Pink Triangle Turntable Repairs
This was in need of some tlc, the motor supply used a DIN plug which had been connected to an Audio Vois power amplifier!
- 1) The power amp provides two 30V supplies at the DIN socket
- 2) The turntable needs around 9V to power the motor
This may have been a disaster in the making, however it turned out not too bad. The rectifiers had all but melted in the power amp and the plug had been wired to short the two, 30V supplies out, good for the turntable (saved the circuit from damage) not so for the power amp which needed the rather melted rectifiers replacing. The LF351 opamp also needed replacing as the speed was unstable.
The platter would stick if left for a day or two, or should I say the motor would. It was also very noisy if run without the platter\belt attached. Surmised the lower bearing\bush was worn causing the shaft to be pulled off center and lose the feedback pulses (the speed would increase), decided to turn the motor round 180 degrees, which made it work ok but this is only a temporary fix as it would need replacing at some point.
The chassis of pinky needed repairs where the motor fastened and the speed switch soaking in WD40, connecting a supply to the turntable got the motor working but any change in the voltage would alter the speed dramatically and it would have to be reset with the presets. I used a 9V regulated PSU which didn't allow the 45rpm speed to be set but we weren't bothered about singles.