Free cams no sine up
Entire unit is detailed to look as close to new as practical. We connect the outputs individually to a dummy load that can vary from 0-32 ohms. To the inputs we connect a sine-wave generator producing a 1 k Hz tone with .775 volts output*.We bring the amplifier slowly up to clip or to its power rails noting that it hits both rails simultaneously.Cheaper as it may be, its a terrible design that will inevitably fail after just a few uses.The same goes for abandoning the use of quality control pots that use a nut to secure it to the chassis / face-plate.
In addition if you can see that much dirt on the surface, inevitably it has gotten in places where it cant be cleaned and may cause future problems.
We next check and / or replace any burned or intermittent panel / pilot / meter / indicator lamps.
Next any internal memory back-up batteries / capacitors are checked or replaced.
After establishing a basic 'state of health', we found that while both were running 'hot', one was running 'scalding' hot ().
They both did work, and the tuners and all basic functions were there, and they each didn't sound necessarily offensive, but upon further testing into a dummy load and on a scope, we found bias issues.