pylon:
Does your old read also read the blue key chain tags that came with the new ones? If not, the new readers might not be compatible with the MIFARE standard...
That risk is always there if you buy cheap stuff on ebay without any documentation.
Yes my old reader reads both the keychain and the regular industrial tags. As you mentioned I think the problem is the new readers use a limited performance clone of the original NXP chip ...there is nothing that is printed on the SoC. As time passes you realize that E-Bay is a good starting point for makers but not for serious industrial solutions.
Just wanted to know if there is anything that can be done to tweak the readers by changing any setting values on the MFRC522 library ? ( The new readers do pass the init phase and report Software Version 2.0 )