Time-delay thermal photocell shutting off in the DARK?

[GEsoftwhite100watts]

Yep...is this an actual failure mode?

Have a circa '93 Fisher-Pierce photocell that is doing this; it turns the light off after the 2 minutes (light was on a switch), even in the dark!  It used to be a very insensitive PC so I highly, highly, highly doubt it was "seeing its own light", plus it didn't seem to cycle on and off. 

I tried a new bulb, so I know it wasn't a cycling bulb either...

Thoughts? 

[Mike]

I had a Fisher Pierce so this too and knew of a light near me that did that. Don't know how to fix it. It's just junk now unfortunately. You could rip the guts out and connect the two smaller prongs together to make a shorting cap.

[lightingfan8902]

Could be a defected circuit board, or the photoeye (photoresistor) isn't the right resistance value for use, is my guess.