HDMI problem

Discussion:

HDMI problem

(too old to reply)

Seymore4Head

2018-03-28 11:54:05 UTC

I use two monitors. I have one monitor with HDMI and another monitor
that uses DVI. The HDMI is primary.

I was using the computer and both monitors went blank. I found the
problem. My dog chewed the plastic off the HDMI end next to the
computer.

I replaced the HDMI cable and neither monitor came on. I pulled out
the Graphics card.

I can plug the DVI into the mobo and it works. When I try to plug in
the HDMI the second monitor switches from primary to secondary, but
the HDMI monitor won't come on. I can unplug the HDMI and the other
monitor becomes primary again.

How do I get both monitors working again and then how do I tell if my
Graphics card is bad?

SC Tom

2018-03-28 13:42:58 UTC

Permalink

Post by Seymore4Head
I use two monitors. I have one monitor with HDMI and another monitor
that uses DVI. The HDMI is primary.
I was using the computer and both monitors went blank. I found the
problem. My dog chewed the plastic off the HDMI end next to the
computer.
I replaced the HDMI cable and neither monitor came on. I pulled out
the Graphics card.
I can plug the DVI into the mobo and it works. When I try to plug in
the HDMI the second monitor switches from primary to secondary, but
the HDMI monitor won't come on. I can unplug the HDMI and the other
monitor becomes primary again.
How do I get both monitors working again and then how do I tell if my
Graphics card is bad?

If you plug the main monitor into the HDMI port and leave the secondary
unplugged, does the primary monitor work? If it does, then I would think
that the graphics card is OK. If the primary remains blank, well, you see
where I'm going here :-(

--
SC Tom

Seymore4Head

2018-03-28 15:14:26 UTC

Permalink

Post by SC Tom

The HDMI didn't work when I plugged it either port.
I think my next step will be to take the monitor and plug it into
another machine. I suspect it may be the monitor.

Paul

2018-03-28 19:11:10 UTC

Permalink

Post by Seymore4Head

Post by SC Tom

The HDMI didn't work when I plugged it either port.
I think my next step will be to take the monitor and plug it into
another machine. I suspect it may be the monitor.

Does the other machine have an HDMI cable on it you can use
for testing ? Other than the 25 foot one.

Paul

John

2018-03-30 02:33:34 UTC

Permalink

Post by Seymore4Head

Post by SC Tom

The HDMI didn't work when I plugged it either port.
I think my next step will be to take the monitor and plug it into
another machine. I suspect it may be the monitor.

Have you tried plugging it into the mains? And *checking* it is
plugged in?
And have you tried flicking the "on/off" switch/button on the
monitor?
Have you checked the brightness?

Yes, those are stupid questions but you'd be surprised by how many
"my computer is totally broken" calls to the help desk end with a
quiet "oh!" when they are asked.
J.

Wolf K

2018-03-28 14:08:00 UTC

Permalink

The above indicates that DVI works with both monitors (primary +
secondary). If so, that's what I'd stay with until I decided on other
solutions. I surmise "plug in the HDMI" means that the mobo has onboard
HDMI, in which case the monitor has been damaged. IMO the graphics card
is toast.

Post by Seymore4Head
How do I get both monitors working again and then how do I tell if my
Graphics card is bad?

I suspect that the dog's saliva created a nice little short in the HDMI
cable, which propagated backwards to the HDMI chips on the graphics card
and the monitor and fried something.

So if I wanted to stick with HDMI, I'd replace the graphics card (which
raises additional issues, see below), and the monitor. Or pay a tech to
test and fix the monitor, which may cost more than a new monitor.

I'd do something about the dog, too. Nothing drastic :-), just something
to keep him away from the electronics.

Footnote: Replace the graphics card or not:
Whenever a major component on a system has to be replaced, the question
that begins to niggle is, "Is it worth it, or should I buy a new(er)
system?"

