[jjl]

These are classic symptoms of a switch mode power supply that is not "switching". Assuming you have around a 110V mains supply in your location, the large caps that are charged to 162V will be on the primary side of the supply and are supplied with full wave rectified mains.

Often in supplies such as these, there is a high value resistor on the primary side that provides a "startup" supply to the switching circuitry. Such resistors which are often around 120K in value have the habit of going open circuit thus disabling the switching circuitry. I'd (safely) discharge the large capacitors then have a look for such a resistor and measure its value.

It would be a good idea to obtain the service manual for your signal generator.

Please be careful - mains powered equipment and switch mode supplies contain hazardous voltages.

John