Advent 300 Tuning Dial Issue

[cepeter]

I'm hoping that someone with knowledge of the inner workings of the Advent 300's geared tuning dial can help me out. I recently purchased one of these amps sight unseen from someone who just had it completely restored as follows:

-- all transistors, caps, bias diode replaced
-- no-hiss mod trimmers, offset trimmers, FM compensation cap installed
-- DC offset and bias voltage set
-- FM tuner aligned
-- and all pots and switches cleaned with Deoxit.

After receiving it (by mail) and hooking it up I discovered that the tuner dial isn't working properly. The inner black knob spins freely, but doesn't rotate the outer silver bezel in tandem. The silver bezel should turn more slowly, something like one-half degree for every full degree of the knob, but it's not moving at all. On the other hand, if I twist the bezel portion the black knob turns, but this is inconvenient and not how it's supposed to work. Phono and AUX sections work and sound great.

The person I purchased the amp from didn't notice this issue beforehand, having not used the tuner at all after having it restored just a few weeks ago. Apparently, he only briefly listed to CDs through it before selling.

Ideas?

Best,
Christian

 

[cepeter]

Solved! Dave at davidreaton.com suggested that: (1) the outer silver ring might be bound and could be carefully pried out; (2) the ball bearings of the vernier mechanism might need lubrication; and/or (3) the tuner shaft might be bent and in need of straightening.

The silver ring was indeed bound, but the primary culprit was a bent shaft. I suspect the unit may have been unceremoniously dropped by FedEx somewhere en route to me. I very carefully straightened it as best I could with a pair of needle-nose pliers. The result isn't perfect, but it's about as close as I have any right to expect in receiver of this age. Once straightened, I was able to refit the outer ring of the dial so that it floats properly above the face and also free of the inner knob. I may need to periodically reposition the knob and ring as they shift some with use, but I can live with that.