If you have 15.6V across R3, then you have wired it wrong or your regulator is blown, there should be only 1.25V across R3....HI Sir, I have checked the voltage around R1, R2, and R3. R1=9.92V , R2 = 12.03V and R3 = 15.68V.
R1, R2, and R3 are the one connection between the ceramic cap and electrolytic cap with LM388.