[mole42uk]

I'd agree except that it survived the 260V - the ⅛W resistor usually drops half that but the shorted zener that drops the other half didn't give it an easy time. I think the PCB layout engineer knew it might be a little critical since the SMD resistor has about 5mm all the way around it on an otherwise pretty densely populated board.

Pondering on some of the design issues in this equipment, one of the things that seems to be evident is that small resistors are used in the supply rail as resistor/fuses so that if a failure occurs that might damage the supply or other parts the resistor becomes sacrificial. There have been two or three that I've found o/c with a down-stream transistor that has shorted c-e to potentially draw a higher current.