My dual power worked flawlessly for the first couple of weeks I've had it, but now it won't erase or program SST 27SF512 chips - even brand new chips, or ones that I programmed with it last week.
The harware checks out with one exception; Pin 1 = Vpp (12.55v), Vcc= 4.98v and the rest are 4.33v.
BUT, Pin 26 is 2.85v.
Is that normal?
It reads and writes 29c256 chips perfectly. I wish I knew what was going on here.