Failure of the POKEY chip were likely bonding wire failures. Voltage stress failures are not likely to self repair. I would agree, the fix is likely temporary. Many early chips used gold wire for bonding but later chips used aluminum. Which is better is always a question. The pads on the die were usually aluminum, while the package was often gold. These are acoustically bonded. One wonders if one put a capacitor on the lead with a non-lethal voltage and used such a heating method, it might be able to arc weld the wire back on. Using the method of heating might enhance the success as well. Dwight
________________________________ From: cctalk <cctalk-boun...@classiccmp.org> on behalf of Pete Rittwage via cctalk <cctalk@classiccmp.org> Sent: Wednesday, July 24, 2019 6:24 PM To: Jeffrey S. Worley <technoid6...@gmail.com>; General Discussion: On-Topic and Off-Topic Posts <cctalk@classiccmp.org> Subject: Re: Resurrecting integrated circuits by cooking them. On 2019-07-24 13:31, Jeffrey S. Worley via cctalk wrote: > Yesterday evening, in the process of refurbishing five very badly > treated Atari 800 computers I had a hunch and subjected a failed Pokey > chip (Atari Part CO12294 Wikki link https://en.wikipedia.org/wiki/POKEY > ) to high heat by way of the barrel of my soldering iron until > saliva evaporated from it in about 1 second. > > The chip, which did not work before in any of the machines now works > perfectly. > > Pokey (see wikki link) is common to all Atari 8-bit computers and > common in many Atari coinop video game systems. These chips are > becoming scarce, so much so there is a sort of replacement being > manufactured > https://hotrodarcade.com/products/pokeyone-atari-pokey-chip-replacement-for-atari-arcade-games > . > > The replacement Pokey only emulates the audio portion of the original > chip, leaving the PotKEY part unimplemented. Pokey gets its name from > Potentiometer Keyboard. It also handles the Atari SIO peripheral > signals, so without those an Atari computer cannot use standard > peripherals like serial disk drives, and other common interfaces. > Thus, for Atari computers a true Pokey is a must. > > I stumbled upon a fix for this one and wonder if I reinvented the wheel > or if this information may be of use to the group in treating other > sorts of chips. > > Reflowing is a treatment for a lot of hardware these days and generally > regarded as a hack which won't last. As modern hardware, CPU's and > video chips in particular run very hot, I can see how this might be, > but Pokey and most of the stuff we work with don't have this > environmental restriction. Most of our gear runs at 40 degrees > centigrade or lower. So I'm guessing the problem with my disused chip > was oxidation within the package and that cooking the chip a bit > cleaned things up? Any advise or observations would be appreciated. > > I tried this on another chip the same evening, an Antic. The Antic DID > work for a second or two, whereas it had before given no signs of life, > but then returned to its failed state. > > Best, > > Jeff > (Technoid Mutant) I tried this a year or two back with about 30 x SID, VIC, and PLA chips out of C64's. I heated them in the oven at about 250 for 15 minutes. None of them showed any more signs of life than before I tried it, unfortunately. -- -Pete Rittwage