New(er) machines have excellent onboard or in-chip graphics, usually as
good as or better than most graphics cards of yore (major exception:
gaming graphics). Since you're running Win7, I surmise you have an older
machine. If it's 5 years +, a new(er) machine may well be a better
option than repair or upgrade of what you have. Takes a fair amount of
searching and calculation to arrive at a clear enough choice between
repair, upgrade, or keep a while longer. May be worth it merely as a
learning experience. :-)

Best wishes,

--
Wolf K
kirkwood40.blogspot.com
"The next conference for the time travel design team will be held two
weeks ago."

pjp

2018-03-28 18:37:07 UTC

Permalink

Post by Wolf K

Post by Seymore4Head
How do I get both monitors working again and then how do I tell if my
Graphics card is bad?

I suspect that the dog's saliva created a nice little short in the HDMI
cable, which propagated backwards to the HDMI chips on the graphics card
and the monitor and fried something.
So if I wanted to stick with HDMI, I'd replace the graphics card (which
raises additional issues, see below), and the monitor. Or pay a tech to
test and fix the monitor, which may cost more than a new monitor.
I'd do something about the dog, too. Nothing drastic :-), just something
to keep him away from the electronics.
Whenever a major component on a system has to be replaced, the question
that begins to niggle is, "Is it worth it, or should I buy a new(er)
system?"
New(er) machines have excellent onboard or in-chip graphics, usually as
gaming graphics). Since you're running Win7, I surmise you have an older
machine. If it's 5 years +, a new(er) machine may well be a better
option than repair or upgrade of what you have. Takes a fair amount of
searching and calculation to arrive at a clear enough choice between
repair, upgrade, or keep a while longer. May be worth it merely as a
learning experience. :-)

The problem with getting a new pc now is that it comes with Win10 and
there's no quarantee it will even run Win7 propely as there probably
aren't Win7 drivers for it.

Paul

2018-03-28 14:53:14 UTC

Permalink

The HDMI cable has a +5V wire on it. If the +5V wire touches
the I/O pairs, it could damage either a transmitter pad
driver or a receiver pad.

You did the test with a new HDMI cable, the monitor didn't work.
That means something on the video card end is blown.

In a situation like this, you should do as much testing with
the "damaged" goods, to not endanger "new" goods quite yet.

Use the working outputs on some video source, and the
ports on the monitor, to assure yourself that the monitors
haven't been damaged in any way. You at least want to verify
the monitors, before jumping to any conclusions.

This means trying permutations and combinations using the
existing goods, to work out whether the video card has
a defective output, or the monitors have something blown.
Individual tests, one test case at a time, should suffice.
(I.e. an electrical failure should not be causing
desktop monitor order issues). Just make sure each
port works individually, as part of your damage
assessment. You can test the monitor ports, one at
a time, using the chipset/motherboard connectors.

*******

Onboard (so-called "chipset graphics), can have usage
limitations. The HDMI and DVI-D could actually be sharing
the same wire lanes, and the manufacturer "intended" the
user to only use one at a time. On a chipset DVI-I,
sometimes a manufacturer splits one of those and
makes a DVI-D connector and a VGA connector. The driver
may not support using both at once, depending on how
it views usage of the crossbar on the GPU output.

These details are not documented anywhere. The hardware
maker is "ashamed" to admit to such things. It is left
to people in forums to document "I can't run DVI and
VGA at the same time on this motherboard".

Newer gear doesn't have these limits. You can run three
monitors off the back of the motherboard.

You're going to need to datamine, using CPU/chipset/motherboard
details, to get some usage rules.

*******

Now, pop another video card in there, and move on.
Nobody really likes chipset graphics all that much, and
especially if driving multiple monitors.

One disadvantage of modern video cards, is they've lost
the VGA connector. You might find DVI, HDMI, DisplayPort,
but we appear to have passed the VGA era. In an emergency,
you can convert DisplayPort to VGA with an adapter,
so that remains as an option, but increases the
price of the "repair".

A low end card now, can be two slots wide, even though
they could have made it a bit thinner. You have both
a connector issue (not the right mix for your existing
monitors), as well as the thickness of the card perhaps
interfering with other stuff in the PC.

