To everyone that participated in this bulk order - I have some potentially bad news. Lemonhorse, who has been designing the AY-3-8912 board recently contacted me regarding the sound chips for this bulk order. Here is what he had to say:
Hi frailn,
I think there is a big problem: now that i’ve checked the AY 3 8912A/P - 9151 CCA chips in depth I detect that none of my 4 chips are able to add NOISE to Tone A, B or C. My first check was quick and dirty I just checked the Tone A B and C and the Envelope.
I think You should now that first.
I Don’t know - if it matters:
my 2 reference chips are named:
GI - AY 3 8912 8311 CDA
the new chips are named:
microchip - AY38912A/P 9151 CCA
I’m sorry for that bad news.
I’m not sure if this means all the chips we ordered have this issue. But, I think it is only fair to let you know what Lemonhorse discovered this week when testing the four chips I shipped to him.
Here are my next steps:
I’m doing some research to find out if this problem has been documented on any other website or forum. I don’t know if the mixing issue is by design or a flaw. I would like to find out.
If I don’t find any info in step one, or if I discover that it is not a design issue, I’m going to send my two chips to Lemonhorse to test.
Depending upon the results listed above, I may ask my seller for refund. However, this may be difficult since the chips have been spread to the four corners of the earth.
My guess at this point is that we have a version of the chip that doesn’t mix noise with the tones. Maybe this new-old-stock was designed for a particular company and they were trying to save money by cutting back on features? All just a guess, really. I’ll keep you updated as I progress in my research.
If you have any input, questions or assistance along these lines, please speak up!
My 2 cents: Don’t worry about refunds too much, if you manage to find out what the problem is (design change, revision problems, …) that’s all that I’d be interested in
I spent an hour this morning running google searches on different variations of AY 3 8912/noise/mixer/tone/issues/etc… without any luck. The schematics and information I have found always lump the 8910/8912/8913 together when outlining information regarding the way tone/mixer/noise work together. There is no information I can find regarding the differences between manufacturing runs.
Since the noise/tone mixer is controlled by internal workings of the chip, and since all four of the chips I sent to Lemonhorse have the same issue, I’m inclined to think the problem is related to a particular manufacturing run.
For now, I’m open to suggestions on figuring out the source of the issue. I may be limiting myself on figuring this out due to a lack of experience.
Well if you are not in too much of a rush things work out. My 2 chips came today. What a long wait but you notice how no one freaked out or anything. I think my package was in the same box as wilba’s package
Some no-news about the noise problem. Microchip tech service was unable to find a reference datasheet for their version of the ay-3-8912 chips. And in other way, Sergey Bulba ( http://bulba.untergrund.net ) never met that problem… he gave me the email of another guy but i still did not contact him however.
I have the soundchips in a shoe box but not enough time for now to build the synth :-\
