When you press the Green button 110 volts are applied to the 1220 power supply. This by pases the K1 relay. When the power supply comes up the out put of the 5 volts latches the K1 relay so that 110 power can continue to power the power supply.
Measure the 5 volt terminal while someelse presses and hold down the Green Button. If you still get no 5 volts then replace the 1220 power supply.
Neal |