exxos's Atari, Amiga & retro forum

Okay, I've got a specific need that I'm pretty sure someone around
here has already done at some point in time.

I use my Mega ST4 and SC1224 monitor to run my BBS, DarkForce.

I'd like to do a small audio mod to bring sound out via a plug (1/8th?)
to a small set of speakers.

Reason being, to hear pages from the "Chat" option on the BBS requires
that the monitor be on 24/7. I don't like that, even if I'm using the screen
saver.

With a mod like that, I could leave the monitor off but still hear the bell for
Chat pages.

Thanks.

Just slap a audio jack on the RGB port sound output pin and run a normal 3.5mm audio cable to a small pair of active PC speakers..

exxos wrote: 25 Apr 2021 01:04 Just slap a audio jack on the RGB port sound output pin and run a normal 3.5mm audio cable to a small pair of active PC speakers..

Right. So pin 1 is audio and pin 13 is ground, and when you say active you mean powered or amplified, right?

Thanks!

Darklord wrote: 25 Apr 2021 17:22 and when you say active you mean powered or amplified, right?

Yep.

Thanks again. :)

Hmm, had my Mega ST apart yesterday and from what I can see, the black
plastic cover over the video connector would make it extremely hard for
a klutz like me to get to those 2 pins.

Can they be pulled from an easier place on the motherboard?

If not, does anybody sell a ready made ST video cable with audio out?

Thanks all.

You could mod the monitor, adding a jack socket connected to the input from the cable. As you don’t need amplification within the monitor it wouldn’t need to be powered to work. No need to cut wires as you’d merely solder a couple of new ones.

Darklord wrote: 20 May 2021 05:39 ...
Can they be pulled from an easier place on the motherboard?
...

Minus side of C35 is Audio out on MegaST4. And GND where ever. Otherwise one of these?

Excellent. I'll look that over next time I have it apart.

Hmm, about that link - don't want to switch to a VGA monitor from
the SC1224 unless I have to, but I'll keep it in mind.

Thanks!

Okay, finally got a chance to work on this some more.

I'm not good at reading schematics. Period.

Here is a snapshot of my Mega ST4's motherboard, zoomed in on C35.

While I think the + side seems obvious, the - side is not to me. C35 is
beside C34 and there are 3 solder pads opposite the + symbols for
each.

Can someone more experienced please draw an arrow pointing directly
(and exactly) to the one I'm supposed to solder the + wire from an RCA
jack to?

Thanks, much appreciated.