I have a rather strange problem with a monitor connected via HDMI. The problem appeared a few
months ago. Previously it did not occur in the same configuration. I have a computer with Windows
10 and an NVidia Quadro K620 card connected to the monitor via an HDMI switch, to which, in
addition to the computer, a terrestrial TV tuner and another computer are connected. The switch has
three inputs and one HDMI output (which is goes directly to the monitor). The input on which there
is a signal is automatically selected as active. If there are more active signals, you can select
the input with the button.

It worked very well for several years. And suddenly it turned out that if I turn on the TV tuner
for a moment while using Windows and switch the image to this tuner, and after this switch back to
the computer, I have no image from the computer. I can switch back to the tuner and it works, but
for the computer the monitor says: "No signal".

I thought the switch was broken and disconnected everything and connected the PC directly to the
monitor - no signal. I suspected that the entire computer is broken. I reset it and a welcome image
appeared with several BIOS messages and everything seemed to be working fine. But after a while,
when Windows started loading, the image went out again. No signal. I tried many times (this time
without any switches), with the same result. I connected remotely to the computer - the system
worked normally, I did not find any error messages. Finally, I decided to run Ubuntu Linux (from an
external flash drive). It started - and the image appeared on the monitor. I returned to Windows -
the image was suddenly on as if nothing had happened.

Unfortunately, this turned out to be a recurring problem. Since then, every momentary switch of the
HDMI input, or even momentary disconnection of the cable coming from the computer and reconnection,
causes the HD image from Windows to disappear. But this only applies to HD image; text mode works
(BIOS inital messages) and low-resolution graphics too (spinning dots at the beginning of Windows
loading). The only thing that helps is starting and closing Ubuntu. I have already bought another
HDMI switch, unfortunately the effect is the same. To avoid problems with the image, before
switching the HDMI signal or disconnecting the cable from the computer I have to completely turn
the computer off and turn on only after completely reconnecting the monitor. Otherwise the image
disappears and I have to start Ubuntu and then Windows every time.

This is quite inconvenient, because I cannot switch to another computer or to the TV even for a
moment. It looks more like a Windows problem that switches the card to some strange mode and then
can't initialize the card properly. But I'm not sure and I don't know what to do about it. Maybe
someone knows?

P.

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Piotrne wrote:

I have a rather strange problem with a monitor connected via HDMI. The problem appeared a few months ago. Previously it did not occur in the
same configuration. I have a computer with Windows 10 and an NVidia
Quadro K620 card connected to the monitor via an HDMI switch, to which,
in addition to the computer, a terrestrial TV tuner and another computer
are connected. The switch has three inputs and one HDMI output (which is
goes directly to the monitor). The input on which there is a signal is automatically selected as active. If there are more active signals, you
can select the input with the button.

It worked very well for several years. And suddenly it turned out that
if I turn on the TV tuner for a moment while using Windows and switch
the image to this tuner, and after this switch back to the computer, I
have no image from the computer. I can switch back to the tuner and it
works, but for the computer the monitor says: "No signal".

I thought the switch was broken and disconnected everything and
connected the PC directly to the monitor - no signal. I suspected that
the entire computer is broken. I reset it and a welcome image appeared
with several BIOS messages and everything seemed to be working fine. But after a while, when Windows started loading, the image went out again.
No signal. I tried many times (this time without any switches), with the
same result. I connected remotely to the computer - the system worked normally, I did not find any error messages. Finally, I decided to run
Ubuntu Linux (from an external flash drive). It started - and the image appeared on the monitor. I returned to Windows - the image was suddenly
on as if nothing had happened.

Unfortunately, this turned out to be a recurring problem. Since then,
every momentary switch of the HDMI input, or even momentary
disconnection of the cable coming from the computer and reconnection,
causes the HD image from Windows to disappear. But this only applies to
HD image; text mode works (BIOS inital messages) and low-resolution
graphics too (spinning dots at the beginning of Windows loading). The
only thing that helps is starting and closing Ubuntu. I have already
bought another HDMI switch, unfortunately the effect is the same. To
avoid problems with the image, before switching the HDMI signal or disconnecting the cable from the computer I have to completely turn the computer off and turn on only after completely reconnecting the monitor. Otherwise the image disappears and I have to start Ubuntu and then
Windows every time.

