Software Support > GroovyMAME
Do switchres monitor presets always display game content in some form?
Zebidee:
You have "overscan". Almost every TV as this issue. When people watch TV they don't like seeing black, unfilled parts of the screen. So TVs are designed to make the picture a little larger. Sucks for gaming. Arcade monitors have pots so you can tweak the size to suit the game, TVs have little of that. The exact options available depend on your TV. Best place to start looking is in the TV's service mode.
For the TV - Every TV is different, but generally you can find service menu controls to vary vertical height & position, and horizontal position. Horizontal width control is sometimes possible, but probably not. You may have some other geometry controls for stuff like pincushioning.
--- Quote from: nix999 on December 02, 2025, 03:24:23 pm ---These two ranges make every game I started thus far run ~100%
crt_range0 15600-15800, 49.50-50.20, 2.000, 4.700, 5.800, 0.064, 0.192, 1.056, 0, 0, 192, 288, 448, 576
crt_range1 15600-15800, 59.30-60.50, 2.000, 4.700, 5.800, 0.064, 0.192, 0.898, 0, 0, 192, 248, 448, 480
--- End quote ---
For PC - You can trim back some of the horizontal width & position by modifying the front and back porch settings, which I've bolded above. You may find that different settings optimal for "NTSC" vs "PAL". You don't really get any control over vertical size with CRT_emulator.
Given all these limitations, I often dive right in and change the TV's width capacitor! This is a large polypropylene capacitor near the flyback, HOT (horizontal output transistor) and yoke coils connector (visible in background of photo below). Obviously TVs vary, but it is usually a value like 384, 474, 564, usually rated for high voltage, typically 400v or higher. Substituting a slightly larger value brings the picture in a little.
In the example photo below, from an RGB mod of a JVC TV I did earlier this year, I swapped a 474 400v for a 684 630v, and this brought the picture in by around 1.5cm. For more detail, see my writeup of the JVC TV mod. I have probably also discussed it in earlier TV mods, if you want to look through them.
In terms of capacitor codes, pay attention to the "XX4" format - the number is capacity in nanofarads (nF) and "4" means number of zeros. So a 564 means 560,000 nF. Point is to stay close to that level, use a capacitor of similar but different value. For example, if you have a 474 cap, don't replace with a 473, but a 684 is probably fine. It is OK to sub in a capacitor with a higher voltage rating, but don't go lower than the original.
Also, be sure to use the same kind of capacitor (polypropylene in this case). You can buy kits of these capacitors (range of various values) from Aliexpress and similar. I recall walking the street in Bangkok's electronics district to see an old woman, with no teeth and a big smile, presenting a trestle table covered with these capacitors in bags of various values. Like she was selling bananas. Anyway...
Hacking your TV is obviously "risky" and taking it to the next level - not for everyone. However, I have done this particular hack around a dozen times and all is good. I don't know of a better way to reduce the built-in overscan in many TVs. Just don't blame me if something goes wrong! :D 8)
nix999:
Ok ... I'll try tweaking the bolded values and I'll see how far it will take me.
But I'm wondering now ... if the xml tag triggers switchres to generate a 'perfect' modeline the 2nd time it must be possible to tweak crt_range0 and crt_range1 to immediately generate the 'perfect' mode the first time?
And crt_rangeX does not allow me to control the vertical height and position then? Probably the absence of the CRT V size is related to that ...
Perhaps the service menu could help indeed ... or a combination of things.
As for the soldering ... That's out of my league ...
The last thing I soldered was a new battery in a razor and it fried near instantly upon attaching it to the grid. :o
I should have been easy but apparently the electronics in the charger didn't agree.
So that being said opening a television and soldering other stuff in it just might trigger my funeral.
I'm a programmer not an electrotechnician. I've always wanted to learn some electronics later in life but until now it just didn't happen.
Real life always intervenes.
Thank you for your valuable feedback.
Zebidee:
We do what we can :D
Good luck and take care.
Calamity:
Hi nix999,
--- Quote from: nix999 on December 03, 2025, 02:01:50 pm ---But I'm wondering now ... if the xml tag triggers switchres to generate a 'perfect' modeline the 2nd time it must be possible to tweak crt_range0 and crt_range1 to immediately generate the 'perfect' mode the first time?
--- End quote ---
Of course it is, all the geometry options do is to modify the default params in the crt_range line. The idea is to build a crt_range that gives the correct geometry first, and then only apply the UI tweaks in edge cases.
--- Quote ---And crt_rangeX does not allow me to control the vertical height and position then? Probably the absence of the CRT V size is related to that ...
--- End quote ---
You can control the vertical position, but not the vertical height (or v-size). This is not a limitation of the software, but a real feature of the CRT technology. V-size control requires electrical adjustments happening inside the monitor that we can't request through the video signal itself.
makya:
I have a TRINITRON too, chassis FE-1A, I heard this is an easy one, at least easier than most other SONY's chassis of that era. It can sync any signal I had try, between 50-60, like R-TYPE, Mortal Kombat, Xexex or Psychic 5, but not without tinkering first.
Anyway, maybe it's just this set but, I found that going from 50Hz to 55Hz, synchronization is successful most of the time, while going from 60Hz to 55Hz is much less likely.
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