Tv won't display computer output (when it did previously)

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dramatic

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Topic # 220390 8-Aug-2017 23:12

Today's task: Replace old WinXP kiosk computer with the Win7 box i've been setting up. Display is a panasonic viera tv, maybe 42", which counts as a non-PNP monitor.
All is going well until i try and correct aspect ratio by changing the resolution (i've already changed it twice) to 1440*900, and I stupidly click ok tather than preview. Display throws a wobbly and just goes to black screen with PC mode indicator. I hook new PC up to monitor I've been using during setup and reset resolution lower. (Check, video card not stuffed). Still no display on big screen.
Next i hook up old computer. Big screen still works fine with that.
So what can I do to make the display talk to the new computer again? Connection is SVGA.

Brumfondl

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Reply # 1841499 8-Aug-2017 23:15

Are you sure the TV can actually handle 1140x900?

sbiddle

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Reply # 1841536 9-Aug-2017 07:15

Why are you trying to force that resolution? I would highly doubt that you'll find any TV out there that can support that resolution. Have you looked to see what resolutions the TV does support? If the TV is a similar age to the XP machine and it's something like an old 42" Viera Plasma you'll find it only supports 1024x768 maximum despite being a 16:9 panel.

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richms

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Reply # 1841547 9-Aug-2017 07:36

Try another cable if its showing as a non pnp monitor, sounds like the edid pins are not connected and its falling back to that instead of reading what the monitor supports correctly.

See it a lot with people who have swapped monitors and PCs many times, but kept the same early 90's VGA cable in place because they are lazy. Even on a place with new PCs and monitors with displayport, and displayport cables in the box but using VGA because that is what went thru the hole in the desk.

Richard rich.ms

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Reply # 1841846 9-Aug-2017 13:41

It may be a refresh rate issue . Seems unlikely, but worth checking.
Also, res too low can sometimes cause issues : rare but happens .

Use HDMI or DVI instead of vga , it may then autodetect the correct settings .

Oblivian

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Reply # 1841873 9-Aug-2017 14:27

sbiddle:

Why are you trying to force that resolution? I would highly doubt that you'll find any TV out there that can support that resolution. Have you looked to see what resolutions the TV does support? If the TV is a similar age to the XP machine and it's something like an old 42" Viera Plasma you'll find it only supports 1024x768 maximum despite being a 16:9 panel.

Could even be an odd one like 1366x768. More so if it is a VGA 'PC' input only. (the specs usually define this clearly in manual) HDMI/DVI-HDMI tend to be the only ones able to process the image at true 1080i resolutions. Cause well, analogue.

F8 on PC bootup into safe mode and adjust it back to a dumb resolution (itll be in 800x600 by default). And watch if AMD drivers. They recently started doing funny things like forcing 24Hz to mine which end in out of range errors.

dramatic

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Reply # 1845144 11-Aug-2017 13:08

Addressing everyone's points:

The Plasma TV arrived a few weeks ago, donated by a hotel. It's not new, but in pristine condition - I'd estimate 1-3 years old. Unfortunately the mounting bracket is covering the model ID. From Panasonic manuals I've found online it looks as though it will be WXGA - 1366x768

The TV supports HDMI of course, but the PC doesn't (It's an ex-lease HP Elite 8300 - an office-spec box).

Changing the VGA cable made no difference.

I'm seeing the windows boot sequence (at 1024 x 768) until the user settings kick in.

Using Regedit from Safe Mode, under HCCC\System\ControlSet\Control\VIDEO i have about 4 branches with typical hex-string names. a couple have XResolution and YResolution values of 1440 x 900, and changing them to 800x600 doesn't fix things. Frequencies all seem to be 60Hz

Apparently the default resolution of the monitor I used for setup is 1440x900, so I may have to resize some web page elements once I get the display working :-)

Oblivian

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Reply # 1845157 11-Aug-2017 13:25

While in safemode, remove the video driver and reboot.

It will start with MS VGA and then install it and do a EDID detection.

If its the model I'm thinking of, they have digital display port. You can go DP-HDMI with ease, then it could do a better resolution.

dramatic

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Reply # 1847544 16-Aug-2017 13:08

Just got back to this: Uninstalled Display driver (which is Intel HR), rebooted and got working VGA - with, of course, no widescreen modes.

Windows reinstalled driver automatically, asked for reboot, which I did, and... broken again.

Which probably means that uninstalling the driver isn't properly cleaning the settings from Registry.

I'm about to try a rinse and repeat, but changing the resolution in the VGA driver, to see if that overwrites anything. If not, how can I clean out the unwanted settings?

Oblivian

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Reply # 1847558 16-Aug-2017 13:18

http://www.majorgeeks.com/files/details/display_driver_uninstaller.html

Throw on a (vga) monitor. Lower resolution to below 1366x768. Plug in VGA.

But it should be scaling based on info fed back. Or set a custom resolution/refresh rate.

But seriously, look for a display port outlet. Pretty sure from the 8200 model up come with. Which is digital and will solve the issue with HDMI resolutions.

dramatic

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Reply # 1847573 16-Aug-2017 13:35

Just to complicate things, this time Windows decided not to reinstall the drivers for the Intel Graphics - and scanning for hardware changes isn't finding it. Downloaded what I thought was the correct driver from Intel, but it said computer doesn't match.

Oblivian

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Reply # 1847581 16-Aug-2017 13:48

Likely candidate for the range

https://support.hp.com/gb-en/drivers/selfservice/swdetails/hp-compaq-8200-elite-small-form-factor-pc/5037931/swItemId/vc-140586-1

dramatic

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Reply # 1851220 23-Aug-2017 12:52

HDMI to the rescue :-) Although the natural resolution at 1080p is lower than the natural resolution stated for SVGA, 1366 x 768 is working. Once I figured out how to disable overscanning.