This is quite inconvenient, because I cannot switch to another computer
or to the TV even for a moment. It looks more like a Windows problem
that switches the card to some strange mode and then can't initialize
the card properly. But I'm not sure and I don't know what to do about
it. Maybe someone knows?

P.

Congratulations on all the effort you've put into both surviving the
problem and then analysing it.
When things like this suddenly occur, you probably know as well as I do
that somewhere in the chain there's been a software update (or downdate
(:- ). MS update Windows, all third party people have to update theirs:
some don't, some are dilatory, some have retired.

Try manual updates of all drivers in the loop; manufacturers' websites.

Oh, and a suggestion based on problems I've defeated; plug and unplug
all the HDMI connectors used.

Ed

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On 02/09/2024 18:03:05, Piotrne wrote:

I have a rather strange problem with a monitor connected via HDMI. The problem appeared a few months ago. Previously it did not occur in the same configuration. I have a computer with Windows 10 and an NVidia Quadro K620 card connected to the monitor via an HDMI switch, to which, in addition to the computer, a terrestrial TV tuner and another computer are connected. The switch has three inputs and one HDMI output (which is goes directly to the monitor). The input on which there is a signal is automatically selected as active. If there are more active signals, you can select the input with the button.

It worked very well for several years. And suddenly it turned out that if I turn on the TV tuner for a moment while using Windows and switch the image to this tuner, and after this switch back to the computer, I have no image from the computer. I can switch back to the tuner and it works, but for the computer the monitor says: "No signal".

I thought the switch was broken and disconnected everything and connected the PC directly to the monitor - no signal. I suspected that the entire computer is broken. I reset it and a welcome image appeared with several BIOS messages and everything seemed to be working fine. But after a while, when Windows started loading, the image went out again. No signal. I tried many times (this time without any switches), with the same result. I connected remotely to the computer - the system worked normally, I did not find any error messages. Finally, I decided to run Ubuntu Linux (from an external flash drive). It started - and the image appeared on the monitor. I returned to Windows - the image was suddenly on as if nothing had happened.

Unfortunately, this turned out to be a recurring problem. Since then, every momentary switch of the HDMI input, or even momentary disconnection of the cable coming from the computer and reconnection, causes the HD image from Windows to disappear. But this only applies to HD image; text mode works (BIOS inital messages) and low-resolution graphics too (spinning dots at the beginning of Windows loading). The only thing that helps is starting and closing Ubuntu. I have already bought another HDMI switch, unfortunately the effect is the same. To avoid problems with the image, before switching the HDMI signal or disconnecting the cable from the computer I have to completely turn the computer off and turn on only after completely reconnecting the monitor. Otherwise the image disappears and I have to start Ubuntu and then Windows every time.

This is quite inconvenient, because I cannot switch to another computer or to the TV even for a moment. It looks more like a Windows problem that switches the card to some strange mode and then can't initialize the card properly. But I'm not sure and I don't know what to do about it. Maybe someone knows?

P.

Very similar to the problem I had.
My monitor appears to look for an analogue signal before a digital
signal, if I switch on the tv tuner before the computer it will not
then connect to the computer later. My solution was to make sure the
tv tuner is switched off, switch off the monitor and then switch on
again which should then pick up the digital signal as there is no
analogue signal present.

--
mick

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Ed Cryer wrote:

Try manual updates of all drivers in the loop; manufacturers' websites.

I noticed the problem on April 17. Six days earlier, a Windows "cumulative update" and a graphics
card driver were installed. It is quite possible that it got damaged then (I rarely use the TV
tuner, so I could not have noticed it for a week). I will try to do something with these drivers.
I thought that maybe others had this problem, but did not find anything about it.

