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Vintage Synth Repair

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RE: [vintagesynthrepair] obsolete component part sourcing

2008-05-20 by Scott Nordlund

This is a (drastic) modification rather than a repair, so it's not a stock part. The stock part is a 21256 256K x 1 bit DRAM, and I am attempting to replace it with a larger SRAM (with latches to separate the row and column addresses and a banana jack patch bay to make all address lines available for arbitrary rearrangement).

I have several part numbers that I'm looking for- NEC UPD444001 or UPD434001, Hitachi HM621400H, Toshiba TC551402J, and maybe (haven't found a datasheet to confirm) Mitsubisihi M5M54R01. DIP package would be nice, but probably I'll have to settle for SOJ-32. Any variant on these would work as long as it's 5V and big enough to be soldered by hand. The speed rating isn't important (as the original chip is considerably slower).

There is a smaller (1M) and rather expensive chip available from Digikey, and I can settle for this if necessary, but it won't be quite as amazing as a 4M chip. I have also found a 16M 3.3V chip. The biggest problem here is finding a 54 pin TSOP-II to DIP adapter for a sane price.


To: vintagesynthrepair@yahoogroups.com
From: russrose@mindspring.com
Date: Mon, 19 May 2008 19:27:23 -0400
Subject: Re: [vintagesynthrepair] obsolete component part sourcing

what's the manufacturer part#?what's the yamaha part#?

On May 19, 2008, at 5:50 PM, Scott Nordlund wrote:

I'm looking to get a rather unusual SRAM chip (4M x 1 bit, 5V, asynchronous, parallel interface) for a project I'm working on (Yamaha VSS-200). These chips were produced by several companies, but they're all obsolete now and all the stock seems to have been bought by "$250 minimum order, send request for quote" type places. Does anyone know of any possible alternative source for these (I tried all the usual suppliers that I could think of- mouser/digikey/jameco/etc.) or any clever way to trick someone into selling single/small quantities for a reasonable price?

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