[sdiy] A20G545 chip, what is it?

Nathan Trites nathan at idmclassics.net
Sun Jun 19 20:57:32 CEST 2022


There certainly are pictures of plastic SSM ICs with similar datecode lines
and lettering just as wonky so that could be it...
https://www.ebay.com/itm/192742272128
https://picclick.com/SSM2033-VCO-chip-NOS-Korg-MP4-Monopoly-etc-332999604291.html

Nathan

On Sun, Jun 19, 2022 at 10:54 AM John Speth via Synth-diy <
synth-diy at synth-diy.org> wrote:

> I don't think it was an LM389 (audio power amp) but that got me thinking:
> Could it be a mismarked SSM2033? The pin count matches and the power
> connections (the only connections wired) are consistent with the data
> sheet. Sometimes shipments to manufacturers are marked according to the
> buyer's specs (obfuscation, custom variation, etc). I can't remember from
> whom I was buying my small quantity SSM chips at the time. There were not a
> lot of retail mail order sellers back then. - JJS
>
> On Sunday, June 19, 2022, 07:14:38 AM PDT, Mike Bryant <
> mbryant at futurehorizons.com> wrote:
>
>
> Possibly an LM389 transistor array equivalent
>
>
>
>
>
> *From:* Synth-diy [mailto:synth-diy-bounces at synth-diy.org] *On Behalf Of *John
> Speth via Synth-diy
> *Sent:* 19 June 2022 14:58
> *To:* SDIY
> *Subject:* Re: [sdiy] A20G545 chip, what is it?
>
>
>
> Photo at: https://myplace.frontier.com/~jspeth/A20G545.JPG
>
>
>
> I should have posted this pic first. The date code accurately indicates
> when I built it: 1983. So anything with origins past that date are not
> valid.
>
>
>
> Thanks - JJS
>
>
>
> On Sunday, June 19, 2022, 06:05:02 AM PDT, <synth1 at airmail.net> wrote:
>
>
>
>
>
> I'm pretty good at this if I can SEE a photo.
>
> Paul S.
>
>
> -----Original Message-----
> From: Synth-diy <synth-diy-bounces at synth-diy.org> On Behalf Of brianw
> Sent: Sunday, June 19, 2022 3:16 AM
> To: John Speth <johnspeth at yahoo.com>
> Cc: SDIY <synth-diy at synth-diy.org>
> Subject: Re: [sdiy] A20G545 chip, what is it?
>
> My first guess was a 74x545 octal bidirectional transceiver, non-inverting.
> They're 20-pin.
>
> However, that doesn't seem to fit on a SSM voice card (or into an 18-pin
> package).
>
> Brian
>
>
> On Jun 18, 2022, at 7:59 PM, John Speth wrote:
> > Today I was dumping old circuit boards that I built many years ago. I was
> stripping valuable parts from one and I found two 18 pin DIPs that are
> marked "A20G545" on one line and "MCE 8211" on the line below it. 8211 is
> the date code (1982). The other markings are a mystery. Searching for this
> chip online was a dead end for me. Does anybody know what it could be? It
> was from a board that contained an SSM 2012 VCA and an SSM 2044 VCF. I've
> lost the schematics. It was my design.
> >
> > Thanks - JJS
>
>
>
>
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