***** The Following Information Is For Reference Use Only*****
*****For Approved Data Please Refer to The Associated Installation Manual; Pilot Guide or Flight Manual Supplement*****
On the Synchro Valid input R1 and R2 must be installed or the EX500/600 will sustain damage.
If the unit is receiving HDG data, but the HDG is jumping all over the place check:
400Hz output of the A/C supply
Check reference Hi and Low compared to X,Y,Z inputs. The reference and signal input wave-forms must be identical.