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@yahoo.com>
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
>
>
>
>
>
>
>
>
>
> PolySix "Digiest" Page: http://www.acc.umu.se/~amber/Poly6
> Yahoo! Groups Links
>
>
>
>
>
>
>
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