Oh, and a suggestion based on problems I've defeated; plug and unplug all the HDMI connectors used.

I did that of course. But it's clearly not a cable or connectors issue. Running Ubuntu solves
the missing image problem immediately without touching any cable.

P.

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mick wrote:

My monitor appears to look for an analogue signal before a digital signal, if I switch on the tv
tuner before the computer it will not then connect to the computer later.

My monitor does the same, but this is not the case. The image from the HDMI input
is displayed correctly from the moment the computer is turned on until the Windows
login screen should appear - then the monitor reports "no signal" and manually switching the inputs between analog and HDMI does not help.

P.

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On Mon, 9/2/2024 1:03 PM, Piotrne wrote:

I have a rather strange problem with a monitor connected via HDMI. The problem appeared a few months ago. Previously it did not occur in the same configuration. I have a computer with Windows 10 and an NVidia Quadro K620 card connected to the monitor

via an HDMI switch, to which, in addition to the computer, a terrestrial TV tuner and another computer are connected. The switch has three inputs and one HDMI output (which is goes directly to the monitor). The input on which there is a signal is
automatically selected as active. If there are more active signals, you can select the input with the button.

It worked very well for several years. And suddenly it turned out that if I turn on the TV tuner for a moment while using Windows and switch the image to this tuner, and after this switch back to the computer, I have no image from the computer. I can

switch back to the tuner and it works, but for the computer the monitor says: "No signal".

I thought the switch was broken and disconnected everything and connected the PC directly to the monitor - no signal. I suspected that the entire computer is broken. I reset it and a welcome image appeared with several BIOS messages and everything

seemed to be working fine. But after a while, when Windows started loading, the image went out again. No signal. I tried many times (this time without any switches), with the same result. I connected remotely to the computer - the system worked normally,
I did not find any error messages. Finally, I decided to run Ubuntu Linux (from an external flash drive). It started - and the image appeared on the monitor. I returned to Windows - the image was suddenly on as if nothing had happened.

Unfortunately, this turned out to be a recurring problem. Since then, every momentary switch of the HDMI input, or even momentary disconnection of the cable coming from the computer and reconnection, causes the HD image from Windows to disappear. But

this only applies to HD image; text mode works (BIOS inital messages) and low-resolution graphics too (spinning dots at the beginning of Windows loading). The only thing that helps is starting and closing Ubuntu. I have already bought another HDMI switch,
unfortunately the effect is the same. To avoid problems with the image, before switching the HDMI signal or disconnecting the cable from the computer I have to completely turn the computer off and turn on only after completely reconnecting the monitor.
Otherwise the image disappears and I have to start Ubuntu and then Windows every time.

This is quite inconvenient, because I cannot switch to another computer or to the TV even for a moment. It looks more like a Windows problem that switches the card to some strange mode and then can't initialize the card properly. But I'm not sure and I

don't know what to do about it. Maybe someone knows?

P.

I would check two things.

1) devmgmt.msc (Device Manager)

I would check the video driver, to see if you are using
Microsoft Basic Display Adapter driver, or whether the
NVidia driver is present.

2) While remoted into Windows 10 (because you cannot see the screen),
use Moninfo from Entechtaiwan, and use the "Real Time" function
to read the EDID, right after the screen goes blank. This would
tell you whether the EDID was being removed, while in service.

https://entechtaiwan.com/util/moninfo.shtm

( https://entechtaiwan.com/files/mi_setup.exe )

This is the site that made PowerStrip, but Powerstrip is discontinued,
but the Moninfo gives a little information (especially about EDID table).

Strictly speaking, if the EDID was not sent to the Windows computer,
it still would have worked. But, the Windows computer would have sent
a 1024x768 image. I do not know if that works on your setup or not.

With a real NVidia driver, that driver is not allowed to send anything
but 1024x768 when the EDID is missing. When the EDID is present, more resolution options will be available.

