31Khz CRT gets squashed image

[Slypty]

I'm using a NEC 3D which can do 15-31Khz, so that's great but I'm only able to view a full image in 240p mode. Once I turn on the forced scandoubler, what ends up happening is the image only covers about 75% of the screen. I've been tinkering with .ini settings with no luck so far. Anyone have some insight what I could try?
It's a 1024x768 native resolution, with that setting nothing changes. I can also toggle direct video on or off, with no changes. I have it On since I'm using an HDMI to VGA converter.

Here's my current .ini settings:

[MiSTer]
key_menu_as_rgui=0 ; set to 1 to make the MENU key map to RGUI in Minimig (e.g. for Right Amiga)
forced_scandoubler=1 ; set to 1 to run scandoubler on VGA output always (depends on core).
ypbpr=0 ; set to 1 for YPbPr on VGA output.
composite_sync=1 ; set to 1 for composite sync on HSync signal of VGA output.
vga_scaler=0 ; set to 1 to connect VGA to scaler output.
hdmi_audio_96k=0 ; set to 1 for 96khz/16bit HDMI audio (48khz/16bit otherwise)
keyrah_mode=0x18d80002 ; VIDPID of keyrah for special code translation (0x23418037 for Arduino Micro)
vscale_mode=0 ; 0 - scale to fit the screen height.
; 1 - use integer scale only.
; 2 - use 0.5 steps of scale.
; 3 - use 0.25 steps of scale.
vscale_border=0 ; set vertical border for TVs cutting the upper/bottom parts of screen (1-399)
;bootscreen=0 ; uncomment to disable boot screen of some cores like Minimig.
;mouse_throttle=10 ; 1-100 mouse speed divider. Useful for very sensitive mice
rbf_hide_datecode=0 ; 1 - hides datecodes from rbf file names. Press F2 for quick temporary toggle
menu_pal=0 ; 1 - PAL mode for menu core
hdmi_limited=0 ; 1 - use limited (16..235) color range over HDMI
; 2 - use limited (16..255) color range over HDMI, for VGA converters.
direct_video=1 ; 1 - enable core video timing over HDMI, use only with VGA converters.
fb_size=0 ; 0 - automatic, 1 - full size, 2 - 1/2 of resolution, 4 - 1/4 of resolution.
fb_terminal=1 ; 1 - enabled (default), 0 - disabled
osd_timeout=30 ; 5-3600 timeout (in seconds) for OSD to disappear in Menu core. 0 - never timeout.
; Background picture will get darker after double timeout
osd_rotate=0 ; Display OSD menu rotated, 0 - no rotation, 1 - rotate right (+90°), 2 - rotate left (-90°)
vga_sog=0 ; 1 - enable sync on green (needs analog I/O board v6.0 or newer).

[thorr]

Just a few thoughts, not knowing the exact monitor you are using...

• Not sure why you would want to use forced_scandoubler when the monitor supports the native signal.
• Perhaps the monitor has resize controls. If they are digital, it might have different memories for different modes. If they are knobs, then you would have to adjust them each time you use a different screen signal.
• Try using the scaler with various video modes like 1024x768 and 640x480 and see how it fills the screen in comparison. Maybe other modes are squished too.

[Slypty]

NEC JC-1404HMA
https://crtdatabase.com/crts/nec/nec-jc-1404hma

I'm trying to run everything at 480p with forced_scandoubler, mainly so I can use it to rotate shmups.
Any resolution I've tried just ends up squashed in 480p mode for some reason, the resize controls are just front buttons, and they work but it's maxed out currently.

Guess I'm just out of options for a fullscreen 480p mode.

[naylord]

I'm wondering if it's a mix of scandoubling with direct video; like it just increases the line count but then just centers the original video inside of the larger resolution rather than drawing every line twice (which is what scandoubler does on the analog out)