Dual Head hardware problem

[Jkun]

I have a G400 32MB dual head with a CTX 19" CRT monitor and a Philips 181AS analog LCD monitor.

Analog LCD monitors accept analog VGA and digitize it to display on LCD. This means they need a clean lock on the signal. My Philips is very good at this - one click on the autoadjust button and the image is sharp and clear.

Except when I enable dual head mode. Then there is a regular pattern on the Philips where the image is not sharp.

It looks as if the clock signal of the G400 is distorted or overlaid with a sine wave.

What exactly do I see: on a screen filled with black text on white background I will see vertical columns where the text is unsharp, about 1/6th of the screen wide. In between are columns where the picture is sharp. The regularity of this distortion indicates something like a sine overlaid on the G400's clock.

Any tips on how to remedy this would be welcome but I fear this is a hardware problem of the G400 dual head.

Who do I best contact at Matrox with this? Techsupport at UK won't reply.

I am mainly concerned about getting a G450 - if it has the same problems, it is no good to me. I can't borrow cards from the stores I buy from, so I need to know beforehand.

If there's a hardware fix for the G400 that would of course be even better...

J-kun

[This message has been edited by Jkun (edited 15 September 2000).]

[SteveC]

You sure there's nothing nearby which could be causing interference? Try putting the LCD screen on the primary head and turn off your other monitor. Also, what about flourescent lighting? If you have that, try turning it off.

I have seen this before, and I think I got rid of it by altering the refresh rate from 75 Hz to 85Hz.

------------------
Cheers,
Steve

"Life is what we make of it, yet most of us just fake"

[Jkun]

Nope, no interferences.

I run the 181AS at 60 HZ(best refresh rate for LCD), 1280x1024 native res. on the primary head. I leave the CTX unconnected.

Running the G400 in single head mode: perfect picture.

Switching to dual head mode (all refresh rates tried) : immediately crappy picture.

Definitely a hw issue of the G400 dual head feature (I tried a second G400, same result). I suspect they use the same quartz to drive the 2 heads, and the division is causing this.

J-kun

[Haig]

Are you seeing one strip dark, next strip light, next strip dark, next strip light etc all across the screen?

Haig

[Jkun]

Nope, one strip sharp letters, one strip fuzzy letters etc etc.

The signal isn't as cleanly locked in the fuzzy parts. Only happens when dual mode is enabled.

Seems there are beta drivers that may fix this, will try them and report back.

Hope this doesn't mean my video tools v1.52 will no longer work - need those for YUV.

J-kun
J-kun

[Chucky Cheese]

jkun,

i have a similar configuration and i don't have this problem. i am running the 5.03.?? certified drivers. all my fonts and icons are clear and sharp on the FPD. is there any way for you to check and see if your philips display is set for "interlacing"??

i have a 21" panasonic on the primary and an analog(..or optional digital) 17" FPD(..samsung 770 tft) on the second head. my "defined" resolution in device manager for the "monitor" is 1280x1024 at 16 bits 75 hz. my actual desktop resolution is 2560x1024 at 16 bits.

cc

[Jkun]

Thanks for replying.

No, there's no menu item for 'interlaced'

But since it works fine for single head, I don't think this is the problem. Haven't had time to test the new beta drivers yet :-(, once I do I'll post an update.

J-kun

[Wombat]

Are you sure that both monitor cables are properly shielded?

[Jkun]

Yes, cables are OK. I tried switching cables, using BNC cables etc.

No go. It's definitely something with the G400 dual head feature.

On the official Matrox support forums, I received the reply this sounded like a known issue with analog LCD monitors, and I should try new beta drivers. I dl'ed them but sofar lacked time to get them up and running so I could test it

J-kun