First time poster so I’ll start with a hello and some quick background.
I’ve only recently been bitten by the vinyl/vintage audio bug thanks to a neighbour and have been having a great time over the past few months bringing a Dual 1209 back from the dead and getting a little Sansui AU-101 sounding sweet through a set of B&W DM110’s. This has given me hours of joy and all for the grand total of around $150 (Aussie that is) to date.
Now onto my issue/question, I’ve just acquired a mint condition Pioneer PL-71 which has a serious over speed problem. When set to 33 I’d estimate it spinning close to 45 and when set to 45 it’s spinning faster again!
I’ve done a heap of googling and reading and know that the PL-71 have speed stability issues typically related to switches, trim pots and PSU caps so the below is what I have done to fault find to date.
1. Bypassed the 2 x power switches (yes mine is the three switch version) and speed select switch to eliminate these as a source.
2. Measured the 1kohm trim pots (both ok) and also interchanged them to eliminate as a source.
3. Measured the PSU output at 19.5 DC stable and with surprisingly very little noise given the original caps are still place.
4. Used a DC bench power supply (using a range of voltages) as an alternative to the internal PSU to be sure it wasn’t the issue.
All this kind of leaves me with just the motor, both the external and on board trims alter the speed it’s just that overall its spinning way to fast.
I’m wondering if anyone has seen this before, has any ideas or possibly has a schematic diagram for the motor control board (FL-EGP018).
Any help would be greatly appreciated as I’m desperate to get this, in my humble opinion beautiful table back up and singing.