here is the way to test what is wrong :
- connect a chip from RS to a breadboard with the usual setup (no battery) and just gnd,vcc, scl , sda, and low freq. xtal and possible pull up. then run the scan test. it should return 1 address
- connect a desoldered chip to the breadboard(swap it for the one from RS). it should give the same result.
- if both work and they should, there is a problem with your board.
is there a circuit? for which purpose were they made?
you might want to swap the xtal for a new/different one. (dont know if the chip should respond with/without) xtal.
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