Monitor not being properly recognized by 25 ft. vga cable

  • Thread starter Thread starter Mike
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M

Mike

Hi all,

VERY weird problem I am having here. I bought a 25 ft. vga cable to
run from my shuttle to my 19" widescreen flat panel. The native
resolution for that puppy is 1440 x 900. It runs fine on the default
VGA cable that came with the monitor, but when I hook up the longer
cable it won't even let me select 1440 x 900, and just lists a bunch of
unsupported resolutions.

My thinking is the cable is having a problem rpoperly recognizing the
monitor, but I didn't even know cables did this to be quite honest. Am
I going to return this one and get another instead, or is there some
way of forcing the cable to recognize the monitor? FYI I have tried
looking for drivers for the flat panel, but Proview doesn't make any,
and any I do find, don't seem to install... but the monitor works fine
on the smaller cable with the default monitor setting anyways so I
don't see how that could be the problem.

Any help would be mucho appreciated :)

Cheers
Mike
 
Mike said:
Hi all,

VERY weird problem I am having here. I bought a 25 ft. vga cable to
run from my shuttle to my 19" widescreen flat panel. The native
resolution for that puppy is 1440 x 900. It runs fine on the default
VGA cable that came with the monitor, but when I hook up the longer
cable it won't even let me select 1440 x 900, and just lists a bunch of
unsupported resolutions.

My thinking is the cable is having a problem rpoperly recognizing the
monitor, but I didn't even know cables did this to be quite honest. Am
I going to return this one and get another instead, or is there some
way of forcing the cable to recognize the monitor? FYI I have tried
looking for drivers for the flat panel, but Proview doesn't make any,
and any I do find, don't seem to install... but the monitor works fine
on the smaller cable with the default monitor setting anyways so I
don't see how that could be the problem.

Any help would be mucho appreciated :)

Cheers
Mike
Click to expand...
The cable is either incorrectly wired or is too low quality to work at
that length. How much did you pay for the cable? For a 25' cable to work, it
needs to be very high quality with lots of screening for each conductor. you
could try 2 of these:--
http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=1831

Mike.
 
The practical fact of the matter is that the recommended LIMIT for VGA cable
length is 10 feet (3 M). Beyond that the signal attenuation is too great to
obtain a useable image.
 
Hi Mike!
I used to have a Shuttle actually, that was connected to the monitor
with a VERY long cable - 30 metres (98.5 feet according to converter.
(I posted about this previously in this group and got some very helpful
advice. )

The cable was very high quality from, a company called Lindy. The
connectors were gold plated and the cable was insulated.
I was using an nVida medium spec graphics card in the Shuttle (e.g. I
was not using the native motherboard card).
The monitor in in question is an Acer 20" widescreen.

With this cable I DID get the SAME resolutions/frequences as with a
normal length cable.
Everything was the same except for one thing: The imagine was sort of
'floating' a bit - just shaking a tiny bit. This was down to reduction
or disturbance to the signal. It was really no major problem - Not more
irritating than viewing a CRT in 60Hz resolution.

However I found it unbearable anyway.... and ordered a 15 metre cable
from the same company!
(I had miscalulated the length I needed, so 15 metres did the job. This
is 49.2 feet. )

The whole thing was a terrible waste of money. I still have the 30m
cable which cost me £80..... Cannot in good conscience sell it.
Somebody in this group told me I was pretty daft for buying it in the
first place.. can't argue with that.. ;-)

You may want to look into whether there are signal boosters available. .

If you are certain that you need a cable this long, you should probably
make sure that all the components are high-end, e.g. graphics card... (I
imagine...?) but mainly the cable. I am not particularly good with this
stuff, just sharing my experience...

However I can verify that the 'max 3 metres' rule does not apply if you
are using a high end cable.
The 15 metre cable (49.2 feet) from Lindy works flawlessly with my Acer
monitor and nVidia graphics card.

Good luck with this
Jo
 
Thanks to everyone for the helpful responses, normally I would say it
was spot on that the item was cheap, however there is one small factor
the leads me to believe it's not a cheapness factor.

Here's the scenario, boot the computer up with the short cable, choose
the 1440 x 900 setting, resolution is crisp and clear and, well,
perfect... remove the cable, with the computer still on, and plug in
the 25 footer, oddly enough the signal is STILL crisp and strong, as
good as the short cable. So the cable CAN do this resolution, or so
this would lead me to believe. Now... reboot the computer, with the 25
footer attached, and voila, 1440 x 900 resolution is GONE, won't let me
select, doesn't even display it in the all modes available list box.

So I'm thinking the cable DOES work fine, and CAN carry the signal
properly... BUT... it won't... which leads me to believe a mis-wiring
may be the cause as you suggested, in that whatever pin the monitor
uses to tell the card its details, it's not doing its job, and only
works when I "force" the resolution using the other cable first.

