After putting in a truckload of electrolytics to get rid of ripple in the r ace I have some residual noise in X 10 mode. I am wondering if it might be almost normal.
In normal the trace is nice and sharp, but in X 10 it is about 0.8 mm. high .
Before the caps it had something akin to a sine wave at double the power su pply chopping frequency in all modes, unaffected by the setting of the V/di v. It would only go away in add, invert B.
With the case off it does pick up some additional noise, which is gone when you set it to maximum gain, which is when the attenuator is just a piece o ff wire, and ground reference on the input. At that point you are getting a pretty true picture of how much noise is actually in the system.
I have been tripped up by expecting too much. For example working on an old FM which works but I think no way it is working right because it doesn't g et the Akron stations (from Cleveland). I wonder if this is what's going on here.