The following is a detailed outline of exact procedures:
All required service performed in accordance with manufacturer with ORIGINAL components, NO cheap substitutes or re-stamps are ever used. Every switch and potentiometer, if equipped, is washed with Caig Deoxit, then rinsed a second time.
Alignment includes setting the indicator from bottom of scale to top end of scale to match fully closed and fully open tuning capacitor referenced to log. Entire path of tuning string oiled (pulleys, tuning knob shaft, tuning capacitor shaft, and friction areas of indicator). AM alignment includes peaking of RF and IF stages, trimming the tuning capacitor for equal sensitivity across dial, and confirming that the dial indicator is exactly linear with the tuned station i.e. 720kHz on dial is in fact 720kHz. FM section includes all of the same procedures including indicator alignment is also linear i.e., 98.7mHz is in fact 98.7mHz in addition to multiplex alignment for proper stereo separation and rejection of carrier.
Final confirmation of performance using RF and MPX generator. Preamp section tested for every single function and adjustment. All inputs, including phono confirmed as operating as designed. Phono section is also verified as having correct RIAA equalisation curve.
On solid state receivers like the Pioneer SX-1080 above, amplifier section DC offset, if adjustable, is set to exactly 0mV, and allowed to idle for 45 minutes to confirm stability. If non-adjustable and there is more than several mV of offset, we will match the differential pair to achieve this. Afterwards, the amplifier section is CORRECTLY biased to eliminate all crossover notch at the transition between device polarities (push half of signal switching to pull half of signal). This is done into a 4 ohm load at 10kHz with one watt of output. This impedance resolves, visually on the oscilloscope, any crossover notch, regardless of the impedance connected in normal use. The frequency of 10kHz is also used being as harshness from under biased output stages almost always manifests in the 10th octave of human hearing 10kHz~20kHz. It is set to the point where the output is free of crossover notch, and locked in. Just enough forward bias for a clean output, and a cool running output stage. This all applies to direct coupled output stages. In older capacitor coupling output designs, the AC balance of the output stage is set using the permanent user impedance (usually 8 ohms) for symmetrical full power clipping, performed at 400Hz and again at 1kHz, which is extremely important. This allows both halves of the signal to clip at the same point during full power transients. Bias is set in a traditional fashion as outlined above for direct coupled output stages. After confirmation of all functions and designed output power, the unit receives a complete external cleaning and detail removing all foreign substances.