Marantz TT2400 Direct Drive turntable
One of the more interesting jobs of late, as it required a custom solution, and some reverse engineering of the auto return and pitch control circuit.
These are the challenges I enjoy - no schematics for this model. With a thorough understanding of turntable power circuits and a background working with sensors, I was able to work through these circuit faults. Worth it for an uncommon turntable of this vintage.
The reed switch actioning the auto return was in working order - fortunate, as its not a common form factor, not being in the usual place you find them inside turntables. Note the uncommon array of motor and gear for auto return movement of tone arm.
With either an open or closed circuit actioned by the reed switch, I was able to work back through the circuit and replace a couple of components that had lost tolerance.
Pitch control was a similar process, after ruling out the the two potentiometers. The unsteady 33 speed was corrected after replacing some minor components. An elementary process of fault finding a pitch circuit issue without a schematic, for any technician.
Whilst less technical, the more interesting part of the job was having the "Z" shaped tone arm lifter part 3D printed. Owner almost did not want to go ahead, citing a new turntable from JB HiFi was almost the same cost (!) but realised the error in his perception of what you could buy from JB for @$350 was far inferior to this classic style, direct drive unit from the early 1980's. Performance, design, tone arm and plinth quality - most vintage style turntables with solid plinths are never comparable to new <$500 turntables of this day and age.
3D printed piece arrived in a timely manner, fit (with some slight adjustments) calibrated and returned to customer - ready for another 10 years at least before preventative maintenance.
If you are reading this, and do require the replacement part for tone arm lift, I have spares on hand for $40 each, and can give advise on fit and calibration only - I cannot walk you through the disassembly and assembly. If you have never taken a turntable and tone arm apart, I would strongly suggest taking to a technician to perform that.