I have an old Sony PS 300 turntable, 110V, and the motor got damaged due to connecting it directly to 220V electricity. Since then, I've bought more than 5 new motors, replaced the damaged one, and bought a new transformer to convert from 220 to 110, but still I am unable to reach the required speed. I get 40rpm instead of 45 and 29-30 instead of 35. Can anyone suggest a solutio?
Most countries with 110V power use a frequency of 60Hz and the majority of countries with 220V use 50Hz. This would explain the speed difference.
Those Sony turntables would have been produced for markets worldwide, so there should be motors available for 220V/50Hz. The easiest solution would be to find one.
Here's a related question from someone who has the opposite problem.