Siemens TV picture geometry

[stiegi]

Hello everybody!

Last time I tested different crt range values in groovymame in order to fit games into the screen as good as possible. Especially Galaga with its

resolution of 288x224 was really hard to figure out because groovy mame would always select the wrong resolution and therfore leaving black

borders. I managed that the game fits the screen very well but I noticed that the screen geometry is not correct at the top of the picture.

All in all the geometry is not bad but at the top of the picture the "score" is squeezed and instead of filling the whole picture it leaves some black

lines at the top.

I messed around with arcade osd but could not get rid of this problem. I also noticed that other resolutions in arcade osd have got the same

issue namely at the top and the bottom of the geometry pattern the suares get compressed.

Does anyone know why this is happening? What are the best settings for a normal crt consumer tv in vmmaker and groovymame

(crt range) in order to get rid of this

compression and achieve a "perfect" squared pattern which fills the whole screen?


Regards,
Alex

[Calamity]

Last time I tested different crt range values in groovymame in order to fit games into the screen as good as possible. Especially Galaga with its resolution of 288x224 was really hard to figure out because groovy mame would always select the wrong resolution and therfore leaving black borders. I managed that the game fits the screen very well but I noticed that the screen geometry is not correct at the top of the picture.

I don't believe GM was selecting the wrong resolution, honestly, unless you had an very ill-formed mode list. Black borders are not a consequence of GM picking a certain resolution. If you mean 240p was being picked instead of 224p, well trust me when I say both are the same resolution from the monitor's point of view, picking 224p would produce the same borders.

Does anyone know why this is happening? What are the best settings for a normal crt consumer tv in vmmaker and groovymame (crt range) in order to get rid of this compression and achieve a "perfect" squared pattern which fills the whole screen?

You can't expect a consumer grade CRT TV to show a perfect grid pattern, side compression is actually a feature of these things. You can't fix this issue with modelines. Maybe you can manage to achieve symmetrical side compression at the most, using some controls on the chassis.

[stiegi]

Thx Calamity 

I am going to test some other tvs as well and will post my test results

regards,

[Paradroid]

You can't expect a consumer grade CRT TV to show a perfect grid pattern, side compression is actually a feature of these things.

In my experience, you can't expect every consumer grade TV to have perfect geometry but that certainly doesn't mean that no TV is capable of it.

The problem with CRT image quality is that there are so many variables and it's hard to find a single display with all the desirable characteristics in the one unit. In reality, what happens is that you find a CRT with awesome focus but crappy geometry or a unit with amazing symmetry but a wobbly picture. Next thing you know you have a room full of TVs that are "almost perfect except for...". Some things can be adjusted or repaired and others traits are inherent to the particular design.

There are definitely TVs with better horizontal linearity than your Siemens. I have some 20" Sharp and Sanyo sets that don't have this issue at all. Also worth noting, in my experience, TVs with smaller, curved tubes (e.g. 21 inch and under) tend to have the best geometry. It's harder to get perfect deflection on larger sets. Likewise for flat tubes.

BTW, your Siemens will have a Grundig chassis inside. There is a document floating around the internet that shows how Grundig/Blaupunkt/Siemens chassis correspond. The point is you can find the equivalent Grundig model and search up the Service Manual. It's easier to find stuff for Grundig that Siemens or Blaupunkt.

[apfelanni]

if u post  the model and chassis number i can check this out on the equivalent grundig . galaga shouldnt be a big problem .  and paradroid is  right . there is no all for one tv . there are always pros and cons , but with the right monitor ull get arcade pefect .

some 6300 cuc chassis dont like 240 p + resolutions , though the 5xxx cucs can handle them great . and both have a pot on the rear side for vertical linearity and size and a hor coil for hor size  . id the chassis , dl the service manual ( or i ll dropbox it ) and check it out . i m guessing ure playing vertical games on a vertical monitor .