Picked this up at a garage sale. An old Japanese outlet strip, 2 pin, using an old fashioned Edison base fuse (the kind you should not put a penny behind of). It's a "Fedtro" model CON-6 Electric outlet control center. Made in Japan. Remove the fuse, and replace it with a light bulb, and now you have a dim bulb tester to test a radio under repair. Use a bulb of wattage of twice the radio's power consumption rating, and if the bulb lights brightly, you have a problem like a short in the radio's power supply (shorted filter cap or such that could ruin a power transformer). I suppose people back in the fuse days could have used a light bulb in place of a blown fuse to tell if they found the fault that blew the fuse. If the bulb stays lit, you haven't found it yet.