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10-12-2016, 10:00
EDIT 14/12/2016: The title of the thread no longer matches the problem I am asking help for. It should be changed for accuracy (but I don't know how it's done :p). Go to post #4 for the update.

Hello. I'm trying to get a 15 kHz output but I haven't been able to do it. [Noob alert :p]

This is what I do: I download soft15khz and quickres; I run soft15khz and enable 15 kHz for my card. Then I switch to 640x480 resolution (or not) with quickres. These programs are always run with admin privileges. Then I reboot.

I have done it with two computers (both graphics cards are implemented):

* Intel HD Graphics 4000, Windows 8.1 x64

* NVIDIA GeForce 6150SE nForce 430, Windows Vista Home Premium x86

After the reboot, everything is the same: the resolution choosed with quickres is kept, and I see it through the VGA signal. So the 15 kHz mode is not working (if connected to TV, nothing can be seen).

Does this automatically mean none of these graphics cards won't work for a 15 kHz output?


12-12-2016, 07:09
SailorSat has to jump in here.

Are you sure your TV is ready to show the 15kHz signal? Is RGB enabled on the Scart-input?

12-12-2016, 08:50
Yes, sorry. The cable I bought wouldn't enable it, but it's already fixed. I recorded a demonstration video:


In addition, I suspect my cable misses the vertical and horizontal syncronisation signals, but since I haven't been successful in having the graphics card output 15kHz video, I haven't thought of making any more changes to the cable.


13-12-2016, 22:54

You can forget all the specs I provided before. After learning more about this, I have moved to Windows XP and decided to use a NVidia GeForce 7950 GT that somebody gave me time ago (I didn't do this from the beginning because I hadn't realised my other cards were not likely to be compatible with 15 kHz output).

Now there is another problem. Default 15 kHz modes provided by Soft15kHz and WinModeline don't look any good on the CRT TV I'm using; so I have been tweaking output frequencies with PowerStrip.

The fartest I could get was realising the following things, for a resolution of 720x540 interlaced:

* Any minor change in horizontal frequency will easily cause the picture heigh to become very little, so that it will appear many times on screen, and it's not possible to distinguish any detail.
There are a very few values around 15,356 kHz which will provide a picture with almost full vertical resolution. Moving to values under 15,320 and above 15,380 approx. will cause the picture's vertical sides to incline (like a rhombus) until the situation I described in first place can be seen.
Actually, the precision of PowerStrip when tweaking the frequency in real time is not high enough to meet the perfect value for a perfectly vertical picture. I'm not saying it's PowerStrip's fault, of course.

* Picture would shift (move) vertically all the time for a vertical frequency of 25 Hz. Only when getting near to 21 Hz the vertical shift becomes stable.

* I couldn't find a way to stop the horizontal shift (movement). I could not learn that much from just tweaking without knowing very well what's happening.

Please take a look at the footage:


Given the unreasonableness of having the picture all screwed up just because of a few Hertz, I suspect it's my adapter's fault for not having the syncronisation signal. But I don't know very well what the consequences of this are, so that's what I wanted to ask you. How does the TV use the syncronisation signal? Do you think it would get automatically better by changing to a VGA-SCART adapter with the recommended (http://www.geocities.ws/podernixie/htpc/cables-en.html#vgascart) connections for it?


14-12-2016, 10:02
perhabs you need an EDID Dongle, but i am not 100% sure


Sailorsat mentioned the 8 and 9 Series Gforce Cards.. This is why i use only ATI Cards.. ;)