X68K Ace HD minor video issue.

Started by Retro-Rabbit, March 30, 2021, 10:32:51 AM

Previous topic - Next topic



I've been restoring an Ace HD over the past few weeks and everything is going very well aside from a minor video issue.
I've made a DB15 to VGA adapter cable.
I've got a couple older 4:3 LCD screens from the early 2000's and the colors look perfect on them, however they don't have any setting to adjust the vertical height, I can move the image up and down. So I either have the top of the bottom of my Ace's display cut off.

I've got a very good condition 17" CRT monitor that I use with my 486 for retro gaming. If I connect the Ace to that I can see the whole screen, but the contrast is off blacks seems grey, and the colors seem muted. Identical settings on the 486 PC look great.

I've adjusted the contrast and LCD_Mode in Switch.x and messed around a bit with the CRT settings without any improvement. Not sure LCD_Mode does anything like I think it does.
It's odd that the colors look perfect on a 4:3 LCD but the image is cut off, and displays fine on the CRT with muted colors and weird contrast. I've also connected it to a more modern LCD monitor that has a 4:3 mode and the colors are fine, but again the image is cut off. None of the LCD monitors will allow me to change their vertical height.

All 4 screens show either V 31 or 32 kHz(assume a rounding error), and H 55Hz

I've got an XRGB Mini Framemeister, though I've not heard good things about using it with an X68K and an OSSC that likely needs repair or replacement as it no longer outputs anything over HDMI, but boots fine and sees input signals. (built it myself from a kit quite a few years ago)

VGA CRT Monitor issue solved! Bad ground in cable. Color and aspect ratio are perfect now.


I think that unless you can adjust the vertical height you are going to be stuck.

With the OSSC I had to fiddle with one of the 640x modes to alter the v and h sample settings to get it to be vertically centred.


These are my settings for the main, 31KHz mode. Might be useful, but could vary based on your display:

H.samplerate 800
H.samplerate adj 800
H.synclen 98
H.backporch 86
H.active 590
V.synclen 3
V.backporch 39
V.active 512
Sampling phase 180
Allow upsample 2x on
Allow TVP HPLL2x on

Output is Line2x, with scanlines (multiply mode) on at 12-25% - I haven't yet decided whether I want them at the lower end or higher.

I'm using a 1920x1200 Dell Ultrasharp U2410. Of course, it goes without saying that I am *not* stretching the image horizontally to fill the screen - that would just be blasphemy!


I've tried the X68LCDFIX and it works until either the app or game loads a new screen then the settings are lost and the bottom of the screen is missing again.

I still have no idea why the colors on the CRT are washed/muted out and black/no color comes across as grey.

I'll have to order a new OSSC as mine seems busted. It boots fine, sees the input but I get no signal from the HDMI out anymore.