Re: Problem with Dell 1703FP monitor - SOLVED

From: MooNPuP (slackerama_at_no.yahoo.com)
Date: 11/14/04 

Date: Sun, 14 Nov 2004 10:48:15 -0500

David Wright wrote:
> MooNPuP wrote:
>
>
>>Hi All,
>>
>>I'm running SUSE 9.2 and am just short of being completely happy with
>>it. My problem is that I have selected the correct monitor Dell 1703FP
>>and verified it had the correct horizontal and vertical sync ranges etc.
>>
>>I am running it at its max resolution 1280x1024 with 24 bit color. I've
>>tried lower resolutions but the screen and icons are just too big.
>>
>>Anyway, the problem I have is the dreaded screen flicker when you look
>>at the corner of a window or the scroll bar, icons etc. It's really
>>annoying and is marring my almost perfect desktop.
>>
>>I thought it might be electrical interference, so I tried plugging into
>>a different outlet etc, no change. Also, it is plugged into an APC
>>battery backup so I would assume the electrical noise to be minimal.
>>
>>The only other thing is that I have the monitor hooked up to an Iogear
>>KVM switch that also connects my linux server. Maybe the KVM could be
>>causing interference. But when I'm switched over to the linux server
>>running console only (no X), the display is fine.
>>
>>Anyway, ideas or fixes appreciated.
>>
>>Cheers!
>
>
> Two things I can think of off hand to start with.
>
> 1. What refresh rate is the monitor running at in 1280x1024 mode? You should
> be looking for at least 75Hz, 90+ would be better and 100+ should be rock
> steady, even out of the corner of the eye.
>
> A lot of monitors cannot manage a high refresh rate at their maximum
> resolutions, maybe at 1280x1024, it can only manage 60-70Hz or something.
> Or maybe YaST/Sax2 is defaulting to the minimum available scan rate. You
> haven't posted what the actual refresh rate is according to YaST...
>
> 2. If it is electrical interference, then there are a few things to try:
>
> a. Unplug the monitor from the KVM temporarily and plug it directly into
> your PC, this will discount the KVM causing problems (and remember, going
> through a KVM with an analogue signal will always degrade its performance,
> depending on the quality of the KVM this may or may not be noticeable...
>
> b. Check for other electrical devices in the area and turn them off for
> testing (obviously a bit hard if you are running a server for other people
> as well as yourself), also check how far the PC and its cables are away
> from the cables running in the wall/conduits. I had a similar problem in an
> old office several years ago. It turned out that the light cabling was
> running up a conduit behind my desk to the fluorescent lights, and it was
> causing a lot of interference. Moving the monitor a bit and putting some
> shielding over the conduit solved the problem.
>
> 3. Is the monitor really up to 1280x1024? If this is the monitors maximum
> resolution and the monitor is getting old it may start showing defects when
> running at such a resolution. See if you can borrow another monitor and try
> that.
>
> I had problems with a TFT panel here. The monitor started flickering
> occassionally (not a low display rate flicker, but a flicker as in it would
> drop some frames and drop one of the colour signals (whites would become
> pinks or pale blues for example). Tapping the monitor would get it to
> behave for a while. It was connected via the VGA port. Then I upgraded the
> video card in the machine that is connected to it, and the new card had a
> DVI port, so I switched to a digital signal and it is back to rock steady
> and doesn't keep dropping one of the colours. My conclusion (after running
> it on analogue for a while with the new card (and several different
> cables)) is that the analogue receiver in the monitor was breaking down.
>
> Hope that helps a bit with the troubleshooting.
>
> Dave
Hi David,

Thanks for the well thought out answer. As you suspected it was the
Iogear KVM switch. I disconnected it and plugged directly into the
computer, no more flickering.

Now I may be forced to buy a new KVM switch...hmmm

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