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System 80b/Robo-War help needed
- Thread starter ronsplooter
- Start date
I am interested to know.
Glad it's fixed,got excited initially as I thought the vid would be a fault finding vid
OP
OP
I'm sure Jim will respond with the details but when I get some spare time I'll turn all of our back and forth messages where he got me to try different things into a post on this thread as there could be useful info for the future 
Ok so Chris doesn't know this yet (a small surprise coming!), but I received his 80b sound board a few days ago to have a look at this crackle fault, after we'd spent a few weeks going back and forth with me suggesting things to try/change to solve it!
So have been spending the last 2 days on this trying to track down this blooming annoying fault. What an absolute PITA this has been!!!
So here it is - > FIXEDNow need a few beers! and some counciling
Glad it was fixed by Jim - awesomework there mate.
Mind you if all else had failed at least PBR had them for $100 - tho much better to save the original
Poibug
I am interested to know.
Glad it's fixed,got excited initially as I thought the vid would be a fault finding vid
I'm sure Jim will respond with the details but when I get some spare time I'll turn all of our back and forth messages where he got me to try different things into a post on this thread as there could be useful info for the future
I was out on a road trip today and so didn't have time to reply with an great detail earlier, just to say quickly that a rom swap wasn't the complete solution. I only got back in at 9pm tonight.
The issue was tracked down to a combination of items.
1) A bad or failing DAC ic at E2
2) A bad or failing OP amp at A5
3) A partially corrupt/damaged Sound D1 rom at K2
4) New Tantalum caps at C33 & C34 (possibly not needed for this fault but worth doing anyway)
5) New 1uf non polarised Cap as C37 (possibly not needed for this fault but worth doing anyway)
I am still learning things about this hardware myself, as the music is made from both sides of the sound board with the drum beat part being either created or processed form the sound/speech section. It is interesting as well that if you remove the music rom then the drum beat does not function, even though it appears to be created from the D1 sound rom. Sound effects still function though. Further more if you remove the H1 op amp then the drum beat still functions so it isn't generated from either of the Ay chips.
I am planning to write a much more detailed document on this hardware some day on my site, as there has been a lot learnt from developing my new sound board to.
I hope this helps.