When I had access to a wire bonder, we took EPROMs that had been plugged in upside down and removed the lids. We'd see a blown wire and replace it.
On several of these parts we found that 100% worked. So it would seem that no silicon damage was done, just the bonding wire was blown like a fuse. I doubt this method would repair those blown from excess programming voltage. Dwight ________________________________ From: cctalk <cctalk-boun...@classiccmp.org> on behalf of Curious Marc via cctalk <cctalk@classiccmp.org> Sent: Friday, December 22, 2017 9:04:07 PM To: Mark G Thomas; General Discussion: On-Topic and Off-Topic Posts Subject: Re: EPROM baking I see the same things. Some chips just won't reprogram. Symptoms include failure to program just like you, but also "chip backwards" errors. Can't remember the chip brands, I just toss them out when that happens. I have not found any way to resuscitate them. Maybe ~10% of the chips I tried had this, so rather frequent, but never any from new old stock. The failed ones were all previously programmed chips, just erased. Marc On Dec 20, 2017, at 6:18 PM, Mark G Thomas via cctalk <cctalk@classiccmp.org> wrote: My stash of TI and NEC 2732s seem to have the disease, but my ST, Mitsubishi, and several others program fine. In the case of a bunch of 2732s, I have tried both a vintage DataI/O 29A programmer and a modern Batronix programmer, with the same results. I don't think I have a programmer problem. I still swear someone in the late 80's had me baking EPROMs in an oven to restore their programability, but I don't remember the specifics. I tried a few at 450F for 15 minutes, but they still won't program. Mark -- Mark G. Thomas (m...@misty.com), KC3DRE
