I've got a dual power and have read through the procedures for the sst 27sf512 chip but I'm still having problems. It seems that I can erase a new chip with nothing on it and can program a new chip successfully. For some reason, I can't erase a chip once it's been programmed the first time. I tested the VPP and got a value of 12.57v. Any hints on what could be wrong?
Yes, those jumper settings are what I have been using. I don't believe the willem dual power is up to the task of programming a 27sf512 reliably, it worked great on the at29c256 chips. Think it's time to ditch this burner and move on to something designed to do the job.
WOW! That would have been nice to know. Why in particular do you feel that it is not up to the job? I just bought another burner (Moates), but I was wondering why you felt it would not work well for this particular chip.