Omega msx audio problem

Supporter (4)

15-03-2023, 20:55

hi I've built an omega msx and it works well but there's no audio when playing games, the only audio I get is from keyboard strokes. I've checked the AY-3-8910 PSG chip, there's the clock signal working and checked the 3 audio channels with my oscilloscope, also checked the Op amp which seems to be fine.. Any idea on what else I could check?

Using a Carnivore2, with a pal rom, (cbios, msx2)

https://github.com/skiselev/omega/blob/master/Mainboard.md

Por Pentarou

Hero (559)

15-03-2023, 21:32

When you write "checked the 3 audio channels", do you mean you checked with the scope and there's audio coming out from the PSG?

Por yobbo89

Supporter (4)

15-03-2023, 21:36

Yes, later on i will get some screen grabs of the signal from my scope if it helps

Por Pentarou

Hero (559)

15-03-2023, 21:43

From the PSG to the AMP there's only R34, C72 and R26.
I would follow the audio path, from the PSG to the AMP, probing with the scope on those parts.

Por yobbo89

Supporter (4)

18-03-2023, 08:19

i ordered another 8910 , cost me $6 , alot of people want $20+ for the yamaha on ebay....

I thaught i had some signal on some of the audio out channels,i guess not ,
all the da0 - da7 had strong signals on the chip

i had a look at u44 74ahct02 ,a0-a1 seem fine but psg bc1 looks a little odd . i did try another chip in u44

i could build this to realy test the chip on another device but i'll try a another chip first .
http://www.florentflament.com/blog/driving-ym2149f-sound-chi...

Por yobbo89

Supporter (4)

25-03-2023, 14:02

This problem is solved, replacment AY-3-8910 PSG worked, rom chip still erases over time, I'll make a thread later.