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Friday 3 November 2017 at 12:34
Hi,
The problem is not the programmer but the EPROM chip itself. May be too old.
Erasing the EPROM set all bit to 1 (ie, all bytes should be FF) and programming set only bits to 0.
Here, you try to program a 3A (00111010) value, but the verify (read) after programming return the value 7A (01111010)....
Source: http://pinside.com/pinball/forum/topic/tl866-cs-universal-programmer-unknown-error-programming-2716#post-4054799