Acoustic Research Amplifier Repairs

Acoustic Research A-05 Stereo Integrated Amplifier

Acoustic Research A-05 Stereo Integrated Amplifier Acoustic Research A-05 Stereo Integrated Amplifier

This didn't want to play, was full of dust, didn't look anything like it does in the pictures one of the UPC1225H front end ICs was faulty, sounded fine after replacment.

Acoustic Research X-10 Stereo Receiver

This didn't receive FM radio. I found the tuning voltage (which is supplied from the small transformer) was dropping on switch on, due probably to the other parts of the circuit taking current. The smoothing capacitor for this was only a 100µF, so fitted a 470µF and it managed to keep the voltage high enough to power on okay. This feeds a voltage regulator to the varicap diodes.