Likely IC2/IC3 were ROM (read-only) sample memories - both contained the exact same wave samples.
Yamaha's ROM IC supplier (IC chip maker) probably migrated from the larger SOIC (small-outline integrated circuit) to the smaller TSOP (Thin small-outline package) ROM. Most ROM and Flash memory use TSOP (or smaller) these days.
-Mike
--- In AN1x-list@yahoogroups.com, Apuhjee <apuhjee@...> wrote:
>
> Seems the mystery has been solved. I have both Revision B (with IC2) and Revision C (with IC3) so it seems that the PCB was designed with two different chips in mind. My guess would be to deplete inventory of one first, without requiring two different PCB production runs. It must be so cool to be Yamaha :)
> Â
> Cheers ~ jp
>
> "I like mathematics because it is not human and has nothing particular to do with this planet or with the whole accidental universe â" because, like Spinoza's God, it won't love us in return." ~ Bertrand Russell
>
> --- On Fri, 1/8/10, apuhjee <apuhjee@...> wrote:
>
>
> From: apuhjee <apuhjee@...>
> Subject: Re: [AN1x] New PLG150-AN ... Where is IC2???
> To: AN1x-list@yahoogroups.com
> Date: Friday, January 8, 2010, 6:31 PM
>
>
> Â
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>
> I've uploaded a (somewhat crappy) picture of both cards - one with / one without IC2. They both work fine, so I'm -really- curious what this chip's purpose is.
>
> jp
>
> --- In AN1x-list@yahoogrou ps.com, Jeff <jf.serviere@ ...> wrote:
> >
> > Beware of a REALLY missing I.C. !! In case your sound card would not
> > work properly or at all ...
> > Cheers.
> > J.F.
> >
> > apuhjee a écrit :
> > >
> > > The new card I just bought is missing the center IC (my first card
> > > from 10 years ago has it)... I'm sure there's a good reason why it's
> > > no longer needed, but does anyone know what that reason is?
> > >
> > > Cheers ~ jp
> > >
> > >
> >
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