This is pretty typical of what I discover. This is a major brand name device and it makes me wonder how it is possible for a system to exist when no one knows what is going on anymore. Devices with back doors with passwords like 12345670 and choices made without any understanding of consequences. This circuit was obviously done by hand, but the hand has no idea what the goal is and cannot make intelligent choices. I am pretty sure that is not a diode at D9 and that is a missing bias resistor on Q2 as well as individual parts that have improper silk screen.
It is only slightly consequential in this case, but there are many places where decisions have been made that leave holes that ask to be filled with random desire. There are places where this same thing is being done where the consequence is genetic stability. The big picture becomes more clear with each discovery and I suspect that greed and incompetence have collaborated again.
I suspect that the solution to complexity has become failure. If the human race suffered CCD (Colony Collapse Disorder), who would diagnose it?
I am considering making a device that looks at the matrix of connectivity using high frequency radio waves or NMR and a detector with high Q to look at circuits in the electrical dimension as well as visually. It is possible to perform ATE ("using" Automatic Testing Equipment) while the circuit is operational and I have done it many times. It is obvious in use as well as observation that this circuit fails and why it fails. It is easier for me to make something that works than to depend on being able to buy something that is completely functional. I think I will just design a circuit that looks at itself first and then cannibalizes other failed circuits. Ah, the evolution of replicators, survival of the fittest circuit, and selection by effectiveness. It may be so that AI will be the only possible way out of this and perhaps it will fix the human circuit and replace the missing parts that have been left out of the design. Be kind to your design so that it may be kind to you.