Discussion about the Korg PolySix synthesizer

Hi !
The case is that it is my tech who's doing all the dirty work ;) I'm 
just managing & providing insights, let's call it. He has schematics 
and he knows what he's doing; he replaced the bad SN chips and 
resoldered all the bad traces so that now all formerly dead functions 
like octave switching, subosc, ADSR, cutoff, attenuator work fine. 
Now he's sort of asking me what to do, because all the traces seem 
fine, and this one IC is diffferent from others in the way of keeping 
4V. So we have a complementary cooperation here as you see ;)
And the question of random patches/values:
If I create let's say a deep bass patch and save it to a given 
location - the 'deep bass' is there, as long as you don't change 
presets... so the random stuff appears only when you come back to 
read out the patch. So I guess the values don't even make their way 
to the storage device?




--- In PolySix@yahoogroups.com, "Roman" <modular@...> wrote:
>
> hi,
> I don't think your RAM is damaged, try to find broken traces on the 
PCB
> leading to it. If some of them are damaged by battery leakage, 
writing a
> patch will actually write random stuff to the RAM, same thing when 
trying to
> read a patch. It's OK for RAM to work at smaller voltage, because 
it's
> powered via diode. Although I'd expect something like 4.5V and not 
4.
> It's hard to find replacement chip. I made a small adaptor, that 
takes
> typical RAM and converts to TC5514 pinout, pictures included.
> BTW, desoldering RAM can add more damage to the board if you're not
> carefull. OTOH it can fix some problems if there was some 
intermitent
> contact at some of the RAM leads.
> 
> Roman
> 
> ----- Original Message -----
> From: "sputnik979" <sputnik979@...>
> To: <PolySix@yahoogroups.com>
> Sent: Tuesday, June 27, 2006 8:43 PM
> Subject: [PolySix] Memory failure, S-RAM suspected.
> 
> 
> > Hi folks!
> >
> > My Polysix after battery leakage had the typical symtomps you 
might
> > expect.
> >
> > After having cleaned & resoldered the guts everything's fine 
apart from
> > the memory;
> > I create a patch, I press WRITE, I choose the location. Seems OK. 
But
> > just click another patch, then come back to the one I just saved -
 and
> > it's not there. A new 3.6V battery has been installed, but it is 
not
> > the matter of battery, beacause we are talking about doing this 
when
> > the synth is still operatnig, being plugged, so it has all the 
power
> > needed all the time.
> >
> > I'm inclined to think the TC5514 S-RAM chip is the culprit, 
because all
> > the chips keep voltage of 5V whereas this one has just 4V.
> >
> > What do you think ? What replacement part for TC5514 should I 
look for?
> > I've heard about Intersil HM6514 and Nec uPD444c (D444C-6514) but 
are
> > these really the only ones? I came across some chips 
with 'similar'
> > characteristics and I really would like to avoid importing the 
above
> > mentioned ICs.
> >
> > I'm not a tech, but a tech's opinion would be greatly appreciated 
and
> > helpful.
> >
> >   cheers
> >   aero