DOSBox 0.72 fullscreen - Invalid Scan Freq. error \ VOGONS

DOSBox 0.72 fullscreen - Invalid Scan Freq. error

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First post, by Chandro

Posted on 2008-11-30, 17:17

Chandro Offline

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Joined: 2004-10-14, 15:10

Hi all it's been a while since I've been here last but I have a maddening problem and could use some expert help.

I've just got myself a new quad-core system with Radeon 4850 graphics and 4G of memory running Vista 64 Ultimate. Very nice. Of course one of the first things I did was to install the latest DOSBox and transfer my oldgames folder from my old computer. I quickly tested it all and it all seemed to work fine, tested it in window mode that is.

So getting everything up and running I tried running a few games in fullscreen mode and kept getting the aforementioned Invalid Scan Freq. error. I eventually tried just opening DOSBox and alt-entering to fullscreen only to get the same error. Basically the monitor switches off and and the screen corrupts and a blue bar in the middle of screen bears the message: INVALID SCAN FREQ. It's like the power save message that old monitors display when you turn off the computer but leave the monitor on.

Well I tried different monitor resolution and refresh rates but nothing seemed to help. I'm now at my wits end trying to think of what the problem might be that's stopping me getting my fix of Ultima Underworld and Darklands.

If anyone could help I'd be most obliged. Thanks.

BTW I'm using the same monitor as I used with my old computer which ran DOSBox flawlessly.

Reply 1 of 6, by lightmaster

Posted on 2008-11-30, 19:11

lightmaster Offline

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monitor drivers? video drivers?

Reply 2 of 6, by Chandro

Posted on 2008-11-30, 19:25

Chandro Offline

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Video drivers are up to date, the latest Catalysts.

Monitor drivers are difficult to attain. I have an old Siemens MC212V and haven't been able to find Vista 64 drivers for it. I'm still looking though.

I did think Monitor drivers just after I posted this thread.

Reply 3 of 6, by Chandro

Posted on 2008-11-30, 19:51

Chandro Offline

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Incidently I tried it with the other Dell CRT I have lying around and I got the same monitor shut down with a different error message:

26 K / 59 HZ
Frequency out of range

I'm using an adapter to connect my CRT to my Radeon 4850 if that makes any difference. Digital to analogue I think it is.

Reply 4 of 6, by eL_PuSHeR

Posted on 2008-11-30, 20:27

eL_PuSHeR Offline

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If you are running any flavour of Windows(tm) Operating System, make sure you are using the Plug & Play monitor driver.

If your monitor is too old for this support, try looking in the manual for supported frequencies and set them accordingly in Catalyst driver (even if you need to make some custom modes or force refresh).

If your Ati videocard has two video outputs (like mine), make sure you are connecting the monitor to the primary one.

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Reply 5 of 6, by Chandro

Posted on 2008-11-30, 20:47

Chandro Offline

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Joined: 2004-10-14, 15:10

Yes, it is using Plug & Play but I've noticed something else.

Like yours my card has two video outputs and I have the other one connected to my HDTV. My computer has a blu-ray player so I watch them on the TV.

Anyway when I switch to the other monitor (the HDTV) and try to run DOSBox fullscreen, it works perfectly. So clearly the problem is with the monitor. Either the driver or perhaps the analogue to digital converter.

The monitor works fine for all the latest games BTW, Fallout 3, Far Cry 2 etc, this is the only application where I've encountered the problem. I actually though maybe DOSBox's default resolution was too low for my video card until I tested it on my HDTV.

Reply 6 of 6, by Chandro

Posted on 2008-11-30, 20:58

Chandro Offline

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Rank: Newbie
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Joined: 2004-10-14, 15:10

Ah success! At least I hope so.

I followed your advice about making sure I was connecting my monitor to the primary video card output eL_PuSHeR and since I wasn't sure which one that was I swapped them over and guess what?

It worked. DOSBox runs in fullscreen with no error message.

Thanks a lot for your help. I would never have thought of it.

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