The datasheet told me there are two problems:
1: the write time is to short, only 1 ms instaed of 45 minimum. This could be overcome by writing several times?
2: vpp should be 25v not 21V. Therefore I'm planning on making an adapter so I can put 25v to the vpp pin.
For future reference:
My tests gave me this results: (using my cheap TL866CS)
1:writing several times?
There was no reliable result in writing several times, even when I programed the EPROM 50 times in a row some chips lost some BIT's the next day? Some kept working.
There where even chips I could not program at all, they keep throwing errors.
2: I used a machinepin socket and removed pin 21. I provided 25v from my PSU to the vpp pin of the chip while programming. All chips worked fine after one cycle, even the next day.
The chips that could not be programed in the first test, worded fine with the 25v vpp. (after erasing)
For now I did two cycles on the chips that I use in the pinball I made them for (Just in case) and they keep working for one week now, I think they will keep working for a long time. The one's I programed only ones also test fine till now.