BennVenn wrote:
A couple of suggestions.
When reading back on your programmer make sure vcc and vpp are at 5v not the higer programming voltage of 6v etc... vpp should be at 5v or gnd.
I do not know how to change that. I just click read. Unless this is somehow done in the software, I am still novice to the ins and outs. The programmer itself is fully encased the only thing I can do on actual unit is plug usb in and power.
BennVenn wrote:
Write the rom twice with no erase between the two writes.
How is this possible? If the chip is not blank it will fail the write. Therefore soon as I go to write again it will just error on me.
BennVenn wrote:
An eprom is more or less a lot of tiny solar pannels tied to capacitors to hold a charge. They are charged when exposed to UV (set to logical 1). Writing a byte replaces the negative charge in a memory cell placed there by the solar panel with the VPP voltage. (This is not 100% accurate but good enough explanation to the non technical tinkerer)
If the memory cell was not erased enough its charge may not be sufficient to trigger a 1 or 0 condition when read at a high speed. This is likely what is happening. A long erase followed by two writes without an erase will make for a better read. If you can increase the write pulse time in your programmer this well help too.
These chips are suppose to be new, they are not suppose to have ever been programmed and they will read blank. They look new as well. Unless they know a way of removing chips w/out bending the pins at all and they know a way of getting every spec of solder off because these chips have none. I do not see how this can be the problem.