Getting sound out of an STFM

[Badwolf]

Morning guys,

It's been about 32 years since I had an STFM and back then I would have exclusively used RF out. I'd forgotten it doesn't have any audio out jacks!

I only have an STE monitor cable which expects sound to come from two phono ports.

Given I intend to be debugging YM chip issues, I figure this is an impediment. Short of obtaining *another* cable to lose, is there an easy place to tap audio from on the (preferably top side) of the mobo?

I've foolishly failed to note down board revision, but I think it's one of these: https://www.exxosforum.co.uk/forum/viewt ... 287#p28214.

Ta,

BW.

[Steve]

There should be audio on the monitor jack, you should be able to solder a connector from there. Or buy an ST-VGA adaptor which has an audio jack on it.

[Badwolf]

There should be audio on the monitor jack, you should be able to solder a connector from there. Or buy an ST-VGA adaptor which has an audio jack on it.

Aye, ta.

The AV circuit is quite convoluted. Will have to get out the schematics and a multimeter I think. I was hoping someone would just say "oh yeah, take it from the positive leg of C1234".

I do have an ST-VGA adapter with audio out, but without extreme faff it'll be mono only. I want to run Fronbench. ;)

BW

[stephen_usher]

The STFM is mono only anyway. The STe added stereo

[Badwolf]

The STFM is mono only anyway. The STe added stereo

Mono is better than silence. I have *no* sound ATM.

BW

[kodak80]

Audio comes from the Yamaha YM2149 chip on pins 3, 4 and 38 and is combined to create mono audio to the 13 pin video port.

You could always add this modification for stereo

post-119-1046377364.gif

[sety]

Just use RF (even with a modern TV) and hit tune...

And enjoy the anticipation of waiting for your game to come out of the hash and be ready to play. :)

[Darklord]

You could always do the small audio mod I did to my Mega ST4
and bring the sound out to a cheap set of powered speakers.

It really does make a BIG difference in the sound! :)

https://www.exxosforum.co.uk/forum/viewt ... +audio+mod

HTH's.

[Elethiomel]

The AV circuit is quite convoluted. Will have to get out the schematics and a multimeter I think. I was hoping someone would just say "oh yeah, take it from the positive leg of C1234".

When I did my audio out mod on my ST I pulled the signal from C12. See the red wire in the attached.

20220520_220933.jpg

[Badwolf]

When I did my audio out mod on my ST I pulled the signal from C12. See the red wire in the attached.

That's perfect, thanks. I've just managed to find the right schematic and that ties in exactly with my board and your example.

Cheers!

BW