Before fault rectification and refurbishment: right channel defunct, crackling on left channel, two main smoothing capacitors leaking and there are numerous faulty & out of tolerance components. Rs, Cs, and semiconductors.
New Nichicon 100V 105oC smoothing and output capacitors are fitted in place of the old style bracket mounting types.
On older 303s with the crude diode bias arrangement we can fit a tiny BIAS modification board. This provides a more precise adjustment of the output transistor bias. Incidentally on all Quad 303 repairs we carefully set the bias to the sweet spot for minimum harmonic distortion. Too much and THD increases, to little, ditto.
We mount the Nichicon capacitors using our specially designed capacitor PCB. This correctly mounts the modern capacitors in place. It also conveniently allows the inclusion of L & R +rail fuses. In the event of a blown output device, etc., a fuse blows rather than a vaporised PCB track. In this example we replaced a failing bridge rectifier.
Some 3O3s we receive for service are in a very poor state. e.g., rusty case, bottom plate and front panel. We can restore the overall look, for an additional cost, by stripping and re-spraying these parts with primer and top coat. The re-sprayed sections (cover and bottom panel) will be in two tone colours similar to the original but not perfectly colour matched.