A WDB FLC OVERSHOT THE ASSIGNED ALT DURING THE DSCNT BY 700 FT BEFORE CORRECTING. THE CAPT (PF) HAD INADVERTENTLY DISARMED THE ALT CAPTURE DURING SOME CONFUSION OVER THE ASSIGNED STAR AND VECTOR INTERFACE THAT PRECEDED THE ALTDEV.

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WE WERE FILED FOR THE DANDD 1 ARR INTO DENVER AND AT APPROX 200 MI OUT WE WERE TOLD TO FLY A HDG OF 220 DEGS FOR THE SAYGE 1 ARR. AGAIN; AT APPROX 100 MI OUT; WE WERE GIVEN A HDG OF 230 DEGS FOR DUNNY INTXN; AND AT 75 MI OUT WE REALIZED THAT ON THAT HDG WE WOULD NEVER GET TO DUNNY. WE QUESTIONED ATC AND WERE THEN TOLD TO INTERCEPT THE 122 DEG RADIAL OFF DVV AND SLOW TO 250 KIAS; ON THE DANDD 1 ARR AGAIN. WHILE I WAS GETTING THE DANDD 1 ARR OUT (AGAIN); I SENSED THE PWR COMING BACK AND ASSUMED WE WERE SLOWING TO THE 250 KIAS ASSIGNED; BUT WHEN I LOOKED UP; I NOTICED THAT WE HAD DSNDED TO FL185 AND WERE STILL DSNDING. OUR ASSIGNED ALT WAS FL190. I TOLD THE CAPT OUR ALT SHOULD BE FL190 AND TO CLB BACK; BUT HE WAS UNSURE OF THE CLRNC AND CONTINUED THE DSCNT UNTIL FL183 WHEN; AT THAT TIME; HE CLBED BACK TO FL190. I BELIEVE THE CAUSE OF THE PROB WAS THE CAPT'S LACK OF UNDERSTANDING OF THE CLRNC AND TRYING TO DO TOO MANY THINGS ALL AT ONCE. SUPPLEMENTAL INFO FROM ACN 334553: GIVEN A HDG TO INTERCEPT A DIFFERENT STAR THAN ONE IN THE CLRNC. ABOUT 10 MINS LATER; I REALIZED THE HDG WOULD NOT WORK. I ASKED THE COPLT TO CHK WITH ATC ABOUT THIS HDG; BUT SHE CONVINCED ME IT WAS NORMAL. WITH ALL THE CONFUSION AT THIS TIME I UNARMED (WITHOUT MY KNOWLEDGE) THE ALT ARM WINDOW AND DSNDED TO FL183 BEFORE REALIZING WHAT MY ALT WAS. I CLBED BACK TO FL190. CTR DID NOT COMMENT. THE LESSON I LEARNED WAS TO INSIST ON CHKING WITH THE CTLING AGENCY WHEN I HAVE ANY DOUBTS IN THE FUTURE. ALSO; I NEED TO SLOW DOWN ON A NEW ACFT TYPE (3 MONTHS ON TYPE) SO AS NOT TO ERR IN FLT GUIDANCE SETUPS.