Series of notes on weighing machine (6)
I believe the answer is:
scales
This clue is a double definition.
'series of notes' is the first definition.
(musical scales)
'weighing machine' is the second definition.
(I've seen this before)
'on' is the link.
(Other definitions for scales that I've seen before include "Graduated sequence of musical notes" , "Weighing devices or fish flakes" , "Sequences of musical notes" , "They're found on fish" , "Fish flakes or measuring devices" .)