Display problem with my setup - HD3850 to sony TV via direct Component cable

[minmao]

I am really new to this, although I did spend many hours reading and search the forum and internet before posting. I really had a hard time to follow the technical details of CRT displays being discussed. 
I am using HD3850 with component output, windows xp 32 bit, the hacked driver, and connect PC directly to my TV using component cables. My TV is KV-27FS100L.
I tried default setting for groovymame, and VMMaker, as well as some suggested settings in other people's post for similar sony TVs, such as these posts:
http://forum.arcadecontrols.com/index.php/topic,131854.msg1353387.html#msg1353387
http://forum.arcadecontrols.com/index.php/topic,137379.msg1417005.html#msg1417005
http://forum.arcadecontrols.com/index.php/topic,132531.0.html
However, no matter what I tried, there seems to be two problems I could not get rid of:
1. Vertical games - Most of them, such as 1942, the picture is not centered (all the way to the left side of screen), also the displayed pictured is horizontally squeezed (so I got a very slim vertical picture on the left side of my TV), which is barely playable. Some games, like 1941, under certain settings I tried will display properly centered with reasonable horizontal width, but with other settings I tried it will behave like 1942.

2. Most of horizontal games will leave black bards on all 4 sides of the screen.  Actually when I ran ArcadeOSD, most resolutions in it  will leave black bars on 4 sides, except that 720*480 and 800*600 will go full screen (did not try higher resolution) and 640*480 will have vertical black bars on two sides.  Only a  few games seem to display in full screen if I played with settings (i.e. copy values from the posts I listed above), one I found is Three Wonders, but it seems it got some cropping on both sides horizontally (which I don't care).

Any help or suggestion to  get the vertical game right or removing the black bards will be greatly appreciated. 

[Calamity]

Hi minmao,

Please post a picture of the problem (1942) and your current settings (mame.ini).

Usually horizontal geometry is fixable by a combination of proper crt_range settings and service menu adjustments. Have you tried fixing the geometry of any mode through ArcadeOSD. You can later port the values to a crt_range in order to achieve the same geometry in GM.

Vertical width as you probably know is only fixable to some extent through service menu.

It is a bit odd anyway since the problem with TVs is usually overscan rather than underscan.

[minmao]

Hi Calamity,
Thanks for your response.
I think somehow I fixed my problem by trying to change values in Mame.ini. From one of your post to someone else's  problem with ATI card on a not even related problem, I saw you suggested to modify the value of dotclock_min.
I tried a few different values, but I realize if I set the dotclock_min below 8,  I have issues with many vertical games like 1942 as I described above. But if I have it at a larger value like 10, it will solve the vertical game problems and certain values also remove the blackbar on horizontal games. If I go too large, I will get a cropped picture.
I am not sure what this does, but it seems it will change the horizontal resolution that mame outputs (I could see a dos pop up windows showing some resolution mapping and different dotclock_min values seem to generate different resolutions). Although this corrects my vertical game aspect ratio and horizontal full screen problem, I am wondering if I am still getting the original arcade resolution which is major reason I am trying to use groovymame?

[Calamity]

Yes, I didn't notice your card is an HD 3xxx. Those need dotclock_min 8.0 or above. So the issues you were seeing were side effects of your card not applying the requested dotclocks. Basically this option duplicates the horizontal resolution when required to meet the minimum dotclock. Don't worry about this, you're still seeing the games in their native resolution because horizontal integer scaling produces the exact same video signal. Actually I recommend dotclock_min 8.0 even when it's not strictly required because it improves horizontal centering.