Weird ASIC observation.

[ThreeFingersOfLove]

So,

I opened my A6 today and I took some photos. I remembered some time ago, that a certain voice (I think it was either voice 15 or voice 16) was behaving a little strangely, in some sounds and in certain areas of the keyboard. I tuned it, re-tuned it, everything was tuned properly and there was still this little modulation going on.

Anyway, as I said, I inspected the analog board with the analog chips and I have found that:

for Oscillators 1-16, the chip is called Alesis ASO 0220A
for Filters 1-14, the chip is called Alesis ASF 0220A
and for Filters 15-16, the chip is called Alesis ASF 0150A, (different from the previous ones).

All chips except this one are marked with a marker.



I would like to know if the different chip causes either Voice 15 or 16 to mis-behave. Maybe Mike Peake can shed some light here?

[husker]

That number is the date code of chip manuafacture - Year and week

0220 is the 20th week of 2002
0150 is the 50th week of 2001

Given your description I would say that the original ASF chip was replaced with the 0150 at some point. This could have happened during original manufacturing if a fault was found during testing. It may just be the 'spares' were an older batch - and could indeed behave differently from the 0220 batch. The solder on the 0150 also looks 'less clean' thatn the other chips which means it was soldered individually rather than the wave soldering during the orginal assembly.

I would say it makes your A6 extra valuable as you have 'extra character' in your 15/16 voices

[ThreeFingersOfLove]

Thanks a lot! That cleared things up.