With that in mind, does anyone else have any ideas? Or is this a lost
cause.

Cheers
Mike
 
"Mike" said:
Thanks to everyone for the helpful responses, normally I would say it
was spot on that the item was cheap, however there is one small factor
the leads me to believe it's not a cheapness factor.

Here's the scenario, boot the computer up with the short cable, choose
the 1440 x 900 setting, resolution is crisp and clear and, well,
perfect... remove the cable, with the computer still on, and plug in
the 25 footer, oddly enough the signal is STILL crisp and strong, as
good as the short cable. So the cable CAN do this resolution, or so
this would lead me to believe. Now... reboot the computer, with the 25
footer attached, and voila, 1440 x 900 resolution is GONE, won't let me
select, doesn't even display it in the all modes available list box.

So I'm thinking the cable DOES work fine, and CAN carry the signal
properly... BUT... it won't... which leads me to believe a mis-wiring
may be the cause as you suggested, in that whatever pin the monitor
uses to tell the card its details, it's not doing its job, and only
works when I "force" the resolution using the other cable first.

With that in mind, does anyone else have any ideas? Or is this a lost
cause.

Cheers
Mike
Click to expand...

Cables come in versions that have the full complement of VGA signals
in them, and there are also cables intended for home theatre applications.
If the serial DDC signals are missing, there is no way for the
monitor to pass its max resolution settings to the computer.
The computer operating system assumes some safe default
values (i.e. less than 1440x900), if the computer boots and
cannot get the DDC signals.

It may be possible to force the video card to the desired
resolution, so that could be one solution.

Booting with the short cable, allows the EDID info (carried
on DDC) to be extracted during boot. The resolution choices
could remain in place once the longer cable is fitted after
booting.

Theoretically speaking, you could add some ordinary wires in parallel
with the long cable, and connect them to the appropriate pins
where the wires are missing, on either end of the cable. But gaining
access to the connectors would either be impossible or make a mess
of the nice new cable.

SDA and SCL are the serial data and serial clock signals used
for passing EDID:

http://en.wikipedia.org/wiki/VGA_connector
http://en.wikipedia.org/wiki/Extended_display_identification_data

Paul
 
Did you try with a DVI cable..? Or even with another VGA cable the same
length?
The key to fixing any IT problem (as you probably know) is to isolate
the problem until you can trigger it at will. Right now I think you
don't know for certain whether the problem is with the cable or, for
example, or with the monitor or the graphics card.

(I experienced some differences between what resolution I was getting
depending on whether I used DVI or VGA. However I was super busy with
work at the time and did not look into the reason for this. I simply
decided to use VGA instead of DVI as I actually thought the VGA gave a
better picture quality. )

Sometimes in IT - both hardware and software - you get to a brick wall,
where something illogical or completely incomprehensible is going on.
You do your best to find out why, but you can't...
The situation is irritating, because you know that there WILL be a
logical solution (since computers are logical).

In such situations, the best thing to do is normally to find a
workaround, instead of continuing to try to get to the bottom of the
problem. In the process of troubleshooting you will have learnt enough
to be able to do a workaround. In software development, this happens a
lot. Sometimes you just have to cut your losses and get on with it.

Vendor tech support is usually a complete waste of time unless you
manage to get through the layer of people between you as a customer and
the 2nd/2rd line support (or even product developers).

If you still have the reciept for the cable, take it back and say
confidently that you believe there is a hardware malfunction and that
you want to have a replacement (or refund). They will either give you
this without quibble... alternatively they will try to test the cable
for the problem that you describe.
If they attempt to reproduce your scenario but aren't able to
reproduce, then you have an interesting situation! That will tell you
that the problem is either with your specific home system configuration,
or a hardware fault with your home system. There are odd instances where
specific hardware components just 'don't like' eachother and don't work
together... For example, a card that works fine in one machine, but
appears dead in another.

Let us know what you decide to do!
Jo
 
Thanks again for some good suggestion as to where to look into. I
think the idea that the properties of the monitor weren't being sent
seems to make the most sense. So in an effort to essentially "force"
the resolution and basically bypass whatever the cable was saying was
appropriate I downloaded Powerstrip and used the custom resolutions
area to set a proper refresh and resolution rate for the monitor. That
works, the only drawback is when the computer reboots it obviously
resets so that the login prompt will always be blurry, but I have set
up the app to auto apply this resolution setting as soon as a user logs
in, and since I don't reboot THAT often, it's a small price to pay for
the 25 foot extension in my opinion.

I guess this is one workaround. I didn't bother going the DVI cable
route because for the amount of money for the length of cable I need it
would get into the hundreds of dollars (or 50's of pounds:)

Thanks again to everyone in the group, all your suggestions were
greatly helpful in letting me understand the basic principles behind
the complex problems.

Thanks all!
Mike
 
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