Good luck,
Paul

Seymore4Head

2018-03-28 15:53:48 UTC

Permalink

I wanted to test to see if the HDMI monitor was working. I have a
Firestick so I plugged that into the HDMI port and the monitor worked.

Someone suggested the onboard HDMI and the DVI can't work at the same
time. So I unplugged the DVI and plugged in the HDMI. The HDMI does
not work. The spare cable I have is a 25ft HDMI cable that was
working the last time I used it.

How can the monitor work with the Firestick and not work with the 25ft
HDMI cable?

I don't think either monitor was plugged into the mobo and both were
plugged into the Graphics card. It seems very remote that the mobo
port was effected by the chewing HDMI plug.

I still have not put my Graphics card back in the computer. What
should I try next?

Paul

2018-03-28 19:09:52 UTC

Permalink

Post by Seymore4Head

I wanted to test to see if the HDMI monitor was working. I have a
Firestick so I plugged that into the HDMI port and the monitor worked.
Someone suggested the onboard HDMI and the DVI can't work at the same
time. So I unplugged the DVI and plugged in the HDMI. The HDMI does
not work. The spare cable I have is a 25ft HDMI cable that was
working the last time I used it.
How can the monitor work with the Firestick and not work with the 25ft
HDMI cable?
I don't think either monitor was plugged into the mobo and both were
plugged into the Graphics card. It seems very remote that the mobo
port was effected by the chewing HDMI plug.
I still have not put my Graphics card back in the computer. What
should I try next?

Perhaps pick up a replacement HDMI which is the same
length as the one the dog chewed ?

It's possible the onboard chipset graphics aren't detecting
the HDMI termination resistors. Or, maybe a setting needs
to be made somewhere to change ports (it's decided not to
auto-switch on its own). On a laptop, you'd have an F-key which
you could use, to switch the graphics output from port to port
on the GPU. I doubt the binding for such is set up on a
desktop.

Maybe you could use the chipset VGA to one monitor,
then try to bring up the chipset graphics Display
panel and enable the HDMI from there ? Grasping
at straws here...

Paul

Jeff Barnett

2018-03-29 01:44:44 UTC

Permalink

We have a cat who enjoys chewing on all cables and cords. Our solution
is something called "split loom cable wrap." It is a wrapper for cords
of all sorts. You cut an appropriate length of wrap then put the cable,
wire or what not in it - the wrap can be pulled open length wise so it's
relatively easy to apply. We have used around a thousand feet of the
stuff (plus or minus a few hundred) and we use more every time a new
electric device is brought into the house. We have wrapped cords from
appliances, extension cords, all cords and cables to and from our
computers and entertainment boxes (TV etc.).

This cat is a destructive idiot and shows no signs of maturing -
youngest of five by several years. We like him so we will continue
ordering split loom. Fortunately we discovered the problem and solution
before he did too much damage. The most expensive loss was the
recharging mechanism for my electric toothbrush: $80 since the part was
no longer supplied by the manufactured.

Pet your puppy for me!

--
Jeff Barnett

Seymore4Head

2018-04-07 15:42:13 UTC

Permalink

The problem turned out to be the 25 ft HDMI cable. I have used the
cable before to connect my laptop to my 50 inch TV, but I quit using
it when I bought the WDTV player.

I tried using the HDMI cable with the WDTV player to just test it, and
I could see the opening screen but it would the picture would flash in
and out.
I bought a 10 ft cable and all is well.

I sure am glad my video card did not get fried.

Thanks everyone

Wolf K

2018-04-07 18:22:02 UTC

Permalink

On 2018-04-07 11:42, Seymore4Head wrote:
[...]

Post by Seymore4Head
The problem turned out to be the 25 ft HDMI cable. I have used the
cable before to connect my laptop to my 50 inch TV, but I quit using
it when I bought the WDTV player.
I tried using the HDMI cable with the WDTV player to just test it, and
I could see the opening screen but it would the picture would flash in
and out.
I bought a 10 ft cable and all is well.
I sure am glad my video card did not get fried.
Thanks everyone

Good to know. Thanks for reporting back. Sounds like at 25ft the
impedance was just too much for the video card to handle.

