Ok here is the start of it.
Flip the amp upside down and take the cover off.
Here is the inside.
Most amps will have somewhat the same setup, the donut looking thing is the transformer so you know that area is the powersupply section.
There they make DC into AC pass it over the transformer stepping it up to a higher AC then converting it back into DC to supply 24-105volts
for the AMP section.
CH1 and CH2 would be LEFT and RIGHT, they r 2 seprate circuits. So if you had just the left cutting in and out you would start tapping in either CH1 or CH2
to see which is more sensitive to the tapping.
The input section and signal preamp section. If your loosing sound on both channels at the same time this would be a good area to start.
As you start getting closer to the component that is loose, it will start acting up more with the tapping. Start lightly prying on components.
After you think your in the general area of the problem, it's now time to disconnect everything and strip the rest down to gain access to the back side of the circuit board.
Will be back with more.
