exxos's Atari, Amiga & retro forum

Hey guys,

I'm planning on removing the modulator from this stfm, I'm just wondering if I should remove everything else in the modulator area as well, will I still get my regular RGB ouput.

You'd definitely lose Composite Video. Maybe composite sync too? I don't know.

Why do you want to remove it?

Because I want to remove any device that creates RF off the motherboard. I only want RGB as an output. And I don't like the idea of redundant components being left behind.

I believe that you can remove all the components that are in the box saying "stuffed with the modulator version" in the schematics. And there is an alternative set of components (2 diodes, a transistor and 2 resistors) to get a basic csync signal. It should also be in a box saying "stuffed when no modulator" (well, may be not written like that, and I have the same on the STE schematic that I am studying since last fall).

Yup. Remove it. Turn it into a STf!

EDIT: On the STf it seems that you have to solder in some components if you want to have composite out.

Cheers guyz ;D

DoG wrote: 13 Feb 2021 21:36 On the STf it seems that you have to solder in some components if you want to have composite out.

I'm afraid this will produce only the composite sync signal (required for SCART RGB), not the composite video. Yet RGB SCART requires composites sync, not composite video (which may be used for this purpose), so it is even better.

tzok wrote: 14 Feb 2021 11:19

DoG wrote: 13 Feb 2021 21:36 On the STf it seems that you have to solder in some components if you want to have composite out.

I'm afraid this will produce only the composite sync signal (required for SCART RGB), not the composite video. Yet RGB SCART requires composites sync, not composite video (which may be used for this purpose), so it is even better.

Yup. Thanks for pointing it out. If modulator is present then there is composite video. If not, you have composite sync only. This is the difference between STfm and STf. So if you want to remove modulator you have to solder in a few components to keep sync.

VGA doesn't use composite sync right? It uses hsync and vsync instead if I remember correctly.

Atari SM/SC monitors use H/V sync, same is for VGA monitors, but some 3rd party RGB monitors and SCART equipped TVs require a composite sync. Also Chinese upscalers like GBS8200 and SCART-HDMI converters need it.

All done :)

For anyone interested components were: R215: 10K R216: 150R R217: 100R Q12: 2N3904 CR12 & CR13: LN914 diodes