128k 6U sound issue

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OldsMan
Posts: 1
Joined: Sun Mar 26, 2023 9:39 am

128k 6U sound issue

Post by OldsMan »

Hi,

I'm fighting with a 6U : no sound on the AY chip.
Everything is working, 128k games are running, but no sound .
Keyboard klick and beeper sound works fine.

I have replaced the ULA, the ROM and the AY ( from 100% working device ) , still the same.

Checked the AY pin1 ( analog C ) with a simple test program on a working and on this non working speccy, looks the output is different.
Working:
https://youtu.be/5q1a06ZbnSk

Not Working:
https://youtu.be/gfHAUPlBIvc

https://youtu.be/jaTgQVv6EOU

Also interesting, on the AY test pin I have nice square signal, but on the non working one.

Any idea what to check?

Thanks!
Attachments
Spectrum 128k AY d0 working
Spectrum 128k AY d0 working
Spectrum 128k AY d0 non working
Spectrum 128k AY d0 non working
Spectrum 128k AY test pin2 non working
Spectrum 128k AY test pin2 non working
Spectrum 128k AY test pin2 working
Spectrum 128k AY test pin2 working
McKlaud
Posts: 337
Joined: Tue Dec 19, 2017 10:02 pm
Location: St Albans, UK

Re: 128k 6U sound issue

Post by McKlaud »

Check if 1.79MHz clock coming to the PSG.
Claudius
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