...i replaced the power supply in my fons with a separate battery eliminator producing 9v dc. its working splendidly, but is this the wrong voltage?
Welcome... You have a great turntable! And if the 9V
DC supply is working splendidly, then it's absolutely the correct voltage! :thmbsp: :beer:
I have no idea what type of power unit you are using, but if it's an external regulated/stabilised 9V
DC supply, there may even be sonic improvements over the original unregulated (internal)
DC supply.
In fact, there is evidence on the later Fons International circuit boards that they intended to regulate the
DC voltage with a 9V1 Zener diode.
Unfortunately, there is no provision for a current-limiting resistor which means that the Zener diode would have been destroyed within milliseconds of power-on.
Or perhaps the regulated 9V
DC idea was abandoned because the turntable may not have reached its designated upper rotational speed.
...if i could run the circuit on 12v dc then a car battery could be used, which would be ideal for me.
A fully-charged 12V car battery normally supplies >14V at the terminals. Whilst it'll work, it may also stress the motor driver transistor VT4, which cannot dissipate much power.
...i have just relubricated the main bearing and am loving it
I use
CV Lith-Moly Grease for silent operation. :nerd:
...ps the mains switch made a loud pop through the speakers when i first got the fons, hence the replacement power supply (which is always left on).
That suggests one or both suppression capacitors across the terminals on SW0 (the ON/OFF mains switch) have failed.
If you have pictures of your modifications, please post them here.