Winbond W27C512 EEPROM erasing/writing
According to the W27C512 datasheet it needs 13.75~14.25V. This tight voltage range is specified to ensure that all chips will erase properly despite process variations. A lower voltage is unlikely to damage the EPROM. It will probably still erase properly down to some lower voltage, but the actual limit is not known and will vary between individual chips. 

I tried using 12V and it appeared to erase my W27C512 successfully. However I only verified it at 5V so it is possible some cells didn't erase fully (the datasheet suggests verifying at 3.75V to "ensure a substantial erase margin"). If your chip erases at 12V and verifies at 3.75V then it should be OK for experimenting. Just be aware that programmed data might become corrupted, and don't use it in a critical application.