--
Wolf K
kirkwood40.blogspot.com
"The next conference for the time travel design team will be held two
weeks ago."

Paul

2018-04-07 20:54:24 UTC

Permalink

Post by Wolf K
[...]

Good to know. Thanks for reporting back. Sounds like at 25ft the
impedance was just too much for the video card to handle.

The parameter you want, is likely to be "loss" or "dielectric loss".

The AC impedance is actually constant, whether the cable is one foot
long or twenty five feet long. HDMI cable is 100 ohms
differential on R,G,B,CLK. A resistor on each of those
signal pairs in the monitor, terminates the cable in
its characteristic impedance of 100 ohms. In fact, the
video card detects it should output a signal on the
cable, by noticing a 100 ohm load on each pair.

The launch amplitude might be on the order of 1V,
just making up a value.

The "loss" in the cable, might cause the amplitude at
25 feet, to be only 25mV. And that's sort of the
sensitivity limit at the receiver. The signal
is too weak then, to be cleanly thresholded
and turned into ones and zeros. Either the
picture has colored snow (if slightly degraded),
or eventually the synchronization information
is lost, and the monitor switches to a black screen.

Now, the really funny part, is HDMI cables come in
different material compositions. They might have to
meet some minimum level of performance. But in
some cases, the dielectric loss of one cable
might be significantly better than another cable.
If you bought ten 25 foot cables and compared, maybe
one or two of them actually worked at that distance.

And we're not talking Monster cables here either.
Spritzing 10u of gold plating on the connectors
on either end, doesn't convert a cable into a "hero".
But a change of "plastic" dielectric in the cable,
could make a difference (polystyrene or teflon).
Some of the dimensions of things inside the cable
might have to change, if the dielectric is modified,
so such a change is not without some visible side
effects. Cutting samples of good and bad cables,
and looking at a cross-section, might reveal differences.

By comparison, as far as I know, all SATA cables are
made the same way. But things like HDMI, who knows
what they stuffed in there.

All that the cable has to do, is present the signals
with enough amplitude and good enough group delay
that the digital signal can be recovered. If the
cable is made "even better", there's no difference
in the picture or sound. Once all bits are received
error free, getting 100mV of amplitude instead of
50mV, doesn't "make the picture brighter or the
sound sparkle". This is digital transmission, not
analog, so the degradation tends to be "make or break",
rather than "fuzzy or soft".

https://www.cnet.com/news/why-all-hdmi-cables-are-the-same/

Some actual tests.

https://web.archive.org/web/20110525140343/https://hdguru.com/all-hdmi-cables-are-the-same-or-are-they-full-test/4373/

*******

The VGA era was different, in that as the cable length
went up, we would adjust the resolution down to compensate.
At zero feet, maybe the setup supported 1600x1200, while at
100 feet, a setting of 1024x768 is usable, and 1600 would
be out of the question (too fuzzy). The degradation was
a kind of "continuous variable" with VGA. Not the abrupt
"make or break" of HDMI.

It's possible for some effects like that with HDMI, but
the user isn't always at liberty to switch down to 640x480
in order to make a long cable work. Maybe an output device,
only outputs HD 1920x1080 (say, a DVD player).

*******

There may be various proposals to make "smart cables", and
have the destination end send a signal back to the driving
end, to adjust the line build-out. But thinking along these
lines works best, if the idea is standardized so all equipment
supports the idea.

https://patents.google.com/patent/US9042437

For a price, you can probably send an HDMI signal with a
fiber optic cable. And then the reach might be kilometers.
But the simple wire cable is cheaper.

You can also send HDMI wirelessly, at 60GHz. As long as
the transmitter and receiver are in the same room, in
line of sight, and preferably less than 25 feet apart.
The fiber optic transmitter might be cheaper :-)

Paul