Got my TB6600 drivers from eBay. They were same as described here BL-TB6600-V1.2 D412.
Heatsink with no thermal compound. Added thermal compound and changed R11 from 15k to 33k.
So now I am on safe Vref. Max Vref value now is 1,87v. So I can get about 3A current.
Tested all 3 drivers they seem to work well.