I've been working on re-modifying a Trio turntable that Nickthedentist passed on to me a while back. A simple modification:
I soldered 2×33k resistors in parallel to give 16.5k; connecting this combination in series with the servo feedback loop results in the speed being bang on. This was done initially by connecting a ten-turn 20k pot and adjusting it to get a zero-beat when using a 1kHz test tone record track against my smartphone tone generator app set to 1kHz. I disconnected then measured the pot with my Fluke DMM hence the 16.5k value.
The cartridge/stylus combination works perfectly - I set the tracking at 3 grams & tried some of my grandparents' records earlier. At this point - captainpugwash: take a bow, mate
Although very crackly/scratchy, Enrico Caruso singing 'O Sole Mio' is really rather good (especially for a recording that's around 100 years old) - and for me, that's saying something as I've never really been very keen on operatic stuff!
Guy