Repairing a Sharp Optonica RP-117H
This turntable was bought on Ebay “for repair”. The first problem was that the turntable tray was loose and wouldn’t retract or come out. On removing the covers, a shield over the tray motor and the motor itself it was obvious what the problem was:
Broken tray gear wheel
The gear wheel is split, and has dropped off the motor drive. Here is a close-up of the gear:
Closeup of gear
Because the gear had shrunk a little (probably why it cracked), simply epoxying it together at the crack didn’t work: this made the hole too small and prevented the gear from going back on to the drive shaft. I carefully bored the hole out a tiny amount, then used epoxy to glue the crack and the gear back onto the shaft: I clamped it there for 24 hours.
Next problem was a broken belt for the platter itself: to reveal this involves removing a plate underneath the turntable tray:
Broken belt on motor
The belt had disintegrated, leaving a rubbery mess over the turntable and the motor capstan – removed fairly easily with rubbing alcohol. I ordered a replacement belt, and fitted it by feeding it through from the top of the turntable. It was a bit fiddly, but I’d read somewhere it was a nightmare – I didn’t find that.
Now the turntable tray moved in and out, and the turntable turned. The next problem was that the stylus trays were not moving. These trays move linearly across the deck. There is a clever mechanism with worm gears and a slotted metal disk and opto-transistors that move and detect where each stylus arm is. Here is the mechanism:
Stylus trays mechanism
Just visible at the back of the mechanism is a rubber belt – of course this turned out to be worn and was slipping on the motor and not moving the mechanism. I replaced it with a rubber belt I happened to have in my parts box and fit very nicely. Now the whole mechanism worked. Here is a video of it in operation, showing the switchover to Side B from Side A, which involves the turntable motor reversing direction.
The fitted stylii are by AudioTechnica. The Sharp part number is STY133.
AudioTechnica Stylus
Although the turntable now works, it initially played several LPs without issue, it has now developed a random periodic click/thump, almost as if the record is scratched. This is a little peculiar and hard to understand. To be continued ….
Sharp Optonica RP-117H and Sony CDP-X555ES
