Thorens TD 318 Auto Stop

[JoeTTD]

I have a Thorens TD 318 that won't behave properly on auto lift / auto stop at the end of the record. After much fiddlin' and cussin' I finally managed to get it to work properly but only at 45 RPM speed. It just won't work when playing a record at 33 RPM. My understanding is the function is dependent on both position of the stylus/arm AND the speed of the tracking arm across the record (with movement faster when the needle is in the runout grooves). I have adjusted the shutter and it does stop properly and in the right spot when playing a record using the 45 RPM speed. But not at 33. I am stumped as to how to fix this so it works properly at both speeds. Anyone have experience fixing this?

 

[number13]

I have worked on similar tables and have fixed that problem before. Let me begin by saying I know next to nothing about electronics, but have discovered
that velocity sensing circuits like your table has always seem to have a transistor associated with the circuit. That transistor usually has a trimpot mounted to the board
nearby. I fixed this problem on several occasions by measuring the trimpot value and de-oxidizing the pot. I then reset it to the measured value. This allows the
associated transistor to fire properly and the mechanism works again.

 

[JoeTTD]

Thanks for your reply number 13. I am not sure there is a trim pot on the board as it is upside down (when viewing it with the bottom cover removed) so I can't see what is on that board and I am not sure how to get at it. Your solution sounds reasonable but this may be a job beyond my shade tree mechanic skills.

 

[Brice]

Awaking this thread, I have exactly the same problem on my 318.
Did you fix it finally?
Thanks.