What the computer relies upon, is impedance detection. It detects
a 100 ohm differential load on R pair, G pair, B pair. That is how the
computer knows a monitor is present. Your display should always
terminate those signals to the computer. As a result, the computer
should always put a signal on the cable. The EDID table being missing,
is an inconvenience, as with the EDID table present and offered from
monitor to computer, the computer can pick the correct (native) resolution.

There is no mechanism, for the computer to stop sending a signal,
except the loss of termination on R pair, G pair, B pair. The idea of
impedance (termination) sensing, is to ensure no signal is radiating
from un-terminated wire or pins.

Pin 1 TMDS data2+ \
Pin 2 >-- 100 ohm termination at lower speeds, the three signals are RGB
Pin 3 TMDS data2− /
Pin 4 TMDS data1+ \
Pin 5 >-- 100 ohm termination
Pin 6 TMDS data1− /
Pin 7 TMDS data0+ \
Pin 8 >-- 100 ohm termination
Pin 9 TMDS data0− /
Pin 10 TMDS clock+ \
Pin 11 >-- 100 ohm termination <=== on higher speed HDMI, this is a data signal
Pin 12 TMDS clock− /
Pin 13 Consumer Electronics Control (CEC)
Pin 14 Utility/HEAC+
Pin 15 SCL (I2C serial clock for DDC) \____ EDID table interface
Pin 16 SDA (I2C serial data for DDC) /
Pin 17 Ground
Pin 18 +5V (up to 50 mA)
Pin 19 Hot plug detect, HEAC−

Paul

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On 9/2/2024 1:03 PM, Piotrne wrote:

This is quite inconvenient, because I cannot switch to another computer
or to the TV even for a moment. It looks more like a Windows problem
that switches the card to some strange mode and then can't initialize
the card properly. But I'm not sure and I don't know what to do about
it. Maybe someone knows?

I can't explain it, but I have something similar. I built a new
computer in January and installed Win10. I'm using the onboard
Intel graphics. First via HDMI and now via DisplayPort. In both
cases, if I turn on the computer before turning on the monitor,
the computer doesn't see it. Like you, I have to reboot. As long
as I turn on the monitor first it's fine. Sleep mode is also no
problem.

The only thing I can guess is that the newer BIOS is designed
differently than past BIOSes and can't switch display after a
certain point. But I haven't found an explanation. It has nothing
to do with the OS and I've found no relevant setting in BIOS setup.

--- SoupGate-Win32 v1.05
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I managed to solve the problem, at least temporarily. I downgraded the NVidia driver
from version 555.99 (from June 4, 2024) to version 552.86 (from July 29, 2024). The version 555.99 is not WHQL certified, the 552.86 is - and works fine. I can switch
now (again) between HDMI inputs and after returning to Windows I still have the image.

I really don't know why I had the version 555.99 - I didn't install it manually.
And the problems started in April, probably with another non-working driver version.
Apparently Windows Update replaces them without asking...

P.

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On 9/17/2024 3:05 PM, Piotrne wrote:

I managed to solve the problem, at least temporarily. I downgraded the
NVidia driver
from version 555.99 (from June 4, 2024) to version 552.86 (from July 29, 2024).
The version 555.99 is not WHQL certified, the 552.86 is - and works
fine. I can switch
now (again) between HDMI inputs and after returning to Windows I still
have the image.

I really don't know why I had the version 555.99 - I didn't install it manually.
And the problems started in April, probably with another non-working
driver version.
Apparently Windows Update replaces them without asking...

P.

There are ways of stopping Microsoft from messing with a specific device driver. Here is one method but I believe there are others.

A quick Google search for "How do I stop Windows 10 from updating video drivers?", minus the quotes should give you more information.

Right-click the Start button and select Control Panel.
Make your way to System and Security.
Click System.
Click Advanced system settings from the left sidebar.
Select the Hardware tab.
Press the Device Installation Settings button.
Choose No, and then press the Save Changes button.

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