Some products have dozens of internal connections for transformers, B+ rails, driver to power transition, etc.
Every connection, unless soldered or compression fused, acts as a variable resistor.
As these connections change temperature, they change value and alter the level and phase of AC signals.
As the connections age, the deltas become more extreme due to corrosion from metal or atmospheric interactions.
!!!! WARNING - Only for the technically skilled !!!!
Over the years, I have made permanent improvements to electronics by removing all unsoldered internal connections.
Every connection, unless soldered or compression fused, acts as a variable resistor.
As these connections change temperature, they change value and alter the level and phase of AC signals.
As the connections age, the deltas become more extreme due to corrosion from metal or atmospheric interactions.
!!!! WARNING - Only for the technically skilled !!!!
Over the years, I have made permanent improvements to electronics by removing all unsoldered internal connections.