Small audio mod?

General discussions or ideas about hardware.
User avatar
Darklord
Posts: 900
Joined: Wed Sep 20, 2017 1:41 pm

Small audio mod?

Post by Darklord »

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.
Welcome To DarkForce! www.darkforce.org "The Fuji Lives.!"
Atari SW/HW based BBS-Telnet:darkforce-bbs.dyndns.org 1040
User avatar
exxos
Site Admin
Site Admin
Posts: 23488
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: Small audio mod?

Post by exxos »

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..
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
User avatar
Darklord
Posts: 900
Joined: Wed Sep 20, 2017 1:41 pm

Re: Small audio mod?

Post by Darklord »

exxos wrote: Sun Apr 25, 2021 1:04 am 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!
Welcome To DarkForce! www.darkforce.org "The Fuji Lives.!"
Atari SW/HW based BBS-Telnet:darkforce-bbs.dyndns.org 1040
User avatar
exxos
Site Admin
Site Admin
Posts: 23488
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: Small audio mod?

Post by exxos »

Darklord wrote: Sun Apr 25, 2021 5:22 pm and when you say active you mean powered or amplified, right?
Yep.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
User avatar
Darklord
Posts: 900
Joined: Wed Sep 20, 2017 1:41 pm

Re: Small audio mod?

Post by Darklord »

Thanks again. :)
Welcome To DarkForce! www.darkforce.org "The Fuji Lives.!"
Atari SW/HW based BBS-Telnet:darkforce-bbs.dyndns.org 1040
User avatar
Darklord
Posts: 900
Joined: Wed Sep 20, 2017 1:41 pm

Re: Small audio mod?

Post by Darklord »

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.
Welcome To DarkForce! www.darkforce.org "The Fuji Lives.!"
Atari SW/HW based BBS-Telnet:darkforce-bbs.dyndns.org 1040
User avatar
stephen_usher
Posts: 5578
Joined: Mon Nov 13, 2017 7:19 pm
Location: Oxford, UK.
Contact:

Re: Small audio mod?

Post by stephen_usher »

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.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
User avatar
DoG
Posts: 1125
Joined: Sat Apr 07, 2018 12:26 pm

Re: Small audio mod?

Post by DoG »

Darklord wrote: Thu May 20, 2021 5:39 am ...
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?

MegaST4 Audio out tap.gif
MegaST4 Audio out tap.gif (95.37 KiB) Viewed 3681 times
User avatar
Darklord
Posts: 900
Joined: Wed Sep 20, 2017 1:41 pm

Re: Small audio mod?

Post by Darklord »

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!
Welcome To DarkForce! www.darkforce.org "The Fuji Lives.!"
Atari SW/HW based BBS-Telnet:darkforce-bbs.dyndns.org 1040
User avatar
Darklord
Posts: 900
Joined: Wed Sep 20, 2017 1:41 pm

Re: Small audio mod?

Post by Darklord »

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.

P1010023.JPG
P1010023.JPG (149.98 KiB) Viewed 3032 times
P1010020.JPG
P1010020.JPG (216.93 KiB) Viewed 3032 times
Welcome To DarkForce! www.darkforce.org "The Fuji Lives.!"
Atari SW/HW based BBS-Telnet:darkforce-bbs.dyndns.org 1040
Post Reply

Return to “HARDWARE DISCUSSIONS”