[Techtoolslist] EPROM Programming Woes...

[Jess Askey]

Heya Folks...

I have had a need to program a bunch of EPROMs lately (27128 varieties) and Im not sure if there are sunspots or something, but I can't seem to program anything on either my 29B OR my Intronics USB Programmer... I have successfully programmed like 4 EPROMs out of like 40 attempts. My EPROM's are old pulls from either Atari boards or other used ones I have acquired over the years in storage sticks.

They are either

ST 27128A
Fujitsu 27128
SEEQ 27128
TI TMS27C128

Im being fairly careful about the programming voltages and the 29B identifies the IC before programming it.

On the 29B I just get an Error #22 Programming Error right away.

Sorta the same thing on my Intronics.... Set it up, verify blank, program, error right away.

Are these just too old? Anyone have any good tricks?  The strange part is that I was having this exact same issue last night, then all of a sudden my 29B programmed 3 in a row just fine... today, nothing.

Thanks
Jess