Been agonising over that bloody DC socket connection, the 47 ohm resistor (470J) and series 1N4007 diode connection etc.
The Amptweaker manual clearly states that the four control illuminating leds only light up when using an external DC power supply NOT when using a battery. Took me a wee while trying to figure out how this is done and the solution is elegantly simple
. Here is how this is achieved
The cathode of the last led in the series chain connects to the +9v battery terminal - it is also connected to the switch contact terminal (where the +9v battery lead is normally connected) AND the centre pin terminal of the DC socket
ALSO connected to these two terminals is the cathode of the 1N4007 diode (the anode of this diode is then connected to the 47 ohm 1W resistor and this is then connected to the ring terminal of the input jack socket ).
The remaining DC socket terminal is then connected to the + 9V power rail main filter capacitor, op amp #8 pins and anode of the first led in the series chain, etc.