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Video card III FMT-418

Started by hyrulebr, December 23, 2017, 08:12:52 AM

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hyrulebr

Hi

I bought one Fm Towns Fresh FT from YAJ and it's working fine!  ; ;D

This model already have a VGA 15 pin video out so 15hz and 24hz are converted to 31hz.

But I have 3 monitors that support 15hz and wants to try it out. I also bought video card III FMT-418 (to bypass converting to 31hz) but I can't get any sync for the 3 monitors! Two I got no image at all (and both are X68000 compatible in 15hz  >:( ) and the third I can get a blinking, rolling  image, withy the message no sync. The rolling effect is because this third monitor can only sync sources with just one sync signal (C sync) and  VGA have H+V sync. But I tried 4 extron RGB interfaces that mixed H + V into just one sync signal (works for dreamcast and X68000 signal) and same rolling, blinking image. Since either Extron RGB interfaces cannot get sync and also the monitors in direct connection (without the Extrons) I think or the Fm Towns have a weird sync or my video card is broken.

Anything I can check in the video card? This model is the one without knobs for adjust picture card (I have to adjust it in towns OS but didn't figure out yet).

SuperDeadite

You probably need to make a custom cable for this.
On newer units like your Fresh, the internal video output is RGBHV. (Sync is pins 14 and 15)
However, the video card is old Towns style, meaning RGBS. (Csync is pin7, pins 14 and 15 are not connected)

Official Fujitsu Towns monitors from the Fresh generation have hardwired video cables and are wired for both.


hyrulebr

Looking at FM towns pinout make all the sense:

https://www.gamesx.com/wiki/doku.php?id=av:japanese_rgb-15

Thank you!  :)

Another question:

I realized that FM towns can display video in both outputs simultaneously. Is it okay to do this?

skpstmgs

Sorry for the slight off-topic, but this topic got me wondering if there is a video card that fits into the Model 2 FMT that outputs 31KHz so you don't have to use an external scaler to use on a modern CRT?

hyrulebr

Quote from: SuperDeadite on December 23, 2017, 06:47:19 PM
You probably need to make a custom cable for this.

I have two of these adapters and seems to be a easy mod (even for a unknow person to the iron solder  ::)). Just swap wire in pin 14 to pin 07 in the RGB-15 connector side:

http://retrocables.es/tienda/index.php?id_product=187&controller=product&id_lang=1

The modded adapter cannot be used with X68000 anymore and I'll have to stick a warning: DO NOT USE WITH X68000. Pin 7 in X68000 have a 5v signal and will be very dangerous to send it to sync line in vga side....

hyrulebr

Quote from: hyrulebr on December 23, 2017, 09:20:52 PM
I have two of these adapters and seems to be a easy mod (even for a unknow person to the iron solder  ::)). Just swap wire in pin 14 to pin 07 in the RGB-15 connector side:

http://retrocables.es/tienda/index.php?id_product=187&controller=product&id_lang=1

The modded adapter cannot be used with X68000 anymore and I'll have to stick a warning: DO NOT USE WITH X68000. Pin 7 in X68000 have a 5v signal and will be very dangerous to send it to sync line in vga side....

It worked! Thanks Superdeadite!   :D