Vintage Synth Repair

On Friday 30 June 2006 07:53 am, sputnik979 wrote:
> 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.

I believe I *have* a 5514 (only it's LC5514, I think made by Sanyo) around 
here someplace,  but that may not be your problem.  I read a page on the 'net 
somewhere that discussed cleaning up a unit that had suffered from battery 
corrosion problems,  and it was quite extensive,  with traces being eaten,  
plated-through holes being a problem,  etc.  You may want to do some more 
digging there.  Perhaps the write signal is not getting to the chip?  
Something like that in any case.  The worst part about battery leakage 
corrosion is that it gets into places you can't see,  under parts and such.  
Go at it with a meter and verify your connections,  and make sure that there 
really _are_ connections where there are supposed to be.

-- 
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
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