to work with the
BenQ before I set up the KVM but now the "no signal detected" message
appears when I connect the BenQ directly to the PC. I suspected a
graphics card problem so I bought the PC down to the local service
centre and we connected an LCD screen. The PC booted and the display
was fine.

So it would seem that connecting the KVM has caused a problem which is
specific to the BenQ and the PC. I just wonder if I need that adapter
cable mentioned in the manual. I didn't think so because the laptop
which has an LCD screen displayed fine on the BenQ. Are the adapters
really necessary and where can I get one? Couldn't find anything on
the net.

The motherboard on the PC is an Asus A8V. I have no idea what the
graphics card is.

Regards.

Patrick.

 

[kony]

I just bought a Belkin 2-Port KVM Switch with Audio Support and
Built-In Cabling, PS/2. The manual says it supports LCD monitors with
the use of an adapter cable. I connected an IBM ThinkPad laptop and a
PC desktop to the KVM which is hooked up to my BenQ FP91G LCD monitor.
The laptop desktop is displayed but I get "no signal detected" when I
switch to the PC. The strange thing is the PC used to work with the
BenQ before I set up the KVM but now the "no signal detected" message
appears when I connect the BenQ directly to the PC. I suspected a
graphics card problem so I bought the PC down to the local service
centre and we connected an LCD screen. The PC booted and the display
was fine.

This KVM is analog or DVI? What is this adapter cable it's
supposed to need? IIRC, your monitor has both DVI and
analog, so IF the KVM is analog, there should be no adapter
needed (Unless I'm misunderstanding the situation).

Had the desktop previously used DVI or analog? Is it
possible that it is now using analog with too high a refresh
rate? The max refresh rate is probably 75Hz or lower, I'd
try 60Hz.

So it would seem that connecting the KVM has caused a problem which is
specific to the BenQ and the PC. I just wonder if I need that adapter
cable mentioned in the manual. I didn't think so because the laptop
which has an LCD screen displayed fine on the BenQ. Are the adapters
really necessary and where can I get one? Couldn't find anything on
the net.

The motherboard on the PC is an Asus A8V. I have no idea what the
graphics card is.

If it's an analog video card output, an analog KVM, and the
KVM cable is connected to the analog input on the monitor,
it should work - unless the refresh rate is set too high.
However, it might be possible that when you use the KVM to
switch systems, for that brief moment there is no video
going to the monitor and that tricks the monitor into
thinking it should switch to DVI mode. See if that is
happening by pressing the Input Select button on your
monitor when no signal is detected (Maybe the "Exit"
button?) and checking whether it is set to DVI- and choosing
Analog (might be called D-Sub) if not set to that (and
assuming again that all your parts are analog as described
previously).

If the problem is that the monitor is switching to DVI mode
automatically when the signal is interrupted momentarily,
then check your monitor manual to determine if the DVI port
is a true DVI-I or just DVI-D functional. I mean if the
analog signal can be input through the DVI connector then it
might work acceptibly. Otherwise (and what I'd expect) is
you'd need to convert the signal to DVI digital
transmission, or use a different monitor, but this is too
premature a speculation until there is more info to go on.

 

[Patrick Finnegan]

This KVM is analog or DVI? What is this adapter cable it's
supposed to need? IIRC, your monitor has both DVI and
analog, so IF the KVM is analog, there should be no adapter
needed (Unless I'm misunderstanding the situation).

Had the desktop previously used DVI or analog? Is it
possible that it is now using analog with too high a refresh
rate? The max refresh rate is probably 75Hz or lower, I'd
try 60Hz.

Thanks for your detailed reply Kony.

The desktop has always used analog with the monitor being plugged
directly into the d-sub port on the BenQ. I did set the refresh rate
higher than 60Hz when I installed MS Flight Simulator. The BenQ also
has a DVI port which is un-connected. I don't have a DVI cable to test
the DVI port.

The display on the BenQ when connected to the lappy is 1024@768 @ 60Hz.

I reconnected the monitor directly to the PC but still get the "no
signal detected" message. The menu options on the BenQ are accessed
via the "enter" button but don't seem to be available in the "non
signal detected" mode. They appear when connected to a "live" display
such as the lappy. The main issue now is that the BenQ will not
display when connected directly to the desktop. I don't know whether
this was caused by by connecting two machines with different display
rates to the BenQ via the KVM. Anyway the KVM will never work until I
get the direct connection working. Given that we tested the PC
graphics card with another monitor and it worked is there any way we
reset the BenQ so it works with the PC.

Thanks.

Patrick.

 

[kony]

The desktop has always used analog with the monitor being plugged
directly into the d-sub port on the BenQ. I did set the refresh rate
higher than 60Hz when I installed MS Flight Simulator.

Set it to 60Hz. I don't recall the max for that monitor but
it's definitely 85Hz or lower, probably 75 or 70Hz or lower.
It definitely supports 60Hz. With DVI this is a non-issue
but with analog it has to be a refresh rate the monitor
suppports- but it does not necessarily have to be same
refresh rate or resolution the laptop uses.

The BenQ also
has a DVI port which is un-connected. I don't have a DVI cable to test
the DVI port.

The display on the BenQ when connected to the lappy is 1024@768 @ 60Hz.

I reconnected the monitor directly to the PC but still get the "no
signal detected" message. The menu options on the BenQ are accessed
via the "enter" button but don't seem to be available in the "non
signal detected" mode. They appear when connected to a "live" display
such as the lappy. The main issue now is that the BenQ will not
display when connected directly to the desktop. I don't know whether
this was caused by by connecting two machines with different display
rates to the BenQ via the KVM. Anyway the KVM will never work until I
get the direct connection working. Given that we tested the PC
graphics card with another monitor and it worked is there any way we
reset the BenQ so it works with the PC.

Reboot the desktop in safe mode, while you are watching it
on the KVM. Before windows loads the video driver it should
be in 640x480 an 60Hz, so see if it has video up until
windows loads, and then if it keeps it in safe mode. If it
does, while in safe mode set the refresh rate lower. Are
you using the monitor driver (INF file) on the desktop?
That should limit the refresh rate choices available to
those the monitor supports, IF windows is working as it
should.